Diseases

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Corn smut

Yield losses due to corn smut may approach 100 %. Smuts appear in the stalks, leaves, tassels or ears. Whitish-gray irregularities which expand and turn black as they fill with spores are observed fir...

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Diseases

  1. Leaf spot can cause yield losses that range from 40-60%. Early leaf spot is seen as reddish-brown spots on the upper surface of leaves surrounded by a yellow halo and brown on the lower leaf surface. Symptoms are first observed on the older leaves. L...

  2. Powdery mildew losses are as a result of losses due to reduced crop yield and quality. Crop yield losses of more than 20 % due to powdery mildew incidences have been recorded. Powdery mildew is observed by powdery splotches of white or gray fungal gr...

  3. Downy mildew is usually prevalent on older onion leaves and stalks. The first evidence of disease is a fine, furry, greyish white to purple growth on the surface of older leaves. Colonies often appear first on the underside of leaves. Small yellow sp...

  4. Common bean mosaic virus causes yield losses due to loss of photosynthetic area. Losses of up to 70% have been recorded in some fields. Common bean mosaic virus symptoms appear as a light green-yellow and dark green mosaic pattern, or they may also a...

  5. Severe yield losses of more than 50% are observed with grey leaf spot. Symptoms of grey leaf spot are usually observed on the lower leaves of the maize plant. Grey leaf spot first appears as small, necrotic spots with chlorotic halos (more visible wh...

  6. Losses due to maize streak virus are usually as a result of loss of photosynthetic area. Yield losses of up to 100% are common with the disease. Maize streak virus develops as small, pale, circular spots or flecks on the youngest leaves (older leaves...

  7. Anthracnose is a disease of economic importance in beans, causing upto to 60% losses. The leaves, petioles, stems, roots pods of bean plants are usually susceptible to infection by anthracnose. Symptoms are usually visible soon after crop emergence a...

  8. Yield losses due to corn smut may approach 100 %. Smuts appear in the stalks, leaves, tassels or ears. Whitish-gray irregularities which expand and turn black as they fill with spores are observed first. Galls on leaves remain small, fleshy and smoot...

  9. Rust can cause yield losses that can go up to 25%. Rusts develop on all parts of the plant but are more numerous on the underside of leaves, stems and pods. Initially, tiny, white, slightly raised spots which will become distinct round reddish-brown ...

  10. Early blight can cause total plant losses if it is not controlled properly. Early blight is observed by brown spots with concentric rings that form a “bull’s eye” pattern usually on lower, older leaves first. These may be observed on the stem as dry,...

  11. Total crop losses are common without proper management of late blight. Late blight first appears as small, grey-green (which darken with time), water-soaked spots (lesions) usually on the underside of the leaf. The spots will enlarge and a white mold...

  12. Severe infection with halo blight can result in total crop loss. Halo blight usually affects the foliage and pods of beans. Leaf symptoms first appear as small, water-soaked spots on the lower leaf surface. These lesions rapidly become necrotic and a...

  13. Rosette virus contributes losses of up to 46 %. Groundnut rosette disease is a combination of three diseases: chlorotic rosette, mosaic rosette and green rosette. Plants with chlorotic rosette have bright yellow leaves, except for small parts that re...

  14. Yield losses of up to 90 % have been recorded in cases with soft rots. Bacterial soft rots first appear as necrotic water-soaked spots on the outside of the fruit (also affects leaves, stems and underground parts). These spots enlarge over time and b...

  15. Blotch is observed on all above ground parts.Symptoms are first observed on the lower leaves as yellow spots. These water-soaked spots (lesions) turn dry, yellow then red-brown. The elliptical lesion enlarges, becomes zonate (target spot) and purplis...

  16. Ergot bodies are produced in place of kernels. The ergot bodies have a hard protective rind on the outside, which is black to dark purple in color, and a white to grey colored interior. They are often elongated and protrude from the glumes of maturin...

  17. Total yield losses can be seen where fields are infested with bacterial wilt. Water melons are known to be immune to bacterial wilt. The first sign of bacterial wilt is wilting of 1-2 leaves (or a part of the plant) on young plants during the day and...

  18. Cankers will cause yield losses that range from 70-80 %. Bacterial canker is observed on each growth stage of the plants’ life. Small, white, raised spots may form on leaves of seedlings. The seedling wilts. Leaves on one side wilt first. The whole p...

  19. Black rot causes damage that results in yield losses of more than 50 %. Bacterial black rot in young plants is observed by dark, discolored cotyledon margins which later drop off. Lower leaves develop lesions which are initially seen by a pale green ...

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