General information on copper compounds used as fungicides in Kenya

There are many copper compounds used as fungicides in Kenya. Recommended is Bordeaux mix which is a combination of copper sulphate and hydrated lime (calcium hydroxide).  Other compounds include Copper oxychloride and Copper hydroxide. The latter two are now commonly used and are commercially available.

Copper fungicides were formerly accepted in organic farming provided that the number of applications was strictly followed and a proper soil amendment is observed to prevent copper accumulation in the soil, and can still be accepted with permission from the certifying authority.

In wet weather fungicide sprays should be applied as soon as the disease is observed or as soon as local experience suggests that weather conditions are favourable for disease development.

Crop scouting should be used as a guide in making a decision on whether to apply a fungicide. And when applying fungicides, safety procedures in application must be complied with, particularly, in use of protective clothing. Observe right dosage and prescribed pre-harvest intervals. Ask your local agricultural extentionist on locally registered fungicides.

Bordeaux mixture is primarily a fungicide that controls bacterial leaf spots, blights, anthracnoses, downy mildews and cankers. It also repels many insects. The compound is labelled for use on many vegetables, tree fruits and nut crops.

Bordeaux mixture, as with sulphur and lime sulphur, can be phytotoxic to plants. If applied in cool, wet weather, it may burn leaves or cause russeting of fruit.

Bordeaux mix spray

Materials needed to make a gallon mixture

• 3 ½ tbsp of copper sulphate
• 10 tbsp of hydrated lime
• 1 gallon of water (4 litres of water)
• Wooden stick
• Plastic bucket

How to prepare?

1. Add copper sulphate and hydrated lime in water. Make sure to use plastic container
2. Stir well using a wooden sick or ladle
3. Protect self from direct contact with the solution

How to use?

1. Spray plants thoroughly preferably early in the morning, in a dry and sunny day. In this way, the plants have the time to dry and the solution can not penetrate into the leaves’ tissues
2. Constantly shake the sprayer while in the process of application to prevent the solution from clogging

Pest controlled

1. Flea beetles on tomatoes and potatoes
2. Anthracnose
3. Bacterial blight
4. Bacterial wilt
5. Black spot
6. Downy mildew
7.Early blight of potato and tomato
8. Late blight on solanaceous crops
9. Powdery mildew
10. Rust

Copper fungicides in the Kenya market

Copper products below listed are registered in Kenya by the Pest Control Products Board www.pcpb.or.ke. These products are readily available in most agro-vet shops in the country. It is advisable for organicfarmers to consult their respective certification agencies prior to use. According to the Soil Association (UK) www.soilassociation.org copper is “restricted” and can be only used where the need is recognized by the Soil Association Ltd (UK). Other organic certifying agents have differing rules.

Table 1: Copper fungicides commercially available in Kenya 

Standard procedures for the preparation and application of homemade copper products

1. Monitor plants regularly and spray only when necessary.

2. Read and follow the label instructions carefully, particularly, dosage, pre-harvest intervals and safety measures. Ask for assistance from your local extension agriculture office, if unsure.

3. Spray in the early morning or late afternoon.

4. Wear protective clothing when handling pesticides and during application. Wash your hands after handling of pesticidesand application. Do not eat, drink or smoke when handling and during application of synthetic pesticides including copper.

5. Do not have a direct contact with the crude extract while in the process of the preparation and during the application.

6. Make sure that you place the product out of reach of children and house pets while leaving it overnight.

7. Harvest all the mature and ripe fruits before product application.

8. Always test the product formulation on a few infected plants first before going into large scale spraying. When adding soap as an emulsifier, use a potash-based one. Gun soap (Kenya) is recommended

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