Lesson 10
Lesson 10 Part A: Part B: Part C:
GARDEN FRIENDS AND ENEMIES ORGANIC PEST CONTROL ORGANIC PEST AND DISEASE TREATMENTS
Lesson: 10 - Part A
GARDEN FRIENDS AND ENEMIES Today’s lesson is about pest control. Don’t forget your hat and gloves.
If you saw any of these little creatures on plants in your garden, what would you do? If you decided to spray them or squash them, it would be a great loss to your garden because all these little creatures are the children of different types of ladybirds. Ladybirds and their children (larvae), eat a lot of garden pests, including aphids and scale insects. When a ladybird larva has eaten thousands of aphids, it attaches itself by its tail to a strong leaf or stem, unzips its skin along its back, and appears in an armoured or spiky shell. This is the pupa stage of an insect’s life where the insect grows its adult wings and legs inside its protective covering. Ladybird larvae only stay in the pupa stage for about a week before unzipping their shell once again and this time appearing as an adult ladybird. As soon as its wings are dry, it is ready to fly away to find more garden pests to eat. Because of the way they stick to leaves and stems, many gardeners mistake the pupae of ladybirds for sap-sucking pests. We all know what the common spotted ladybird looks like, but different types of adult ladybirds come in different colours and patterns. Some, like the ladybird at left, don’t have any spots at all. The more unusual ladybirds and many of their strange-looking larvae and pupae are killed every day by people who mistake them for garden pests. The white fluffy larva above is at great risk because he looks just like the pest that he feeds on.
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Lesson: 10 - Part A cont: So, before you start getting rid of garden pests, it is a good idea to find out who your other garden friends are, and who your garden enemies are!
Bees are important visitors to gardens because they transfer pollen from flower to flower.
Pollination allows flowers to form fruit. Bees come in different sizes and some of our native bees are very small. The large, furry Leaf-cutter Bee chews circles and ovals out of tough leaves to make a nest for its young, but it does little damage to the garden.
Hoverflies look like wasps that hover in mid flight like tiny helicopters. These helpful flies and their larvae eat a lot of different insect pests.
Frogs are garden friends that eat lots of insect pests. Frogs come in many different colours and
sizes, but they are all helpful in the garden. You may not know that you have frogs in your garden as many only make a noise on warm nights, or when it rains.
Praying Mantids are helpful too. They sit patiently with their front legs folded as if they are praying while waiting for garden pests to come their way.
Spiders and lizards eat lots of garden pests. The small spiders that are sometimes seen on corn plants are especially helpful. They eat the eggs that the corn earworm moth lays deep in the tassels on corn cobs where sprays can’t reach
Birds can be both helpful and a nuisance in the garden. Some birds do an excellent job of eating both large and small insect pests. Others like to feed on your seeds and ripening crops. You may have to cover some of your crops with netting to keep them safe from nuisance birds. Australia has a lot of different kinds of wasps too, and some are like tiny flies. Wasps that build nests of papery tubes can get very angry if you go too close to their nests, but most wasps don’t sting and are very helpful visitors to gardens. Wasps pollinate some flowers; mud wasps collect garden pests to feed to their babies in the odd-shaped nests they build from wet clay, and some, like the tiny, newly-hatched wasps in the photo, lay their eggs in garden pests. If you see their cluster of small cocoons on the leaves of broccoli and cabbages – don’t destroy them.
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Lesson: 10 - Part A cont:
Attracting garden friends You can make bees, birds, frogs and lizards welcome by keeping some clean water for them to drink, as you learnt in Lesson 7. Adult wasps, hover flies and some birds need nectar from flowers for food. Some of our native shrubs produce nectar. Perhaps you could find a spot in your school grounds for a Banksia or Hakea
shrub that flowers in winter when there aren’t many flowers. Bees collect pollen and nectar, and ladybirds need some pollen too, before they lay their eggs. Grow some flowering annuals in your garden or school grounds to keep your garden friends visiting regularly.
Lesson 10 – Part B
ORGANIC PEST CONTROL Organic gardeners take a different approach to pest control because sprays (including some organic sprays) that kill pests will also kill your garden friends who are working hard to get rid of pests. If you kill the insects, frogs or birds that help you control any pests that you have now, you will have more pest problems in the future.
The first rule of organic pest control is – don’t panic! When you see that your plants are being nibbled or damaged, take some time to watch what is happening. Who is eating whom, or what? Are your garden friends at work among the pests? If so, don’t spray the pests! Have a close look at your plants to find out why they are being damaged. Only stressed plants are attacked by pests. Healthy plants have everything they need to make the smells and tastes that keep pests away. When a plant is being attacked by pests it produces a smell that signals other plants nearby to make the smell and flavour compounds to keep pests away. Many of these compounds are antioxidants that protect our health. If you rush to spray the pests, plants won’t need to make these antioxidants. Dig a small hole about 15 cm deep near the roots of a plant that is being attacked and have a look at what is happening in the soil. There is always a reason why pests appear in large numbers on particular plants, or certain plants get diseases. Most of the time your garden soil will provide the answer to your pest or disease problem.
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Does the soil have enough humus? If not, add some compost or worm castings to the soil surface and cover it with mulch. If you did not have a lot of compost when you were preparing the bed, did you give the bed enough complete plant food? Is the soil damp all the way down to the bottom of the hole? Plants can only soak up plant food that is dissolved in water. If the soil is dry, they can’t get enough food or water to stay healthy and are very likely to be attacked by pests or get diseases. Water plants more carefully, using the methods you learnt in Lesson 7. Do your plants have a lot of soft, sappy growth? Snails, slugs, aphids, scale and some fungal diseases love plants with this type of growth, which appears when plants are given too much fertiliser, especially liquid fertilisers that contain a lot of nitrogen.
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Lesson: 10 - Part B cont: Does the soil pH suit the plants that you are growing? If you remember, in Lesson 9, you learnt that plants can only soak up food when the soil pH suits them. Get rid of the pests and adjust the pH to suit your crops to avoid future attacks. Are your plants wilting easily? If dry soil or poor drainage are not the cause, your plants may have a ‘wilt disease’. You will have to remove the plants and dispose of them in a sealed garbage bag. Don’t put them in the compost where they can spread the disease. Make the soil healthy again by using a longer crop rotation and adding plenty of compost to garden beds.
Lesson 10 – Part C Organic pest and disease treatments If you follow the methods that you learnt in previous lessons, you should have very few pest and disease problems in your school garden. However, severe weather conditions can also cause stress to plants, so here are some simple organic recipes that you can use if your garden friends are being outnumbered by pests. Please note – All plant protection treatments that require wetting leaves should be applied early in the day so that leaves can dry before dark. This is especially important for plants that have hairy leaves (for example, zucchini).
Aphids Aphids are attracted to soft, sappy growth that is caused by too much fertiliser, or lots of stormy weather. Some aphids spread virus diseases that can’t be cured, so these tiny pests should not be ignored. Clusters of aphids can be blasted off plants with a jet of water from a hose or a spray bottle with the nozzle set to ‘stream’. If you blast them with water before serious damage occurs, your garden friends will be able to control the survivors. If aphid attack is very severe, you can
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If you can’t see the cause of the problem by looking at your soil – perhaps you are trying to grow plants that don’t like the heat or cold where you live. If you try to grow plants that need cool weather to do their best in a place where it is always warm, or try to grow tropical plants where it gets very cold, these plants will attract pests and are more likely to get a lot of diseases. If you are not able to give them more comfortable conditions, it is best to avoid growing these plants in your garden or you will be kept busy looking after their many problems.
dissolve just enough fine potting clay in the water in the spray bottle to make the water cloudy. Too much clay will clog the spray nozzle. The clay will suffocate them – and your insect friends, too – so spray carefully! Get rid of weeds around your garden area, because aphids use weeds as hiding places.
Snails and slugs These creatures can be a nuisance in damp conditions. Birds, lizards and frogs like eating them, so don’t use snail pellets that can poison your garden friends. Snails and slugs are attracted to soft, sappy leaves and strawberries. They like ‘yeasty’ smells too, and you can trap snails and slugs in a plastic jar that contains a spoonful of Vegemite dissolved in half a cup of water. Dig a shallow hole in the bed and position the jar as shown in the drawing. Put some mulch over the top of the jar to keep it dark and stop it from getting hot.
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Lesson: 10 - Part C cont: A simple trap for snails and slugs is a wet earthenware plant pot placed on its side on garden beds, or you can trap them in citrus halves that have been squeezed for juice. Cover the traps with mulch, and remove your catch each morning.
Caterpillars Caterpillars are the larvae of moths and butterflies. Caterpillars often eat leaves and fruits of plants that don’t have enough water. Make sure you water more thoroughly and use mulch to help prevent water evaporation. Regularly check under leaves close to fruit for insect eggs. Squash any small caterpillars that you find, and scrape any eggs from leaves. Looper caterpillars (above) feed underneath leaves and lie along stems where they are hard to see. The first sign of a problem may be small ‘windowpanes’ appearing on leaves. These caterpillars can be knocked to the ground and squashed, or squash them on the leaves. Budworms and Corn Earworms attack water-stressed plants. Cut off the corn tassels after they have gone brown and have started to dry out, or use a paintbrush to dab some organic-allowed oil onto the end of the tassel closest to the cob to discourage the moths from laying eggs. These caterpillars also attack stressed tomato plants. You have to get rid of these caterpillars when they are very small. Once they move into fruit or flower buds, they are difficult to control. Destroy any damaged tomatoes, as the pupae of these pests can survive in compost heaps.
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Cabbage White Butterfly and Cabbage Moth caterpillars are hard to see because they are a similar colour to the leaves, and they lie along leaf veins. Removing eggs and small caterpillars will prevent them from doing a lot of damage if there are too many for your garden friends to control. Keep your plants well-watered; make sure the soil pH is suitable for cabbage family plants (violet crop rotation group), and grow dill between your seedlings to deter pests from this family of plants. However, if any caterpillars have become a serious problem, an adult should spray both sides of leaves with an organic-allowed caterpillar treatment, and take better care of your crops to prevent further pest attacks.
Leaf-eating Ladybirds These are the only ladybirds that are pests. They attack water-stressed plants in hot, dry weather. Eggs are laid under leaves, and the larvae feed underneath leaves making leaves look patchy. Adults feed on top of leaves, and are easy to see. If you think these ladybirds are causing damage in your garden – count the spots. The helpful spotted ladybird has only 18 spots; the leafeating pests are more yellow and have 26 or 28 spots. In the photos below, you can see the eggs, the prickly larvae, and the adult of this pest. Squash all of these while you are wearing gloves, or knock the adults and their larvae into a soup tin with some methylated spirits in the bottom of it, and scrape the eggs from the leaves. Then give soil around your plants a thorough watering and remove blackberry nightshade weeds.
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Lesson: 10 - Part C cont: Bean Fly These pests are tiny, glossy, black flies that appear in warm, humid weather to attack French bean plants that don’t have enough potassium. The best way to avoid these pests is to practice crop rotation, have plenty of compost in the bed where you grow French and climbing beans, and to hill-up soil around the stems of bean plants. Look out for yellow spots and fine lines on bean leaves. They are a sign that the flies have laid eggs in the leaves. Remove and destroy damaged leaves to stop larvae tunneling to the base of the stem, and give your bean plants a drink or two of organic-allowed seaweed tea.
A good plant tonic If your plants have a disease, a good general remedy is to spray the leaves with a solution of organic-allowed seaweed tea at the recommended strength. The chemical treatment for many plant diseases contains sulphur, copper, potassium or manganese. Seaweed contains all these minerals, and spraying the leaves helps plants to absorb them quickly, and improve their natural resistance to disease. After watering, give the soil around affected plants a drink of seaweed tea, too. Spraying leaves with organic-allowed seaweed tea can also help by providing important minerals quickly where pest attack is caused by not enough plant food.
Mildew diseases Don’t spray or dust mildewed plants with sulphur because it will damage plants that don’t get enough water, or when temperatures are above 30° C. It will also kill helpful ladybirds, including the bright black and yellow ladybird (at left) that eats powdery mildew and other bad fungi.
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Downy mildew causes spots on the top of leaves and a furry white growth under the leaves. This type of mildew is caused by poor air circulation around plants that don’t have enough potassium. Mix one part of organic milk with nine parts of water and spray both sides of the leaves. Full cream milk works best because the fat in the milk helps the spray stick to leaves. Also give soil around the plants a drink of organic-allowed seaweed tea. Powdery mildew is caused by a different family of fungi, and appears as grey-white powdery spots that keep spreading across leaves. This disease can be controlled with German chamomile tea. For each 500 ml of spray that you need, soak one chamomile teabag in a cup of boiling water for 15 minutes, then remove the teabag and carefully pour the tea into a spray bottle. Add a cup of cold water to make 500 ml of spray. Remove and destroy leaves that have lots of mildew, then spray both sides of the remaining leaves early in the day so that leaves have time to dry before dark. Give soil around affected plants a drink of organic-allowed seaweed tea.
Blossom-end Rot If your zucchini, melons or pumpkins start to grow, then turn yellow and become soft, they have blossomend rot. This is not a disease. It is the same problem that you learnt about in Lesson 9. On tomatoes, capsicum and eggplant, it causes sunken black patches on the end of the fruit opposite the stem, and it causes celery to go black in the centre of the bunch. Blossom-end rot is caused by not enough calcium in soil or by allowing the soil to dry out so that plants can’t soak up calcium when they need it. There is not much that you can do to rescue celery once it has been damaged. However, on other affected plants, remove damaged fruit so that new flowers will grow, and adjust the soil pH – if necessary. Use some upturned, large juice bottles that you learnt about in Lesson 7 to make sure that water goes through the mulch to the root area of these plants.
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