COMMON pests and diseases that stop Kenyan farmers produce from reaching the export market
It is the dream of every farmer to export their produce for higher returns. However, many face phytosanitary and technical challenges that lead to rejection of their produce by exporters.
In the last few weeks, the European Union has been sensitising farmers on what is needed in the export market through a project dubbed the Standards and Market Access Programme, which is implemented by United Nations Industrial Development Organisation, Kenya Plant Health Inspectorate Services (Kephis), and Kenya Bureau of Standards, among other stakeholders.
James Wahome, the Acting General Manager, Phytosanitary Services at Kephis, breaks down the pests and diseases that stop farmers from exporting their produce and how to overcome them.
False Codling Moth (Thaumatotibia leucotreta)
This is a major pest, because the larvae of the moth feeds on a wide range of crops such as cotton, capsicum, macadamia nuts and citrus. The brown insect originated from Sub-Saharan Africa, but has also been detected in Europe and US. It thrives under warm and humid conditions and can produce up to five generations annually.
They are most active during the night and once the larvae enter the fruit, they are difficult to detect.
One should observe good sanitation conditions, destroy wild and cultivated hosts and apply recommended insecticides, which could be done aerially or from the ground. Scout at least twice a week for early detection and work with your agronomist to apply the necessary pesticides.
Leaf miner (Liriomyza spp)
It is the larva of an insect that lives and eats the leaf tissue of plants. Adult leaf miners are small, active, black and yellow. Leaf miners attack numerous horticultural crops including tomatoes, cucurbits, peas and beans.
They can be detected by seeing mines on leaves. Manage them through crop rotation and use of abamectin-based chemical. However, I must warn that the leaf miner is resistant to many chemicals.
These are small pests that feed on the undersides of plant leaves. They have the ability to carry and spread diseases, thus, they are a huge threat to food security globally. White flies spread diseases such as African cassava mosaic virus, bean golden mosaic virus, tomato yellow curl virus, tomato mottle virus and sweet potato chlorotic stunt virus.
They have needle-like mouth parts used to sack sap from phloem and they excrete honey dew, a sugary liquid from plant stems and leaves.
If in large population, white flies can cause leaves to turn yellow, wither and fall off.
Use reflective mulches which repel them especially in vegetable gardens as well as yellow sticky traps. Destruction of white-fly infested vegetables after harvest is highly recommended to stop spread of the pest.
Fruit flies (Bactrocera invadens)
This disease came to East Africa from Sri Lanka and invaded the whole of Sub-Saharan Africa, thus earning the botanical name invadens.
To stop its detrimental effects to the fruit business, the industry uses cold treatment to get rid of the larvae.
Common hosts of the pest are citrus, mango, cashew, papaya, guava, pepper and a number of wild plants.
Fruit flies are managed by use of pheromone traps. Kephis, for example, has established fruit flies free zones in some mango growing areas through use of these traps. Clearing of nearby bushes and proper sanitation of the orchard is vital to keeping fruit flies at bay.
Bacteria Wilt (Ralstonia solanacearum)
The disease is caused by a soil-borne bacterium that colonises the xylem, in a range of plants. When it occurs in tobacco, it is known as Graville wilt.
Ralstonia solanacearum causes bacterial wilt in tomato, pepper, eggplant and Irish potato.
Symptoms include withering of leaves, some shoots or the whole plant even when there is ample moisture in the soil. It is also characterised by browning and necrosis of the vascular ring and rotting of tubers, producing a foul smell.
The infection is spread through planting of infected materials as well as on infected soil. Therefore, crop rotation and planting disease-free seedlings would help prevent this infection.
The pest can breed 10-12 generations annually. In its lifetime, each female can lay 250-300 eggs. Its infestation has been reported on tomatoes, potatoes, and common beans.
Tuta absoluta can be managed by use of sex pheromone traps, which attract the male moths.
It is also advisable to clean nearby bushes as they may act as hiding and breeding places. Always destroy infected crop.
Other harmful organisms to watch include African bollworm (Helicoverpa armigera), and Mango seed weevil (Sternochetus mangiferae)
By Rachel Kibui
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