When wheat farmers visit agro vets to control leaf wheat rust on their crop, they will find that one of the most widely used fungicides for the disease has been banned and only one alternative is available.
According to the Pest Control Products Board (PCPB), Kenya imported 411,371kg of chlorothalonil fungicide between 2018 and 2021. However, its entry into Kenya has been outlawed since July of last year and it can no longer be sold in local agrovets from 31st December of this year. Chlorothalonil has been critical in controlling fungal diseases such as rust in wheat, broccoli, and French beans; early & late blight in potatoes and tomatoes; coffee berry disease (CBD) in coffee; powdery mildew and downy mildew, and botrytis in roses and broccoli; angular leaf spot and anthracnose on French beans; leaf spot, black leg and clubroot in cabbages.
For Kenyan wheat farmers, the Chlorothalonil ban means only one other fungicide, Tebuconazole, is left to fight off leaf rust in wheat. Wheat leaf rust which affects seven of every ten wheat farmers and causes up to 100 per cent in losses is among the the key diseases responsible for Kenya’s falling wheat production which has been dropping by one-tenth every year for the past six years.
Related News: Locally produced seed shortage driving farmers out of wheat
Related News: Millet bread a silver bullet to halve Kenya’s wheat imports and slash bread prices
Related News: Wheat blast spread to cut global production 13%
Chlorothalonil is classed as practically nontoxic by the United States Environmental Protection Agency (USEPA) and has been used across the world since 1966 with no reported effect on human health or the environment. The pesticide has however now been banned in Kenya to keep agricultural exports to the European Union (EU) open. Despite there being no study that shows that chlorothalonil has any negative effects, the EU sphere of influence is banning chlorothalonil on a data gap because of the smallest measurable amount (measured in parts per billion) of another chemical derived from it found in water. Although no tests have ever found an environmental risk from Chlorothalonil, campaigners argued that this derived chemical had not been fully tested for risks in its own right– so Chlorothalonil was banned.
Chlorothalonil is highly used by Kenyan farmers because, unlike its alternatives which are not as effective, it’s among the few fungicides for which diseases cannot easily develop resistance. This is because it targets various parts of fungus and all the channels they feed on crops.
According to Joseph Wangai, a wheat farmer and former cereals agronomist at Twiga, the withdrawal of Chlorothalonil means farmers are left with Tebuconazole fungicides that are used for preventing wheat leaf rust and Flutriafol fungicides used for both curing and preventing the diseases. “It is important to ask at your local agrovet whether the fungicide you are buying is for preventing or curing leaf rust or if it serves both purposes.
Tebuconazole pesticides available for wheat leaf rust in the market include Bayer’s Folicur, Amiran’s Orius, and Jojemi’s Dokta Cure. Advanta and ADAMA Ltd have combinations of both curative and preventative Tebuconazole fungicides.
Wangai further counseled farmers living in low-altitude regions of Laikipia, Nyandarua, Nakuru, Nyeri, and parts of Uasin Ngishu which are most affected by the fungus to use leaf rust-tolerant varieties that need half as much spraying as the ones that are not.
These include the fast-growing Kasuko, Planet, and Hawk, which are all adapted to lower-altitude parts of Kenya.
However, rust spreads rapidly and over long distances from one farm to another as the fungi produce many spores that are carried by the wind or on clothes. It also easily forms new fungus strains that attack resistant wheat varieties meaning scientists have to develop rust-resistant wheat every five years.
According to Jackson Maina, a wheat agronomist based in Timau wheat leaf rust is already difficult for farmers to manage as it begins from the base of the crop making it difficult to scout. Meanwhile, the cost of spraying a hectare affected by just 20 per ent of the disease can cost farmers up to Sh15,000.
Related News: Markets: Local wheat prices to rise 40% on limited supplies, as imports fall
Related News: Factsheet: Tackling wheat leaf rust– Kenya’s most devastating wheat menace
“The wheat leaf rust fungus is very aggressive and easily develops new fungus strains that attack previously resistant kinds of wheat. It usually takes two years for leaf rust to build resistance if only one fungicide is used. While large-scale farmers can find ways of smuggling chlorothalonil pesticides from neighbouring countries, for smallscale farmers I’d recommend farmers rotate every wheat harvest with crops from the Gramineae family or for them to plot ways of exiting wheat whose production cost has more than doubled in the past few years to cheaper to produce cereals like maize whose farmgate price has increased or remained relatively similar,” he said.
Chlorothalonil is one of the eight pesticides banned by the Kenyan government, the others include Pymetrozine, Thiacloprid, Diuron, Propineb, Chlorpyrifos, 2,4-D, and Acephate which threaten the sustainability of wheat, potato, tomato, maize, coffee, chilli, cabbage, cucumber, and eggplant farming.