Organic production is possible in a greenhouse

Is it possible to do organic greenhouse farming? Yes, it is possible to produce crops organically using a greenhouse. Production, however, requires a lot of care to prevent and control common crop diseases and pests in the greenhouse.

Apart from flowers and fruits, one of the most important crops that farmers prefer to grow under greenhouse conditions are tomatoes. Tomatoes are prone to many diseases and pests. To grow them successfully, you will need to start by selecting a suitable place to put up the greenhouse to minimize the threat of diseases. The diseases and pests that affect tomatoes in a greenhouse are outlined below:

Diseases

1. Bacterial wilt: This is a devastating disease that is caused by bacteria called Ralstonia solanacerum. The disease has no known cure. Bacterial wilt affects all crops in the potato family including tomatoes, chillies, capsicums, eggplant and bananas. The disease can only be controlled through crop rotation. For a farmer who wants to put up a greenhouse especially for tomato production, selection of the site to set up the greenhouse is very important. Select a site where none of the crops mentioned above have been grown for up to five years. Alternatively look for a new site where no crop has been grown before. Soil tests for bacterial wilt are very expensive and are therefore not a good option for most small scale farmers. No plants in the potato family should be planted near the greenhouse.

2. Early and late blight: Tomatoes are prone to early and late blight. To control these diseases most farmers use chemicals. All chemicals are prohibited in organic farming except copper oxychloride (Cupravit®WP) you can spray this chemical at least once a week throughout the growing period.

Pests

Pests are easy to control in a greenhouse since the environment is controlled. A greenhouse has screens that keep out pests. But workers entering the greenhouse have to ensure the screens at the entrance do not allow pests to get in by keeping the screen doors closed at all times. Whiteflies are usually the most troublesome pests in greenhouses. To control them, place insect traps such as yellow sticky polyethylene papers all round the fence around the greenhouse and even inside it to trap insects like whiteflies.

Farmers can then use organic inputs such as those prepared using plant extracts (See TOF issue No. 17, Plant extracts special edition). If well prepared, plant extracts combined with growth activators such as EM1 can boost crop health and create resistance against diseases. Except for labour, the cost of organic green house production is low compared to conventional greenhouse production. For farmers who would like to buy organic inputs for greenhouse production, there are many organic fungicides, nematicides and biopesticides available in the market that they can use. The table below shows some of the inputs farmers can use:

Stage of growth	Stage of growth	Dosage	Spraying	Application method
Before planting	Biox500	200ml	1 litre/ 90 m2	Drench (allow 2 days before planting
Seed treatment	Trichotech Mytech Vitazyme	2.5g 2.5g 5ml per kilo seed	-	Mix the seeds with and dry under shade
At Planting	Agriorganic (6:7:7) fertilizer	400kg/litre	-	Apply in planting holes furrows and mix well with soil
Two weeks after planting and up to flowering	Vitazyme Radiant	50ml 10ml in 20 litres of water	8-12	Spray the mixture to run off