Comprehensive Guide to Pests and Diseases Affecting Wheat Farming in Kenya
Wheat farming is one of the main agricultural activities in Kenya, providing income and employment opportunities to many farmers and stakeholders throughout the value chain. The crop is mainly grown in the Rift Valley, with Nakuru and Narok counties being the major wheat-producing regions. Other areas engaging in wheat production include Uasin Gishu, Trans Nzoia, and West Pokot.
Wheat is an important cereal crop and a staple food for many people in Kenya and the world. The crop is used to produce flour, which is a key ingredient in making bread and other baked products. Wheat is also used to make animal feed and beer, among other products.
In recent years, the government and private sector have been promoting wheat farming in other regions such as Nyandarua, Laikipia, and Meru. These areas have favorable climatic conditions and access to irrigation, which is essential for successful wheat farming.
One of the challenges facing wheat production in Kenya is the limited availability of irrigation infrastructure. Many farmers rely on rain-fed agriculture, which is unreliable due to unpredictable weather patterns. However, with adequate investment in irrigation, improved seed varieties, and good agricultural practices, wheat farming has the potential to substantially increase yields and contribute to food security and economic growth.
The government and other stakeholders have been working to address the challenges facing the sector. For example, the government provides subsidies to farmers to enable them to purchase certified seed, fertilizer, and other agro inputs at subsidized prices. The private sector has also been investing in wheat research and development, producing high-quality seed varieties that are resistant to pests and diseases.
To reap the benefits of wheat farming, farmers need to adhere to good agricultural practices such as choosing the right wheat varieties, using certified seeds, proper land preparation, timely planting and harvesting, and proper storage of the harvested produce. Additionally, farmers need to have access to markets where they can sell their produce at competitive prices.
Wheat varieties in Kenya
Successful wheat production depends on knowledge about suitable varieties for the area where wheat production is planned. The varieties which are recommended have good stem rust resistance, are medium to high yields and have acceptable baking quality. To reduce risks due to seasonal climatic variation, it is advisable to plant at least 3 of the recommended varieties.
List of some recommended wheat varieties in Kenya:
| Variety Name | Altitude (m) | Yield (t/ha) | Days to maturity | Special attributes |
| “Kenya Pasa” | 1800-2400 | 2.3-6.7 | 130 | High yielding, resistant to lodging |
| “Kenya Chiriku” | 1800-2400 | 2.6-6.0 | 130 | Resistant to rust |
| “Kenya Mbuni” | 1800-2400 | 2.8-6.0 | 130 | High yielding |
| “Kenya Kwale” | 2100-2400 | 2.8-6.7 | 130 | High yielding, tolerant to sprout |
| “Kenya Popo” | 1800-2400 | 1.3 | 140 | Goodย toleranceย to stem, ear and yellow rust.Good tolerance lodging but poor to sprouting |
| “Kenya Fahari” | 1800-2400 | 1.1-1.6 | 120 | Resistant to Russian wheat aphid |
| “Kenya Kongoni” | 1800-2700 | 1.3-1.6 | 130 | Acid soil tolerant |
| “Kenya Nyumbu” | 1800-2700 | 1.3-1.8 | 130 | Resistant to stem rust |
| “Kenya Nyangumi” | 1800-2100 | 25 | 130 | – |
| “Kenya Paka” | 1800-2100 | 24 | 120 | – |
| “Kenya Kulungu” | 1800-2400 | 30 | 145 | – |
| “Kenya Nungu” | 1800-2400 | 24 | 122 | – |
| “Kenya Mbeha” | 1800-2100 | 28 | 130 | – |
| “Kenya Tembo” | 1800-2100 | 32 | 128 | Lodging resistant |
| “Kenya Mbega” | 1800-2100 | 3.0-6.8 | 135 | High yielding, resistant to leaf rust |
| “Kenya Duma” | Below 1800 | 2.0-3.4 | 82 | Drought tolerant, early maturity |
| “KS Mwamba” | 1500-2400 | 2.0-5.6 | 125 | Wide adaptability. High yielding |
| “KS Simba” | 1500-2400 | 2.5-5.0 | 116 | Suitable for both marginal and high potential areas. High yielding. Good baking quality |
| “Njoro BW 1” | 1800-2400 | 2.2-4.7 | 95 | Drought tolerant. High protein content. Early maturity |
| “Njoro BW 2” | 1800-2400 | 3.7-8.0 | 115 | Acid soil tolerant. Resistant to lodging |
| “Farasi” | 1800-2400 | 2.5-5.0 | 119 | Resistant to most foliar diseases. Good baking quality |
| “Ngamia” | 1800-2400 | 1.8-3.6 | 100 | Drought tolerant |
| KS Kanga | 1800-2500 | 1.8-3.8 | 110 | Tolerant to glume blotch, ear rot, stem rust. Good tillering ability, good baking and milling quality. |
| Eagle 10 | 1800 -2100 | 6.5 | 105 | Good resistance to stem rust, early maturity, very good baking quality |
| Kenya Pelican | 2100-2400 | 8.5 | 125 | Resistant to stem rust and yellow rust. Good bread making quality. |
| KS Wheat 04 | 1800-2500 | 3.85 | 110 | Good stem rust resistance, resistant to lodging, red coloured hard grains. Good for milling and for home baking |
Source: KEPHIS seed variety list
Examples of wheat varieties in Tanzania
- “Azimio” (altitude recommended: 1200 – 1800 m; grain yield: 1.8 – 3.0 t/ha; resistant to leaf, stem and yellow rust)
- “Juhudi No. 1” (altitude recommended: 1700 – 2200 m; grain yield: 3.0 – 4.0 t/ha; maturity: 90 – 110 days; resistant to leaf, stem and yellow rust andย Septoriaย leaf blotch)
- “Kware” (altitude recommended: 1300 – 1400 m; grain yield: 2.0 – 3.0 t/ha; moderately resistant to leaf, stem and yellow rust and Septoria leaf blotch)
- “Lumbesa” (altitude recommended: 1000 – 2000 m; grain yield: 3.5 t/ha; moderately resistant to leaf, stem and stripe rust)
- “Njombe 6” (altitude recommended: 1500 – 2400 m; grain yield: 2.1 – 4.1 t/ha; maturity: 110 – 120 days; highly resistant to leaf, stem and yellow rust)
- “Njombe 7” (altitude recommended: 1500 – 1800 m; grain yield: 3.0 – 4.2 t/ha; maturity: 110 – 120 days; highly resistant to leaf, stem and yellow rust,ย Fusariumย spp. andย Septoriaย spp.)
- “Riziki C 1” (altitude recommended: 1000 – 2000 m; grain yield: 3.5 t/ha; moderately resistant to leaf, stem and stripe rust)
- “Riziki C 2” (altitude recommended: 1000 – 1500 m; grain yield: 2.7 t/ha; moderately resistant to leaf, stem and stripe rust)
- “Sifa” (altitude recommended: 1700 – 2300 m; grain yield: 4.5 – 5.0 t/ha; moderately resistant to stripe rust andย Septoriaย leaf blotch)
- “Tausi” (altitude recommended: 1280 – 2400 m; grain yield: 2.0 – 4.0 t/ha; susceptible to leaf, stem and yellow rust)
Examples of wheat varieties in Uganda
- “Kenya Chiriku” (refer to Kenya list)
- “Nkungu” (grain yield potential: 2.0 – 3.0 t/ha)
- “UW 309” (grain yield potential: 2.0 – 3.0 t/ha; resistant to major diseases)
- “UW 400” (grain yield potential; 2.0 – 3.0 t/ha; resistant to major diseases)
Comprehensive Guide to Pests and Diseases Affecting Wheat Farming in Kenya
Russian wheat aphid (Diuraphis noxia)
Cereal aphids, being vectors of virus diseases, such as the Barley yellow dwarf virus, can be serious pests in wheat. The important cereal aphids that attack wheat in Kenya includeย Schizaphis graminum, Sitobion avenae, Rhopalosiphum padi, R. maidis, Metopolophium dirhodumย andย Diuraphis noxiaย (the Russian wheat aphid).
Theย Russian Wheat Aphidย (Diuraphis noxia) is one of the most damaging pests of small grain cereals (e.g. wheat, barley, triticale, rye, and oats) in the world. This aphid is a relatively new pest of wheat in Kenya. It was first identified in farmers’ fields in 1995. It then spread quickly to all the wheat growing areas of the country and it is nowadays the most important pest of wheat and barley. It is also a major pest in South Africa, but has maintained minor pest status in Egypt, Sudan and Ethiopia.
The Russian wheat aphid is pale to light green in colour with an elongated, spindle shaped body and grows to up to 2 mm long. It has short antennae with rounded very short, nearly invisible cornicles. The feature that easily distinguishes it from other cereal aphids is the presence of an appendage above the cauda, which gives the aphid the appearance of having 2 tails.
They prefer to live in the leaf whorls or in tightly rolled leaves, and thus are partially protected fromย natural enemiesย and from contact insecticides. They are hardy and can survive extremely low temperatures. Dry weather favours rapid increase of the aphid.
Unlike many important cereal aphids, the Russian wheat aphid is not a known transmitter of diseases, but causes damage by injecting a toxin into the plants during feeding. This toxin prevents the production of chlorophyll and causes, in susceptible cultivars, leafย chlorosis, longitudinal leaf rolling and white/yellow (warm weather) or purple reddish (cold weather) streaking on the leaves. Extensive chlorosis leads to death of plants while leaf rolling retards plant development causing stunted growth.
The tight rolling of flag leaves delays ear emergence, leading to floret sterile heads resulting in reduction of seed set. Aphid infestation also reduces the quality of the seeds produced, as shown by low kernel weight, increased rate of seed deterioration under accelerated ageing conditions, and reduced seedling vigour. The effect of infestation on seed quality is more pronounced under dry conditions. Infestation also may result in reduced seedling vigour.
In Kenya, the damage usually appears when crops have attained the tillering stage. Yield losses ranging from 25 to 90% have been reported.
What to do:
- Scout your crop regularly. Check for damage signs (first noticeable sign is slight to moderate yellowing of small areas of crop within the field; in addition the crop may appear to be under drought stress, even if there is no drought.).
- Use the correct seed rate to ensure good plant density, as low plant densities are susceptible to heavy attack by the aphid.
- Plant as early as possible for your area.
- Provide good growing conditions for the crop. A crop that is not stressed is more tolerant to aphid attack.
- Remove volunteer plants and grasses because they act as the aphid’s hosts even before the main crop has been planted.
Rats
Rodents, mainly the black rat (Bandicota bengalensis), also damage stored seeds.
What to do:
- Traps can be set but care must be taken to ensure they are placed in locations where livestock and children will not interfere or get hurt by them.
- In areas of Tanzania farmers reported spreading the leaves of the local shrub ‘intwinti’ as a repellent.
- In Western Kenya a mixture of cow dung and pepper is made, placed in the burrows and then burnt to smoke the rodents out.
- Do not kill mongoose, snakes, owls and other birds as they are very good predators of rats.
Birds
The red-billed quelea is a small weaver bird native to sub-Saharan Africa and renowned for its attacks on small-grain crops within Africa. It is the most numerous bird species in the world. The red-billed quelea is mainly granivorous, except when feeding its chicks insects or when eating insects prior to migration or breeding, and it relies on a supply of grass seeds to survive. When unable to find grass seeds or when opportunities arise, quelea will attack crops such as wheat, millet, oats, sorghum, teff, rice.
It is a major pest throughout much of sub-Saharan Africa and can cause significant economical losses.
The bird is inherently nomadic and this nomadism accounts for its invasions into areas where it was previously absent.
What to do:
- Use of Early Warning System
- Scaring of birds. Wheat farmers have found that stringing aluminium or bright coloured plastic strips that move with the wind across the wheat fields can act as a deterrent to quelea and weaver birds. If this cannot be found others employ young boys with a long rope to patrol the field and snap the rope as a whip whenever the birds try to settle and eat in an area.
Yellow rust (Puccinia striiformis)
The disease is also called stripe rust. Yellow or orange-yellow pustules develop on the glumes or chaff, on the leaves, and on the leaf sheaths. These lesions are arranged in parallel lines along the leaves. The disease may also attack the stems and the kernels. Infected leaves show distinctย chlorosis. Damage to the disease is most serious, if plants are attack at milk stage or earlier. Under severe infection kernels may be shrivelled. Rapid disease spread is favoured by warm weather with frequent rainfall. Yellow rust also attacks barley, rye, and over 60 species of grasses.
- Plant resistant varieties, if available.
- Control weeds.
- Avoid cropping of wheat in succession.
Brown leaf rust (Puccinia recondita f. sp. tritici)
The lesions are brown at first and are most easily distinguished from those of stem rust by their size and shape: they are usually small and circular. They turn black as the crop matures. They occur on the leaf blades and the leaf sheaths and may appear at any stage of the crop’s growth.
What to do:
- Plant resistant varieties, if available.
- Control weeds.
- Avoid cropping of wheat in succession.
Wheat bunt (Tilletia tritici)
Infected plants have reduced height. The smutted wheat heads are bluish green when theyt emerge from the boot. The healthy heads are yellowish green. The disease also induces excessive tillering. The spores are blown by wind to developing ears which they invade. Bunt infected flowers have green ovaries while healthy ones are white. The grain of wheat is replaced by a black mass of spores (spore ball) accompanied by a smell like of rotting fish.
What to do:
- Use certified diseased-free seeds.
- Plant resistant varieties, if available.
Take-all disease (Gaeumannomyces graminis)
It is a soil-borne fungus. It invades and blackens the roots, frequently killing them in the process. Affected stems are black and shiny just above the soil level. This symptom can only been seen by peeling away the leaf sheaths. The disease occurs in slowly widening patches, and in these areas plants with poorly filled or empty ears (whiteheads) may be present. The pathogen survives between crops on cereal roots and stubble. It also attacks barley, oats and rye.
- Rotate with non-susceptible crops such as alfalfa, sweet clover or maize.
- Remove stubble from the fields.
- Avoid continuous cropping with wheat, barley, oats or rye
Glume blotch (Phaeosphaeria (Leptosphaeria) nodorum)
It can cause considerable damage in wet years, especially where wheat has been grown for several years in succession. Symptoms consist of brown lesions on the glumes and around the nodes. At advanced stage of the disease black spots just like dots can been seen on the lesions. These are fungal spore bodies (pycnidia). The affected leaves become shrivelled with light brown patches on them. Glume blotch is spread by use of infected seeds, rain splash and infected crop residues.
- Use certified disease-free seeds.
- Burn stubble and crop debris after harvest.
- Rotate with non-susceptible crops such fodder grasses or maize.
Barley yellow dwarf virus (BYDV) (luteovirus)
Symptoms include leaf discolouration from tip to base and from margin to centre. The discolouration takes on different colours depending on the plant. In barley, the leaf turns bright yellow; in oat, an orange, red or purple discolouration is seen and in wheat, rye and triticale, the infected leaves are generally yellow and sometimes red.
Plants are usually stunted, with a decrease in tiller number and biomass and a weak root system. Suppressed heading, sterility and failure of grains to fill occur in the most severe cases. In the field, symptoms appear usually as yellow or red patches of stunted plants. The disease is most damaging in terms of yield reduction, if it infects a crop at an early stage of growth. The virus is spread by cereal aphids (e.g.ย Rhopalosiphum padi, R. maidis, Sitobion avenae, etc.). It is neither seed-borne nor mechanically transmitted. It also attacks maize, rice and several grasses.
- Plant resistant varieties, if available.
- Control aphids.
- Control weeds
Western flower thrips (Frankliniella occidentalis)
The Western flower thrips (Frankliniella occidentalis). (Close-up) Inmmature thrips (left) and adults. Very much enlarged . Real size 0.9 to 1.1 mm.
- ย control weeds
- regular scouting of thrips
Powdery mildew (Erysiphe graminis f. sp. tritici)
White powdery growth appears on all above ground parts of plants. The white growth consists of fungal mycelium and spores. The growth later turns buff in colour. The disease is wind-borne.
- Plant resistant varieties, if available.
- Remove crop debris after harvest.
Stem rust (Puccinia graminis f. sp. tritici)
It is characterised by pustules (a pimple-like or blister-like structure) that develop and break through the surface of the stems, leaves, sheaths, chaff and beards of the wheat plant. The kernels are badly shrivelled, many of them being so light and chaffy that are blown out with chaff in threshing.
The remaining grains may be shrunken to one-half or two-thirds normal size. Myriads of brick-red spores escape from the pustules and are carried by the wind to other wheat plants. Wheat stem rust also attacks barley, occasionally rye and many wild grasses (Hordeum spp., Agropyron spp., Elymus spp., Hystrix spp. and some brome grasses). It does not attack oats.
- Plant resistant varieties, if available.
- Plant early.
- Control wild grasses.
- Avoid cropping of wheat in succession.
Recommendations:
- Integrated Pest Management (IPM) Approach: Implementing an integrated pest management approach is crucial for sustainable pest control. This includes combining various strategies such as cultural practices, biological control, and judicious use of pesticides. It helps minimize the reliance on chemical treatments and promotes long-term pest management.
- Regular Monitoring: Regular monitoring of wheat fields is essential for early detection of pests and diseases. Conduct frequent field visits to assess plant health, check for pest populations, and identify disease symptoms. This allows for timely intervention and effective control measures.
- Crop Rotation: Practicing crop rotation helps break the lifecycle of pests and diseases. Avoid planting wheat in consecutive seasons in the same field. Instead, rotate with non-host crops like maize, legumes, or grasses. Crop rotation disrupts pest and disease cycles, reduces pathogen buildup, and improves soil health.
- Residue Management: Proper management of crop residues plays a vital role in disease prevention. Remove and destroy crop residues after harvest to reduce overwintering sites for pests and pathogens. Incorporate residues into the soil or use them for composting to facilitate decomposition and minimize disease carryover.
- Seed Selection: Choose certified and disease-free seeds from reputable sources. Opt for wheat varieties that have resistance or tolerance to prevalent pests and diseases in your region. Resistant varieties offer an effective defense mechanism against specific pathogens, reducing the risk of infection and yield loss.
- Sanitation Measures: Maintain good field hygiene by removing weed hosts and volunteer wheat plants. Weeds can serve as alternate hosts for pests and diseases, leading to their proliferation. Additionally, destroy any infected plant material and debris to prevent the spread of diseases.
- Educate and Train Farmers: Conduct training programs and workshops to educate farmers about pest and disease identification, prevention, and control measures. Promote awareness of sustainable agricultural practices, including IPM techniques, proper pesticide use, and adherence to safety guidelines.
- Consult Agricultural Experts: Seek advice from agricultural extension services, agronomists, or plant pathologists for expert guidance on pest and disease management specific to your region. They can provide up-to-date information, recommend suitable control measures, and assist in decision-making for effective crop protection.
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