QandA kitchen garden Booklet Summer 2011

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Questions Answers YOUR FRUIT AND VEGETABLE QUERIES ANSWERED

76

S EM L B PRO LVED SO

• Best veg for small plots?

• Reason tomatoes split?

E E

• Why onions flower?

FR

H N IT HE N

W C DE T R

KI A G


Solve your crop problems

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rowing your own fruit and vegetables is very rewarding, but sometimes it can be challenging when pests or inclement weather strike. In our exclusive Kitchen Garden supplement this month we offer some real solutions to 76 common problems that may be found in the fruit and vegetable garden. Judging by the KG postbag the most troublesome pest is slugs and we have some top tips on controlling this pest on page 5. Another common complaint is onion downy mildew which we cover on page 8. And if

you are fed up with small holes in your brassicas, it might be flea beetles... which we tell you all about on page 10. If your crops are suffering from a pest or disease attack then you might want to check out our table below which lists some of the current controls including organic options to help keep your plants healthy. Wishing you happy and healthy growing season

Products to control pest and diseases in the kitchen garden (The list is not exhaustive so do check the classified pages at the back of KG for more products and also your local garden centre and DIY store) PRODUCT

ACTIVE INGREDIENT

CONTROL

ORGANIC?

Plant Rescue Fruit and Vegetable (Westland Horticulture)

Lambda-cyhalothrin

Insects on a wide range of fruit and vegetables

NO

Organic Bug Free (Bayer)

Fatty acids

Many pests on fruit and vegetables

YES

Provado Ultimate Bug Killer Thiacloprid

Many fruit and vegetables (see pack)

NO

Savona Insecticidal soap

Fatty acids

Most fruit and vegetables

YES

Slug Death XL (Vitax)

Ferric phosphate

Slugs

YES

Nemasys Grow Your Own

Naturally occuring nematodes

A mix of nematodes that predate pests such as thrips, codling moth, caterpillars, YES – gooseberry sawfly, root flies, a biological control leatherjackets, sciarid

Plant Rescue Fungus Control (Westland)

Difenoconazole

Fungicide control on brassicas, apples, celery, cherries, plums and other crops

NO

Bordeaux Mixture (Vitax)

Copper

Fungicide to control disease on apple, blackcurrant, celery,cherry, gooseberry, peach, plum potato and tomato

NO

Control many fungal diseases on selected crops including apples, pears, potatoes and outdoor tomatoes

NO

PEST CONTROL

DISEASE CONTROL

Fruit and Vegetable Disease Copper oxychloride Control (Bayer)

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July 2011

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Potted coriander

Q

Can you grow coriander in a container. If so what size of container and when should I sow the seeds? It is possible to grow coriander in a pot but it is probably best to sow the seed direct in a large pot of compost – a pot at least 30cm (1ft) diameter or preferably bigger and filled with some John Innes compost either Nos. 1 or 2. This compost mix tends to hold onto moisture better, which is important with coriander. If the plant experiences drought conditions it may go to seed quickly which is not ideal if you want to harvest the foliage.

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Bolting spinach

Place the pot in a sunny position in the garden and sow about April to May when it is warmer. That said there is an variety called ‘Calypso’ that can be sown in a small pot or trough and when large enough just snip leaves off as and when you need and treat like a cut-and-come again salad crop.

Best veg for small plot

Q

I have started growing vegetables this year but only have a small garden. What crops should I sow to get the most produce from this small area? The obvious veg to include would be beans, especially French and runner beans. These don’t take up too much room if you grow the dwarf French beans in a short row. They are very productive and you can be picking for several weeks. A wigwam of runner beans will also produce good harvests. Courgettes are a must. They make quite big plants but just a couple of these will keep you in courgettes for weeks. Carrots are great because you can get a lot of roots from just a small row. Salad leaves, especially the mixed seed packets, are great for the summer. Different leaves can be plucked as and when you require them. Kale is a good crop for a small plot especially in winter. Leaves can be harvested when required and

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more will grow over several weeks. The crops which are not so good for small plots include parsnips that are in the ground for almost a year and take up a lot a room. Potatoes take up space but then again they could be grown in barrels or sacks. Peas are delicious but you need a lot of plants to produce a heavy crop. However, just a few plants will give you a taster. Cabbages and cauliflowers also take up a lot of room and so does broccoli, but at least this produces lots of spears for several weeks so is maybe worth a plant or two.

Q

Why does spinach always seem to produce flowers really quickly before I have even had chance to harvest much of it? Spinach is known as a long-day plant, which means that when the day length increases it initiates flower buds. Spinach sown in early spring will run to seed in summer. If you can give the plants plenty of water in the early stages of growth and enjoy the young leaves early then keep sowing more spinach every three weeks or so to keep a succession of young plants and leaves. If you sow after mid summer, the bolting is usually less of a problem. There are also some more boltresistant varieties such as ‘Monnopa’, ‘Spokane’ and ‘Palco’. Don’t give up just sow some more, you will get some baby leaves now for the late autumn.

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VEGETABLE QUERIES www.premierpolytunnels.co.uk

Hardening off

Q

What is meant by hardening off crops in spring? Hardening off plants is simply getting them used to colder temperatures. If you grow tender veg such as tomatoes and courgettes in a warm greenhouse and plant straight out on the veg plot in March or April, you run the risk of halting their growth at best or turning their leaves purple with the cold and killing them if a frost occurs. In April

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courgettes, tomatoes, French beans and other tender veg can be placed outside during the day and brought in at night. Alternatively place them in a cold frame as temperatures are likely to be cooler than a greenhouse but still protected from frost. At the end of May/beginning of June you could plant them out safely. If planted earlier they may be fine but watch out for any late frosts and be ready to cover them with some fleece on cold nights.

Slug control

Q A

How do I keep slugs from eating my crops. I have tried traps but they don’t really help and I don’t like to use pellets. What else can I do? Slugs are public enemy number one as far as gardeners are concerned and as we can’t totally eradicate them, we have to just learn to live with them to a certain extent, especially if we want to be organic. However, it would be worth trying a biological control which uses a natural predator of slugs, a nematode. It can be bought in a pack, mixed with water and applied to the soil. It is good because it is natural, you are just adding more numbers of the predator to the soil and it won’t harm plants, birds or other animals. The soil temperature does need to be at least 5C (40F) for the nematodes to work and the soil has to have a certain level of moisture for the nematodes to move around in. So the best time to apply is in spring and early summer.

Whitefly problem in greenhouse

Q A

How do you deal with an infestation of whitefly in the greenhouse? This is a really difficult pest to control once it has taken hold. From your correspondence you have done the right thing by clearing out the greenhouse and washing it down throughly but there is still a possibility of the pest surviving and gathering strength again in the spring. In this situation it is best to use biological control. This uses a natural predator such as Encarsia formosa or delphastus to control the whitefly. For these to work at their optimum the temperature needs to be at least 18C (64F). Also there needs to be some whitefly present to feed the predator and keep it ticking over. This should control the whitefly down to manageable levels. Biological controls can be bought by mail order. Try Defenders; tel: 01233 813121 www.defenders.co.uk or Green Gardener; tel: 01603 716986 www.greengardener.co.uk

Raised bed compost

Q A

What sort of compost should I use to fill some new raised beds?

It depends a bit on what size of raised beds you are building but even two or three would require a fair amount of soil. I would suggest you order some top soil or alternatively John Innes No. 3 compost. This could work out expensive so you could make a concoction yourself using a mix of your soil, garden compost or well rotted farmyard manure and some sharp horticultural sand. www.kitchengarden.co.uk

July 2011

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Aubergine pest

Q A

What could be causing the leaves of my aubergines to turn yellow? They are grown in a greenhouse. It could be a symptom of red spider mite attack. If they are quite speckly close up but giving an overall yellowing look from a distance then this pest could be the cause. If you look underneath the leaf check for tiny beige coloured insects and sometimes a fine webbing. Rub the leaf with your fingers and if a deposit comes away like a fine sand then this is almost certainly red spider mite. Aubergines are particularly vulnerable to this pest. It is a difficult pest to control once it takes hold. Keep the air in the greenhouse humid and mist the leaves with water. This pest hates high humidity. Also try a biological control. This does rely on there being some of the pest present, which you clearly have.

Rabbit menace

Q A

Have you got any tips on protecting my veg garden from maurauding rabbits? This is a really difficult one to solve. Ideally your plot should be surrounded by a wire fencing of a 2.5cm (1in) mesh. It needs to be about 90-120cm (34ft) high and about 30cm (12in) extra needs to be buried in an L shape below ground. It this isn’t possible then I’m afraid there is little you can do as rabbits are tenacious and will eat virtually anything. If you are finding certain crops are a problem grow these in the confines of a smaller section that is wired off or perhaps create some wire domes to place over individual rows of crops.

Controlling bindweed

Q A

How do I control bindweed. I have it growing on my new allotment. Any suggestions? Bindweed is a really troublesome weed that does spread well and is not easy to eradicate. The roots go down a long way and if you don’t get all the root out, it will just regrow. Perhaps the best product to use is glyphosate either as Bio Glyphosate or as Roundup. These products will travel through the plant’s leaves and down to kill the roots. The disadvantage is you need to make sure there is no drift onto crops especially tomatoes or potatoes which are particularly vulnerable. Spot treat the clumps of weed and reapply if it returns. With hand weeding and chemical controls, you will eventually weaken the weed. 6

July 2011

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ALLIUMS www.premierpolytunnels.co.uk

Alliums

Leek miner trouble

Q A

Rusty leeks

Q

I have grown leeks for the first time this year and they have developed orange blisterlike markings on the leaves. Is this rust disease? How do I cure it? Mild infections of this disease are common and do not usually do any harm. In fact as the season progresses sometimes the plants just grow through it and it ceases to be such a problem. However, in severe cases the leaves can be damaged to such an extent yields may be reduced. Leek rust is a fungal disease that is made worse by growing plants too close together, also excessive nitrogen in relation to potassium in the soil. It might help to apply a tomato feed which will harden up the leaves and make them more resistant to attack. There are no chemicals you can apply to prevent the spread but our growing for show writer, Medwyn Williams, has a useful tip. He puts a

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Seedling collapse

Q A

What could cause several pots of onion seedlings to just keel over? This is a classic case of damping off. This is the term used when seedlings (not just onions) suddenly collapse and die. The cause may be numerous but generally is from a fungal disease which can damage the base of the stem. If you look hard enough you might notice a brown rot at the base. The most common reason for damping off is over watering. If soil

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little Vaseline onto the infected areas to arrest the spread of spores.

is watered well at sowing it is not usually necessary to water for a week or so, and once the seedlings are through if the soil is dark and just moist then that is fine, leave well alone. Only water when the compost surface is clearly light in colour and dry. Keeping the dryness at the base of the seedlings will help keep damping off at bay. If damping off is a regular problem consider changing your compost, clean out your pots more thoroughly and only use tap water to water the seedlings, not water from a butt.

How do I control allium leaf miner which has destroyed my leeks? Allium leaf miner was first spotted in the UK in 2003 in the West Midlands. Napomyza gymnostoma was a problem in Eastern Europe initially but has now spread across Europe. The larvae feed on the stalks and bulbs of leeks and other alliums, tunneling between the layers of the leaf. There is the possibility your pest is the more common leek moth as the symptoms are very similar. If you can find one of the larvae look for a yellowish-green grub with brown head and you should see some legs if you look closely. The larvae of the allium leaf miner is creamy white with no brown head or legs and its pupa is brown as opposed to creamy coloured for the leek moth which causes similar problems. The adults lay their eggs in spring so it is best to cover crops from February with horticultural fleece. After April there is less danger so planting out pot grown leeks and onions after this period will help. DEFRA suggests suspected outbreaks should be reported to the Plant Health and Seeds Inspectorate. If you suspect you have allium leaf miner do let your local DEFRA office know or email planthealth.info@defra.gsi.gov.uk It is worth noting that if you spot what looks like allium leaf miner but it is a more yellow-green/brown coloured grub, then it is more likely to be the common leek moth. The same control methods apply. A full list of regional offices can be found on the DEFRA website or phone 01904 455174.

July 2011

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Onions bolted

Q

My crop of ‘Ailsa Craig’ onions has bolted before I had chance to lift. Will I still get a harvest from them and will they store? Onions do occasionally ‘bolt’, which is the technical term for early production of flowers and seed heads. Stress is usually the cause, although stress in plants can be due to numerous reasons including unusual weather patterns, drought, pest damage and also planting the bulbs early especially in a cold spring. It would be best to take the flower heads off and lift the bulbs as soon as possible, dry in the usual way by leaving on the soil surface for a couple of days in dry weather. It is best to eat the bolted onions as soon as possible as they don’t tend to store as well.

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Mouldy onions

Q

I have been growing onions on my allotment for 30 years but myself and other plot holders have been having trouble with downy mildew on onions. Can you tell us what I and other plot holders can do? This is a tough one to solve because this is a disease outbreak on an allotment site that has been worked for 30 years and it is inevitable that there will be a build up of disease in the soil, so trying to eradicate it will be almost impossible. Rotation of crops will be virtually pointless in this situation. I think the disease affecting your onions is downy mildew. The disease starts by causing the tips to yellow and die back and then grey mould will develop further down the stems and the plants eventually collapse. The bulbs will be soft too and won’t store. The spores of this disease can overwinter on autumn sown onions

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and can also remain in the soil for four or five years. The other problem is that there are now no sprays available to gardeners that can be used on onion crops. The only way to help alleviate the problem is to do what you have been doing, remove the infected leaves and burn them. Make sure there is no debris left on the plot which can harbour the spores. In theory a five year rotation should be put in place, but this will be tricky on an allotment site. Avoid growing overwintering onions as these will harbour the disease and then spread it to your summer crops. You should grow onion ‘Santero’ which has excellent resistance. You could also try ‘Tasco’ and ‘Golden Bear F1’ which are said to have very good resistance to downy mildew. Several supplieres sell ‘Santero’ and W Robinson and Sons sell ‘Golden Bear F1’ and Medwyn’s of Angelsey sells ‘Tasco’ (tel: 01248 714851).

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BRASSICAS www.premierpolytunnels.co.uk

Brassicas

Kale pest

Black Brussels

Q

Q

Can you tell me what is causing my Brussels sprout leaves to turn black? It is patchy over several leaves. This is a sooty mould, a fungal infection that grows on the sugary deposit left by sap sucking insects. These might be aphids or whitefly. Looking at your picture I think I can see some whitefly. The mould is not particularly damaging unless it is in copious amounts all over the leaves as then it can affect photosynthesis.

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I’ve grown some curly kale this year but when I came to harvest some leaves the other day the undersides were smothered in whiteflies. What can I do? Whitefly is a common problem on brassicas and, as you say, even worse on curly kale as you just can’t get at the little blighters! One top tip is to get yourself armed with a hosepipe and shake the

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plants then blast the cloud of whiteflies that emerges. It’s a temporary measure but if done regularly enough, you will reduce the numbers. Another way is to use one of those hand held vacuum cleaners and shake the plants then hoover them up. This is a most satisfying job. Apart from this, and regular spraying, there is little you can do. It might be worth covering the crop with Enviromesh another year.

Kale looking sick

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One or two of my kale plants are starting to look distorted, yellow and stunted. What could be the cause? I have fed the plants well? If you turn the leaves over you may notice grey mealy cabbage aphids (see page 10) a common pest of all brassicas including broccoli, swede and cauliflowers. This may be the cause or there could be another problem such as a soilborne fungus which may have got into the plant and could be causing yellowing and stunting. You could apply an insecticide to control the aphids but there is little you can do if the plant is infected by disease apart from remove the one or two plants that are showing symptoms and avoid growing brassicas on this spot for a year or two. www.kitchengarden.co.uk

July 2011

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Loose sprouts

Q

Why do Brussels sprouts open up and become loose rather than staying tight buttons? Technically known as blown buttons, which means they have started to open, it is a natural occurrence as they are just buds after all... but we prefer to pick them when they are nice and tight. Plant breeding has developed the sprouts to remain tight budded for some time giving us plenty of opportunity to pick them, but when the plant is stressed it may well cause the buds to open prematurely. Dryness at the roots and then heavy rainfall can cause a surge in water uptake and the buds blow. Unusually high temperatures will also advance bud opening and so too can a rich soil, so avoid overfeeding. You could take the tops out but the bottom buttons are probably more likely to blow even faster. I would remove the very tip of the plant if it is looking in good condition, this tastes as good as sprouts and in fact the blown sprouts can be harvested and cooked a bit like cabbage, so all is not lost.

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July 2011

Holey swede

Q

I’ve grown some swede this year but the seedlings have been attacked by a pest and got lots of holes in them. How do I control this pest? Swede is particularly prone to attack from flea beetle which feed on the leaves causing small holes and in bad cases the leaves look like lace doilies. You may spot the flea beetles if you brush your hand over the crop. They are called flea beetles because they jump when disturbed.

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Mealy cabbage aphid

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Can you tell me how I can control mealy aphids on Brussels sprouts? The mealy cabbage aphid is a real nuisance and has probably been more troublesome in recent times due to the warmer winters. In colder years the pest overwinters as eggs but in mild conditions the adult pest can continue and then get a head start in spring

You could use Westland Plant Rescue Fruit and Vegetable Bug Killer, or if you want to be organic you could buy some of those yellow sticky traps that you hang up in the greenhouse. These can be gently run over the top of the seedlings, just touching them slightly to disturb the flea beetles – many will get stuck to the trap. If the attack is not too bad the plants may grow through the damage and go on to produce a crop.

starting more generations of aphids. They cluster among the leaves especially in sunken puckered areas, so they are difficult to get at to control, but the only means is by using sprays such as Bayer Ultimate Fruit and Vegetable Bug Killer or Westland Plant Rescue Fruit and Vegetable Bug Killer. Other insecticides such as those containing fatty acids or plant oils may also help.

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Swede failure

Q

For many years I have been trying to grow swedes, one of my favourite winter veg, but why do I only get small thin roots? A lot of people seem to have trouble growing swede which is not surprising, it being a member of the brassica family. Certainly some soils seem better for swede growing than others. An alkaline soil is important, so maybe you should try a pH test and apply lime if necessary to raise the pH. Keeping the plants well watered but not overly wet is important. If living in an area that gets a lot of rain and you have heavy soil, then it is worth trying to grow them on a ridge to aid drainage. Keep pests at bay – which is easier said than done. Flea beetle and cabbage root fly are two of the first hurdles swedes have to overcome. Flea beetles can devastate the leaves, peppering them with tiny holes and basically stunting their growth or killing them, so keep them pest free and also thin out as soon as the seedlings are through to keep them well spaced – then in theory you should do a lot better. But as we all know, sometimes even the best gardening practices just don’t always work if the weather or the soil is just not conducive for a particular crop.

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Heartless cabbages

Q

Can you tell me why my cabbages haven’t got good solid centres? They look healthy enough. Cabbages which don’t ‘heart up’ can be caused by not planting them firmly enough. It’s made worse if the soil has just been dug over before planting, as it’s harder to firm in the young plants sufficiently. Another possible cause is a lack of humus or organic matter in the soil. Applications of garden compost or farmyard manure will help.

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Pots or seedbeds?

Q

I want to sow some cabbages and broccoli seeds but should I sow them in pots or in a seedbed? Seedbeds are a part of your veg patch devoted to germinating and nurturing young seedlings before they are lifted and planted into another part of the plot. Brassicas and leeks are often started off this way and many people swear by this method. However, some gardeners find the seedlings can be devastated by pests or inclement weather and so have more success starting off cabbages,

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broccoli and other brassicas and leeks in cell trays. The seedlings get their own little cell of compost which is a sterile growing medium so no danger of clubroot or other diseases taking hold. They can also be protected from bad weather and slugs. Once they reach a few inches high they can be potted on or planted into the plot and being that much bigger they can usually fight off pest attacks much easier. You could also make life easy and skip the seed sowing stage and buy in young vegetable plants.

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Composting Diseased crops in compost

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Can you put diseased crop material on the compost heap? In theory if you can make a good compost heap, made up of different materials and it is turned occasionally so that the compost heats up well, weed seeds and pathogens will be killed. The trouble is a lot of gardeners’ compost heaps just don’t ever get hot enough. If you know your compost heap is unlikely to warm up and you won’t be mixing up the layers then it is best to avoid putting on diseased foliage. The spores from many fungal diseases can survive a ‘cool’ composting process and end up being put back

on your soil. If you are allowed to have bonfires on your site this is the best method of getting rid of diseased material. You could keep an incinerator just for storing diseased waste and once it dries out burn it quickly. The other alternative is to put diseased waste in the dustbin, but this has environmental implications. Another alternative is to have a separate compost heap purely for really troublesome weeds and diseased foliage. This can be kept away from the other compost heaps and allowed to continually break down without putting the waste back onto the plot. However, the compost you do get could be bagged up and put on the ornamental garden away from your fruit and veg.


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Rats in the compost

Q

We have discovered a burrow beneath our compost bin and believe it’s caused by rats. How do we get rid of them without using poison? It certainly sounds like rats and generally they are not too bothered with the material put on compost bins as it has a vegetable origin – although some people add eggshells to compost bins which may entice the rats. One option is to use the plastic drum composters which are sealed except for small air holes. Also the compost bins that are bought from local authorities are good if you opt for the base. It is the base that will prevent rats from digging underneath and getting into the bin through the bottom. The base usually has small holes in it to allow liquid to drain. The only organic control is the ultrasonic devices that are said to repel rats too. There are battery operated ones available.

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Cucumbers Cool cucumber problem

Q

Some of my greenhouse cucumbers developed a type of rot that seems to start off as brown spots which get progressively worse and turn mouldy. What can be done? This sounds like gummosis. Infected fruits develop brown sunken spots on their surface which then ooze an amber-like gum. More mould then develops on these areas. It is a disease that can take hold in cool, wet conditions. Avoid watering too liberally early in the season when there are cooler temperatures. In the height of the summer watering can be increased. Although cucumbers like a humid atmosphere you need the heat with the moisture in the air but not too saturated at the roots.

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Sour cucumbers

Q

My cucumbers have flourished in my greenhouse but the only problem is they taste terrible – really sour and bitter. Why? Some open pollinated varieties that produce male flowers can then pollinate the female flowers which results in bitter tasting fruit. On these varieties it is best to remove the male flowers. Simply nip off with finger and thumb when they are still small. These are easily identifiable, just check behind the flower. If there is a small bump then this will indicate a female flower, if not then a male flower. There are many varieties now which produce all female flowers such as ‘Cucino’ a mini cucumber variety or ‘Carmen’, which also has good disease resistance.

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PEAS AND BEANS www.premierpolytunnels.co.uk

Peas and beans Runner bean stops

Q

Some of my runner bean plants have got small brown spots on the leaves which have a lighter yellow mark around them. What could be causing this? This sounds like halo blight, which is a bacterial disease carried on the seed and is more of a problem if you save and sow your own seed. The disease can cause stunted growth and the leaf symptoms show as small brown spots with a yellow halo effect around them. There are other bacterial infections that could affect beans but the brown spots tend to be larger with these. In a bad attack the pods may be marked too, but if they are not then they are fine to eat. Warm, wet conditions will make halo blight worse so avoid overhead spraying with water and pick off affected leaves. It is best to grow beans in a different place next year and don’t save any seed from the plants, instead start with fresh seed next season. You could try the variety ‘Red Rum’ which does seem to be more halo blight tolerant.

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Pinching broad beans

Q

Why is it recommended to pinch out the growing tips of broad beans? I have some quite tall plants now but am not sure if I should nip the tops off? One of the main reasons for removing the very growing tip of broad beans is to deter the dreaded blackfly attacking. This common pest of broad beans is particularly attracted to the young parts of the plant. If you remove the soft growing tips the plant is less attractive to the pest. Another reason for removing the tip is to force the plant’s energy into forming the pods and beans lower down the stem. Once the plant reaches a certain height and has produced about four flower trusses then you can remove the tip, diverting the energy to the beans.

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Pea grub

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Why are peas inundated with little grubs? Your pesky grubs were more than likely pea moth larvae. These small creamy maggots are spotted when you open the pod to eat your delicious peas only to see the brown frass and maybe larvae peering out at you. This is a troublesome pest, particularly on crops sown in early spring. Very early or late sown peas often escape the onslaught because

the adult pea moths are on the wing about now and if the peas are of the right maturity and are flowering, they will deposit their eggs so that the hatching larvae invade the developing pods. So it is at flowering time that you need to spray with a chemical such as Westland Plant Rescue Bug Killer Fruit and Veg RTU to kill the hatching larvae. Alternatively, alter your sowing times to avoid the main flight of the adults.

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Yellowing beans

Q

I have been growing some dwarf French beans in a polytunnel this year but the leaves have started to turn yellow and it is spreading, taking over the whole crop. What could be causing this? This could be the result of red spider mite attack. They are more likely to be troublesome in a warm, dry environment like a polytunnel. The first signs of attack are a yellow speckling of the leaves which eventually spreads and the plant can be killed in a bad attack. If you turn over a leaf and rub your fingers over the underside, you often notice a dusty deposit. The actual red spider mites are tiny but you can just about see them with the naked eye and they are beige in colour. Keeping this pest in check is difficult once it is established. You can try keeping the polytunnel

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Beans wilting humid by damping down the pathways and any bare patches of earth. Red spider mites hate a damp atmosphere. It would be best to remove the worst affected plants, taking them well away from the polytunnel and removing as much of the debris as possible. This pest can overwinter in cracks and crevices in the polytunnel and reinfect next year. Once you have cleared the polytunnel it might be worth using a horticultural disinfectant such as Armillatox to spray the woodwork and frame of the house and any wooden raised beds or permanent structures. If you get the problem next year you could order some biological controls to release a natural predator into the polytunnel. You would have to put up Enviromesh at the ends of the polytunnel or cover any side vents to prevent the predator escaping.

Q

I sowed some broad beans on the plot and most came through alright but a few have since wilted and keeled over. Would they have been too wet? This sounds like a case of bean seed fly. The tiny larvae are in the soil and they attack the seedling as soon as it emerges from the seed. Sometimes the seedling doesn’t even make it above soil level. Seedlings will suddenly wilt because the stems will have been nibbled. It seems to be early crops that are more susceptible. If it has been a problem then sow in pots and plant out when the plants are several inches high. The stems will be tougher and less likely to appeal to the bean seed larvae.

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Silver pods

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Can you tell me what is wrong with my peas? Some of the pods have what can only be described as silvery patches on them. This sounds like a case of pea thrip. The adults are tiny black flies that lay their eggs on the plants and the subsequent larvae feed on the peas and the lifting of the top surface of the pod gives the appearance of a silvering of the pod. There is little you can do at this stage but preventative sprays of Safer’s Insecticidal Soap or Bayer Ultimate Fruit and Vegetable Bug Killer may help if applied on future crops at flower bud stage. 16

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POTATOES www.premierpolytunnels.co.uk

Potatoes Potatoes blackenend

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I have started some potatoes really early in pots to see if I can get an even earlier crop. When should I plant them out? The problem with this method is damaging the soft stems or roots of the new plants when transplanting. If you damage these then growth will be halted and you will counteract any early sowing. With this in mind it might be best to plant out while still small with only a few inches of growth. That way you hopefully won’t do as much damage and they will grow away quickly. However, if planting them out in March you will need to cover the foliage with some fleece or gently cover the tops with soil to prevent frost damage.

Potato scab problems

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We had problems of potato scab on our allotment last year. Also many of the potatoes had hollows in them surrounded by brown flesh. We garden on light sandy soil but certainly ours were well watered. What can we do to avoid this? From your description is sounded like common scab rather than powdery scab, and as its name suggests is quite a common problem causing rough patches on the potato skin that can almost completely cover the tuber in a bad attack. It is certainly worse on sandy soils, which is what you have, and alkaline soils make it doubly worse. Plenty of organic matter added to the soil will help and keeping the potatoes moist at the time when the tubers are just starting to form is also important. You could try growing more resistant varieties like ‘Harmony’ or ‘Lady Christl’,’Premiere’ or ‘Nicola’.

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Holey potatoes

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I took on a new plot a couple of years ago which was covered in weeds and grass. I have managed to grow some crops last year including potatoes but many of them had small holes. Is this slug damage? It could be slug damage or it could be wireworm. Slugs usually cause more uneven edged holes in potatoes whereas wireworm causes very small neat round holes. The fact your plot is only recently cultivated from weeds and grass suggest it could be wireworm. This pest is the larvae of various click beetles and is particularly prevalent in grassland, so affects newly formed plots especially. One method of control that has been tried is sowing a mustard crop. It has shown to reduce the amount of damage by wireworms but it is not clear why. One theory is that the life cycle of the wireworm (which is long, taking up to five years to pupate) is speeded up but temperature is more important for speed of insect development. The other suggestion is the roots of mustard exude a chemical to control the wireworm. It would be worth trying a mustard crop on bare areas of the plot and digging in when still quite small plants (5-7cm/2-3in).

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July 2011

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Spuds a bit small

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I lifted a plant of early potatoes but they are really small. This is very disappointing as I have kept them well watered. Where have I gone wrong? The first earlies are supposed to be quite small, egg size or even slightly smaller. It could be that you have lifted them a little too early. You didn’t say when you planted them but generally potatoes are ready 12-15 weeks after planting. Have the plants started producing any flowers yet? If it is dry during the flowering period, this is the time when the tubers will be swelling, so soil moisture is more critical then. It is surprising how much water is required to really soak the soil down to the roots. Gardeners often sprinkle water over the leaves for a few minutes and think that will suffice, but if you test the soil you may find it is still quite dry. I would wait a week or two before lifting another plant and hopefully they may have increased in size.

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Keep potato blight at bay

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I had terrible problems with potato blight last year and have grown some more blight resistant ones this year but is there anything I can do now to prevent a bad attack? July onwards is usually the time of year when blight strikes. This disease can be sitting happily in the soil waiting for the right conditions to prevail and then it strikes. Warm humid days are perfect for spore germination. The British Potato Council has a blight incident alert service which you can register with and you can get alerts when your area is more likely to be at risk (www.blightwatch.co.uk). There is a measurement of blight incidence called the Smith

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Period which is a set temperature and humidity that is required for blight to be active. This is actually a period of two consecutive days when the minimum temperature is 10C (50F) or above and on each of these days at least 11 hours when the humidity is greater than 90%. This Smith Period is now monitored countrywide. It all sounds a bit extreme, but for commercial potato growers this is vital and we gardeners can benefit from the knowledge too. Not that there is a great deal we can do as we do not have the commercial sprays that the agricultural industry has. However, we can apply Bayer Fruit & Vegetable Disease Control during the danger periods. www.kitchengarden.co.uk


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Roots Green carrots

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The top of the root of my carrots are all green. I have been cutting this off as I am not sure if this is okay to eat. I know you shouldn’t eat green potatoes. Can you advise? You are fine eating green carrots, they are safe to eat unlike green potatoes. They belong to completely different plant families and potatoes belong to the solanaceae family of which all the green top parts of the plant are poisonous. You would have to eat a fair few green potatoes to make yourself ill but even so it is best to throw any green ones away. Carrots are fine though... but perhaps not that appetising once they turn green. It is the light getting to the exposed part of the carrot that causes it, so to avoid this in future earth up your carrots as they grow.

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Forked carrots

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What causes carrot roots to fork and become misshapen? I added manure and a light sprinkling of chicken manure pellets before sowing. The answer could be a bit too much fertiliser. If you manured the ground and added chicken manure before sowing this could have created too rich a soil. The effect of growing carrots on over-rich soil is forking of the roots which you describe. Ideally carrots should be sown on ground previously manured and then cropped with something else. It is a common problem and not one to worry about unduly, just avoid over feeding the ground before sowing carrots next year.

Parsnip problem

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My parsnips are a good size but I notice some have some brown markings on the skin. Will it affect the eating? This is a classic case of parsnip canker caused either by poor soil conditions or a fungus. You tend to see horizontal cracks which are a rusty brown colour and often near the shoulder. In time the cracks merge and get worse and the areas become sunken and blackened. If they are not too bad then you can simply cut away the damaged skin and eat as normal. There have been some advances in resistant varieties including ‘Albion’. Many seed suppliers including D T Brown and Mr Fothergill’s sell this variety and others with some disease

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resistance. It also helps to grow parsnips on different areas of the plot each year and avoid overcrowding so thin regularly.

July 2011

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Tomatoes To bag or not to bag toms?

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I am about to plant my tomatoes in the greenhouse but wonder if I should put them in growing bags this year as they were grown in the border soil last season and some did not do so well. Would this be a better idea? If you had problems growing tomatoes in the border soil, then it would be a good idea to grow them in growing bags or large pots this year. The compost in these growing bags is sterile and if the plants are kept well watered and fed, there is no reason why you should not get good growth and a decent crop. Growing in the border soil does involve greater risk. There are factors you have no control over, such as the presence of pathogens or pest eggs. Roots may be damaged which can reduce growth or allow infection in. On the other hand, growing in border soil allows the plant roots to venture further and there are often fewer problems associated with lack of water. If last year’s crop succumbed to blight, which is not impossible in a greenhouse but less likely, then there could be spores in the soil ready to reinfect the new plants.

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Tomato leaves curling up

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Why are the leaves of my tomato plants beginning to roll up. What is causing this? If your tomatoes are healthy and green then I would say it was high temperatures causing this. Sometimes in small greenhouses the temperature can reach incredible highs during sunny days, even in early summer, and this is the plant’s reaction to protect itself from water loss. Try and remember to open the vents and the door on sunny days and consider some sort of shading for the greenhouse. This could be the paint on white Bayer Coolglass or just some green netting.

Tomatoes splitting

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I have grown tomato ‘Sungold’ this year and it is producing a lot of fruit but a lot of these are splitting. Is there anything I can do to prevent this? This variety is particularly prone to skin splitting because the skins are so thin. It is made worse if the crops are ever dry at the roots and then watered causing a sudden rush of water and expansion of the cells rupturing the skin. It can also be extremes of temperature, especially later in the year when we have hot days but cooler nights. So there is not a great deal you can do but just pick them regularly and appreciate their thin skins.

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Caring for hanging baskets

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I have a 40cm (16in) hanging basket filled with three bush tomatoes but how often should I feed and water it? Baskets dry out really quickly in summer especially if densely planted. You may find you need to water the basket daily or even twice daily in the height of summer. It is best to keep the compost just moist rather than let it dry out and then try and water it or it will just run off the top. If tomatoes are denied water the fruits may develop sunken black marks on the base called blossom end rot. Feed your basket with a proprietary tomato food once or twice a week.

Black bottomed toms

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Why are the bottoms of some of my tomatoes turning black? This is a classic case of blossom end rot. The base of the tomato fruits turn black and sunken. It is caused by cellular breakdown in the fruit, due mainly to lack of calcium but it is irregular watering that interrupts the calcium delivery and so the best way to avoid blossom end rot is to keep a constant supply of moisture to www.kitchengarden.co.uk

Leggy seedlings

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Why is it my tomato seedlings always grow leggy and end up making weak plants that never really recover? I sow them in a propagator and then place on a south facing windowsill. There are many reasons for ‘stretched’ seedlings. The combination of too warm and not enough light is often the main reason. If seedlings are not removed quick enough from a propagator the stems will often elongate. Also, if you sow too early in the year the day length and quality of light is just not good enough so wait until March to start sowing. The advantage with tomato seedlings is you can transplant them into deeper pots and bury the stem up to the lowest leaves. This will instantly form a shorter plant and the buried stem will produce more roots which will be advantageous.

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the roots. This is often tricky when growing in pots or growing bags. On hot days these can dry out in hours and it only takes one dry spell to affect the fruit. Once the plants are watered the supply of calcium is replenished and this explains why some fruits will get blossom end rot and others will be fine, it just depends on the timing of the drought conditions.

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Blight on tomatoes

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Can I spray my tomatoes to prevent blight affecting them? They seem quite healthy at the moment but they got blight last year. I grow them outside on my plot. Tomatoes grown outside are particularly vulnerable to blight especially if there was a case the previous year. The spores of this disease can overwinter on dead plant material in the soil and rain splashes will lift the spores up to the stems of new plants to reinfect them if the conditions are right. It is best to apply any chemical sprays before you see the symptoms as they can prevent an attack but won’t cure it. Sprays of Bayer Fruit & Vegetable Disease Control will help, but if the conditions are perfect for the disease – such as damp and warm – then the plants may still succumb but the sprays will buy you time to hopefully get a crop. If growing tomatoes outside and you know there is a blight problem grow varieties such as ‘Ferline’ and ‘Legend’ which show good resistance to the disease.

Ripening tomatoes

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I have some tomatoes growing outdoors on my plot. I didn’t get them planted very early so the crop is rather late. The trouble is the fruit is not ripening very quickly. Can I help things along? This can be a problem with late outdoor tomatoes. As autumn approaches shorter days and less sunshine will slow up ripening. One method you could try is to remove the stakes and gently lay down the tomato plants onto some straw or cover the soil with some plastic. Then over the top of your row of flat plants, place some cloches. If you want to improve things further place a couple of ripening bananas under the cloche. The extra warmth and ethylene gas given off by the bananas will give a kick start to the tomatoes and they should ripen quicker.

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Tomato problems

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I have got some tomato plants in growing bags in a greenhouse. They are fruiting well but some of the fruits are cracking and have yellow patches on them as though they are not ripening evenly. What could be causing this? The fruit cracking may be due to temperature fluctuations between day and night time temperatures or it could be irregular watering. If the roots dry out and then get a sudden surge of water, it can split the skins but temperature is usually the problem. The pale patches on the fruit can be heat damage caused by scorching temperatures in the greenhouse during the day. It is worth shading the crop or perhaps damping down the floor in the hottest part of the day to cool the air.

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July 2011

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Fruit Watch out for sawfly

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Something has been eating the leaves of my gooseberry bush. Some branches have no leaves left. What is causing this? This sounds like a classic case of gooseberry sawfly. If you look closely you may see green caterpillars with black spots. They usually arrive around late spring to early summer and can defoliate a gooseberry bush in a matter of days. The gooseberry bushes can survive this onslaught but it may well affect a good harvest. The key to control is be ready for them and be vigilant. From mid-spring keep checking the bushes and at the first sign of attack spray with Westland Plant Rescue Fruit and Vegetable Bug Killer or Phostrogen Safer’s All Purpose Insecticide Ready to Use or just pick off the caterpillars. If you check your gooseberry now and there is no sign of caterpillars, they may have pupated. It is worth just giving the bush a feed and water to encourage the leaves to grow back and to make a note to check the gooseberry bush next spring

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Pruning plums

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I have quite a young fan trained plum tree. I haven’t pruned it at all yet and feel I should do this soon. How and when do I need to prune it? Plums and other trees in the same family, such as cherries, should be pruned in summer rather than winter as the disease silverleaf is more likely to attack in the colder part of the year. Fan trained fruit trees can be trimmed now to encourage more

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fruiting wood for next year. Ideally the thin whippy sideshoots growing from the frame should have been cut back in early summer to about six leaves. These subsequent shoots can be cut back now harder still to one leaf. As you didn’t prune these soft young shoots earlier in the summer do so now, pruning back hard. If there are any big gaps in the fan, you could leave one or two new shoots and tie these down to fill in the gap.

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Fluffy deposits

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I have an orange tree which is looking a bit sick. The leaves are dropping and there are black deposits on them. There is also some ‘cotton wool-like’ deposits on the stems. What is wrong with it? This sounds like a classic case of mealybug . The white fluffy deposits are a protective coating over the pests and their eggs. This pest sucks the sap of the plant and exudes a sticky deposit called honeydew that then attracts mould causing the black marks. In a bad

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Temporary planting

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I was wondering what the term ‘heeling in’ means. I have seen it referred to planting of fruit trees? ‘Heeling in’ is simply a term used to describe temporary planting. It is often used for bare rooted plants that are bought by mail order and they may arrive at a time you are not ready to plant them properly. To heel in a plant you simply find a bare piece of ground and dig a hole or even just loosen the soil and place your plants all together, no need to separate several sent as a bunch in the hole or on the ground, and cover

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infestation leaf drop is common but if there is only a small amount of mealybug then just simply remove with a cloth. If you have a real infestation of this pest in a greenhouse or conservatory then you could use a special biological control using a special ladybird called cryptolaemus – the large larvae of which actually look like the mealy bugs. This biological control needs high temperatures to work so can only be applied in late spring and through summer.

with a generous amount of soil to completely cover the roots. The plants don’t even need to be upright. In fact if they are laying down they are less likely to be blown down! If the plants arrive with very dry roots, it is worth soaking the rootball in a bucket of water for an hour before heeling in. This procedure will keep the plants healthy for a couple of days to give you the chance to get ready to plant them properly. This is only a temporary measure and it is no real substitute for getting a new tree or fruit bush planted straight away if possible.

Pear leaves damaged

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Can you tell me what is damaging my pear tree? The leaves seem to be covered in raised bumps and are turning brown. I can’t see any pests and I suspect it is a disease. This sounds like a case of pear leaf blister. It is caused by a pest but a microscopic one so it isn’t surprising you haven’t seen it. This pest feeds in the leaves in spring causing these green blister like contusions which later turn brown. It may look quite serious but in fact if the tree is well cared for and healthy in other respects, it will not unduly affect the tree or the crop. Remove the worse affected leaves and clear up any fallen leaves. There are no sprays that will be effective against this mite.

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Growing fruit in pots

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I would like to grow an apple tree in a pot. What size of container should I use and what compost is best? One of the biggest problems with growing trees in containers is their stability. They soon become top heavy and are easily blown over. Terracotta or concrete pots are heavier and more stable than plastic but the compost tends to dry out quicker. If using plastic put some stones in the bottom of the pot to help stabilise it. The minimum size you will need is 12-15in (30-38cm) diameter. Ideally 40-45cm (16-18in) is better. Put a few inches of crocks or stones in the base before filling with John Innes No. 3 compost. This is loam based and heavier than other composts and doesn’t tend to dry out so quickly. Your young tree should be fine for a couple of years in this pot as long as you scrape away the top few inches of compost each year and top dress with some fresh compost with a sprinkling of controlled release fertiliser added. After two or three years the tree will need to be removed from this pot (in winter) and some of the roots trimmed away and repotted into fresh compost, or planted into a larger container.

Grease is the word

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When do I apply grease bands to my fruit trees? I have heard these can stop pests from reaching the branches. Grease bands are applied in mid autumn around the tree trunk to protect fruit trees from pests such as winter moth. The wingless female of this species emerges from its chrysalis in autumn, about November time or later into December and January. The female climbs up the trunk to the canopy where she mates and lays her eggs. The hatching larvae then feed on young leaves and flower bud clusters in spring. Any grease band you put around the tree should be flush with the bark and continuous around the trunk with no breaks or the pest could get through. Look out for Bio Boltac Grease Bands, Agralan and Vitax also do special glue which can be applied straight onto the tree. These are particularly good for older trees with gnarled, lumpy bark.

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Planting fruit trees

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Is it too late to plant an apple tree in spring or early summer? I have read it is best to do this when they are dormant in the winter. If you buy fruit trees by mail order from specialist nurseries they tend to be field grown and are lifted when conditions are right between about November and March. The trees are bare rooted and if planted immediately on receipt will hardly notice their great move. Once the buds start to open from March transplanting trees by this method is not to be recommended. However, trees grown in pots can still be planted as the roots are self contained and are less disturbed when planted. Most garden centres sell their fruit trees in containers and check out specialist nurseries to see if they are still sending out stock or have containerised trees. In theory you could plant a pot grown tree at any time of the year, however, it will be less of a shock for the tree if you can plant it during its dormant season.

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Summer prune

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I have a cordon apple tree that has some fruit on it but also a lot of new growth. Should I remove some of this and when? As this picture shows, soft new growth often bursts out all over on apples and pears by this stage in the summer. Those new shoots that are not required to extend branches and the overall framework are simply ‘extra’ foliage and can be trimmed back to one leaf above where there is a basal cluster of leaves. This is the point where the new season’s growth started from. If the shoot is coming direct off a main trunk or branch they it can be cut back to three leaves above the basal cluster.

Thinning apples

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What is ‘June Drop’ and are other fruits apart from apples affected? The June drop can affect all tree fruits – in particular apples, pears, cherries and plums – but it doesn’t always happen in June of course (although with apples that is roughly the time it happens). It is a perfectly natural phenomenon as it is the tree’s own mechanism for shedding fruit it can’t sustain. You should wait until this event happens before thinning your apples and then only if you feel the tree is still holding a lot of fruit. Some more may still be shed so don’t thin too heavily and aim to reduce the density of fruit giving space between fruitlets rather than just randomly removing fruit. The aim is to get fewer larger apples. It is probably better to just let nature take its course and enjoy big and small apples as nature intended.

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Spotted apples

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Our apples are suffering from what I think is bitter pit. What can we do to remedy this please? Your apples are indeed suffering from bitter pit. This causes slightly sunken and discolured spots on the surface which run through to the tissue below. When you peel the apple you will see the corresponding brown spots of flesh. It is something that can develop during storage but occasionally apples on the tree are affected. It’s amazing to think this problem is related to blossom end rot in tomatoes. Both conditions are caused by a deficiency in calcium that is often due to to lack of water at a critical time in the fruit’s development. It is a little more complex than that of course as a high concentration of potassium or magnesium can exacerbate the problem. Just like the human body plants are complex

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Apple choice

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I was going to buy an apple tree but there are so many varieties to choose from, I just don’t have a clue which one to get! I do like red apples, which narrows it down a bit. This is not an easy one to answer because as you rightly said there are so many varieties to choose from. It is always best to get yourself along to one of the annual Apple Day events in October where you can often try several varieties. As it is too late for this now, I can suggest a couple that might be ideal. As you said you like red apples I can recommend ‘Katy’. This apple has a wonderful red flush on it and I really like its crispness of flesh and with a slight sharpness about the flavour. It is also one suggested for more northern gardens. It is an early variety.

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Olive tree care organisms and any imbalance can cause health problems. The key to avoiding this in future is to keep the tree watered during periods of drought from June when the fruit is swelling. Spray calcium nitrate (1oz in two gallons of water) in June and repeat about three more times at 10 day intervals.

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I’ve got a small olive tree in a pot which I have moved into a greenhouse for the winter. Should I put a heater in the greenhouse on really cold nights? Your olive tree should be fine in an unheated greenhouse. They can survive temperatures down to -10C in theory, although obviously this is not ideal! In a greenhouse it may get below freezing in really cold weather but the olive should be fine. In the south or mild western regions you could get away with keeping the olive outdoors in a sheltered part of the garden, so long as the winters are mild, otherwise move the plant to a conservatory or unheated greenhouse. It is also important not to overwater the plant. Keep the compost only just moist to keep the plant ticking over. If it is too wet, the roots could rot.

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Another worth a mention is ‘Scrumptious’, which is a mid season apple. It has been bred in the UK and is very hardy so ideal for your part of the world. It is also free fruiting even on a small tree and it has a good red flush on the skin too.

July 2011

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Shrunken grapes

Q

I have a grapevine in a greenhouse that produces a lot of grapes, but some of the bunches don’t form fully with some of the grapes small and withered. What is causing this? This is caused by a disorder called grape shanking. Some of the fruits do not grow to their full potential or even shrivel up on the vine. It can be caused by more than one problem but generally it is thought to be a poor root system which could be damaged by waterlogging or even soil compaction and poor nutrition. To try and alleviate the problem next year, loosen the soil a little around the top of the plant and avoid overwatering the plant. As the fruits are forming spraying with a foliar feed may help.

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Pruning blackcurrants

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How do I prune a very old blackcurrant bush? The principle behind pruning blackcurrant bushes is to reduce the number of stems, let more light into the centre of the bush and also remove any low lying branches on the outside of the bush. You should probably aim to remove about a third of the stems. Start by taking out the oldest, thickest stems. Cut them back to as near ground level as you can. Remove any really very thin, poor spindly stems and also any damaged shoots. Any stems almost laying on the ground or very low on the outside of the bush can be cut out completely. After this has been done just remove any badly crossing stems. You will probably find this will give the bush a new lease of life and it should produce more fruit. However, if it doesn’t it may be time to dig it up and plant fresh stock.

Scab control

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Can you suggest a suitable spray to control apple scab and when should I apply it? Apple scab is a common disease causing brown patches on leaves and the surface of the fruit. It is best to use preventative sprays as using a fungicide after you see the damage is really too late. Early spring, when leaves start to unfurl is a good time to

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start a spray programme against fungal attacks. Suitable chemicals include Bayer Systhane Fungus Fighter or Fruit & Vegetable Disesae Control. If your apples have apple scab then make sure all fallen leaves are removed from around the tree in autumn. This will prevent spores overwintering and reinfecting the tree next year.

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Planting strawberries

Pruning tip bearer

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Can you tell me how I should prune my ‘Bramley’s Seedling’. I have been told it is a tip-bearing variety? ‘Bramley’s Seedling’ is a partial tip-bearer which means it produces a lot of its fruit at the ends of one year old wood. A spur bearer fruits on older wood on small knobbly spurs. Most varieties of apple are spur bearers but if pruning a tip bearer then just concentrate on keeping the framework of the tree open and remove any badly crossing branches. Thin out excess shoots and take out one or two of the older branches if necessary to encourage younger fresh growth which will bear the fruit. The best time for major pruning is when the tree is domant between November and March.

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Pot on fig

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I have a fig tree in a small pot and it needs potting on or planting in the garden. What should I do with it? Fig trees can be happy growing in pots for several years as long as they get adequate moisture and a little feeding occasionally, although not too much. However, they do make large trees and prefer a decent sized pot to allow good top growth and fruiting potential. I would replant your fig into a pot at least 38cm (15in) diameter and then after a couple of years into a slightly bigger pot. If you want to plant it in the ground then be aware that it could grow 41⁄2m (15ft) or more. You can contain it better if trained against a wall and a south facing one is best. You can contain the tree roots by sinking four paving slabs into the soil at the base of the wall and back filling with crocks and soil. If growing in a pot use John Innes No. 3 compost and place some crocks or stones in the base to aid drainage.

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I want to plant a bed of strawberries but want it to be easy maintenance so thought I would put down a sheet of plastic or something first and plant through. Is this a good idea? Planting strawberries through a membrane is a good idea as it keeps the moisture in, the weeds down and keeps the strawberries clean to so you don’t need to put straw down. It does need to be a semi-permeable membrane though, not a plastic sheet. This will keep the vital moisture out. Special ground cover membranes are available from most garden centres and usually by the metre. The bed is prepared first, removing as many perennial weeds as you can and breaking up the soil with a fork. Add some well rotted compost or manure and incorporate well. The membrane can be placed over the soil and the edges buried beneath the soil to hold it down firmly. Cross slits are cut into the membrane at about 30cm (12in) intervals and you can plant the strawberry plants through these. Only bury the solid crown of the plant about halfway in the soil and water in well.

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Raspberry pest

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I love raspberries but my fruits always seem to get little maggots in them which is very off putting to say the least. Is there anything I can spray to prevent these attacking the fruit? This sounds like a case of raspberry beetle. It is usually noticed in the grub stage when we pick the fruit and the stalk end may show grey rotted areas and inside we find a small maggot among the frass. To control this pest we need to get to the root of the problem much earlier. This is flowering time

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Strawberry blooms turn brown

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I have noticed that one or two flowers on my strawberry plants have turned brown. Not all are affected just one or two. What could have caused this? The flower buds dying back on strawberries could have been caused by blossom weevil. The adult beetles partially sever the stalk after laying eggs in the buds. The buds then wither and turn brown and may drop off with the developing larvae inside. Another pest called strawberry rhynchites can attack the flower stems causing them to die back before opening. The damage done by these pests is usually minimal so just nip off any dead or dying stems and wait for the undamaged ones to produce fruit.

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when the adult beetles are on the wing and laying their eggs. So any time between May and mid-July when raspberries will be flowering is the danger period. Other fruits such as blackberries and tayberries can be affected too. Spray blackberries and other hybrid berries when most of the petals have fallen from the flower. You could spray raspberries then too but perhaps another good time is just as the fruits start to turn colour. Spray with Bayer Sprayday Greenfly Killer when the first pink fruits are seen and again two weeks later.

Blueberry care

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I have a couple of blueberries in pots but wonder if they should be moved into a bigger pot now. They have been in the same container for a couple of years. They look healthy enough and I have been feeding them. Your blueberry bushes may require moving into the next pot size but it depends on the size of container they are in now in relation to the size of shrub. If the plants look top heavy in comparison to the container and if roots can be seen through the holes in the bottom then certainly move them into a bigger pot. Otherwise, they may be fine for one more year before moving. It would be a good idea to top dress your blueberries with some fresh ericaceous compost or a mix of garden compost, soil and a sprinkle of flowers of sulphur to maintain the acidity. You may need to scrape away some of the old compost first. Finally cover the new soil with some pine needles or bark to help conserve moisture. If blueberries need moving into a larger pot you should use a proprietary ericaceous compost rather than try and guess an acidic mix of your own. Just peat is acidic but has very little nutrient value so should not be used on its own. Blueberries will eventually get to at least 1.5m (5ft) high and round if grown well and the size of pot required for this size of plant is about 50 litres (11 gall).

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FRUIT www.premierpolytunnels.co.uk

Blotchy raspberries

Q

A couple of my raspberries developed mottled yellow leaves this summer. Only a couple of them seemed to be affected what could be causing this? This sounds like a virus which can cause yellow mottling of the leaf in conjunction with stunted growth. Once the plants are infected there is nothing you can do except grub these plants and hope the other canes haven’t been infected.

A

Trim figs

Q

Can you tell me if I should prune my fig tree? It is in a large pot but it has three main shoots and they don’t seem to be producing many sideshoots? Figs are best pruned in early spring but during the growing season you can remove just the growing tips of the branches. This will help encourage branching further down the stems. Sideshoots which have grown long enough to produce five leaves can also have their tips removed. Don’t overdo it as the plant may bleed and die back.

A

www.kitchengarden.co.uk

Why kiwi never fruited Aphids can transmit virus diseases but there is also a soil dwelling nematode that can pass on a virus to cane fruit. If it is the latter then other canes along the row may develop the disease. If this is the case then it would be better to lift the row and replant fresh stock in another part of the garden. It is probably best to wait until next summer to see what happens, you may find the rest of the row does not become infected.

Q

I have had a kiwi growing up the wall of my garage for about three years but it has never flowered or produced any fruit. Is it in the wrong place do you think, it gets plenty of sun? This is not an uncommon problem with kiwi fruit and could have one or two causes. You did not mention the variety but if it is not ‘Jenny’, a self-fertile variety, then it may be one that requires a mate! Another popular choice to grow in the UK is ‘Hayward’ because it is very late flowering so misses the frost but it will require the prescence of a male variety to get it to fruit. This could be the problem or perhaps the plant is not in a south or south west facing aspect which is necessary to provide mild and sunny conditions. Your location is not too bad for growing kiwi, especially with the milder winters we have been experiencing. Pruning can also affect fruiting and should be done with care. Once you have a framework of branches you trim back sideshoots to two buds beyond where the last fruits were in winter. In your case pinch out the growing tips of the sideshoots to encourage fruit bud growth. The other problem is late frosts damaging the ends of the shoots and any flowers that do form, so protect with some fleece now if nights are forecast to be cold. It is worth noting that kiwi plants outside do take quite a while to mature so in fact your plant is a relative youngster and may not produce fruit until it is about five!

A

July 2011

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Q&A INDEX

General vegetable Coriander – growing in pots Veg for small gardens Bolting spinach 5 Hardening off tender vegetables Slug control Whitefly problem in greenhouse Compost for raised beds 6 Red spider mite on aubergines Rabbit control Weed control – bindweed 7 Alliums Rust on leeks Allium leaf miner Damping off 8 Bolting onions Downy mildew 9 Brassicas Sooty mould on Brussels sprouts Whitefly on kale Aphids 10 Loose Brussels sprout buttons Flea beetle on swede Mealy cabbage aphid 12 Swede – best growing conditions Cabbage - not hearting up Cabbage – starting off in pots or seedbed 13 Composting Putting disease material on compost 4

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July 2011

14 Rats in compost heap Cucumbers Gummosis Sour cucumbers 15 Peas and beans Halo blight – runner beans Blackfly – broad beans Pea moth larvae 16 Red spider mite on beans Pea thrip Bean seed fly – broad beans 17 Potatoes Potatoes in pots Common scab Slug/wireworm 18 Small new potatoes Potato blight 19 Roots Green carrots Forked carrots Canker – parsnips 20 Tomatoes Growing bag versus border soil Tomato fruit splitting Leaves curling up 21 Blossom end rot Growing in hanging baskets Leggy seedlings 23 Tomato blight Fruits cracking and yellow spots Ripening problem

Fruit 24 Sawfly – gooseberries Pruning plums 25 Mealybug on orange tree Heeling in fruit Pear leaf blister 26 Growing apples in pots Using grease bands 28 Planting fruit trees Summer prune apples June drop and fruit thinning 29 Bitter pit – apples Choosing apple varieties Olive tree care 30 Grape shanking Pruning blackcurrants Scab – apples 31 Prune tip bearing apple Potting on fig Planting strawberries through membrane 32 Raspberry beetle Strawberry blossom weevil Blueberries in containers 33 Virus – raspberries Kiwi not flowered Trim figs www.kitchengarden.co.uk



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