greenhouses I shade net I hydroponics I aquaponics Polyethylene covered hoop houses over a strawberry project. Being in the Western Cape with low levels of hail and less wind in this particular area, the cover could last as much as six to eight years with proper management.
Cover of a Greenhouse
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dust and dirt in areas where open land farming or dusty winds prevail. This may reduce the amount of light entering the greenhouse. It is important to clean polycarbonate to abate algae on the inside and outside of the greenhouse. Also, it is advisable to have lawn grass around the greenhouses. Polycarbonate sheets are more expensive than 6 mm poly, but not as expensive as glass covering (which is very seldom used in SA!). The hoop roof construction is covered with polyethylene. How do you define “Best Greenhouse Film” and which do you think is best? The following are some practical areas of consideration. • What price? If a low cost film is what you are looking for, then 6 mm plastic films will be the better option greenhouse film due to its relatively low initial cost. What you save in the initial film investment you will lose to
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labour cost. 6 mm greenhouse film will not last very longer than four years, and may not come with much if any of a guarantee. You will be replacing that film due to aging from the sun, or a storm ripping a hole in the film. • The Energy Considerations: The price of heating and cooling your greenhouse is the second biggest expense beside the labour of constructing and covering your greenhouse. Which covering offers the best heating and cooling R-value? Obtain at least four quotations. • Estimated UV Lifespan: For the plastic films, how much do you value having a UV guarantee. Some companies offer a 10 year full warranty. Does your plastic films supplier offer this warranty? The big secret is to purchase a film with a proven track record elsewhere in the world. • Adverse conditions: What is the best
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JANUARY/FEBRUARY 2021 VolUmE 18 No 1
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HYGIENE
DISEASES
SCoUTING
CUCUmBER
Hygiene in the fresh produce packhouse Page 4
Pythium disease on greenhouse crops Page 11
Scouting for pests and diseases Page 14
Improving cucumber yield Page 18
greenhouse covering when it comes to wind, hail and snow load? If this is important to you, compare the various suppliers’ warranty records. • How cover replacement labour influence you: Should your greenhouse cover be damaged by a hail storm or excessive wind, tearing the cover; which greenhouse cover is the best in offering you a cost saving when repair or replacement is required? Most greenhouse films will require you to recover the entire structure. Some suppliers offer strips, so in the unlikely event there is damage to the cover, you will only be replacing a single or two sections and not the whole structure. Basically; the above considerations and more are to be made when deciding to select a greenhouse cover for your structure to obtain optimum production and longevity in structure cover. JS
ADDRESS: CODE: CONTACT NUMBER: Account Name: Nufarmer Pty Ltd t/a Undercover Farming Bank: First National Bank, Kolonnade Branch Code: 25 10 37 Account No: 62007699806
Undercover farming I
January/February 2021
I Volume 18 No 1 19
