Powdery mildew

Oidium citri Crop: Citrus Why is it a problem? This fungus is mostly a problem in nurseries and young orchards where it prevents growth, although new growth in older orchards can also be affected. Severe infections kill branches. It can also attack young fruitlets causing distortion and premature fruit drop. …

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Turcicum leaf blight (TLB)

Exserohilum turcicum Crop: Maize Why is it a problem? This was the most important disease of maize, causing significant yield losses. However, the release of tolerant varieties means that it is now relatively easily managed. Where and when is it a problem?  Turicum leaf blight is most prevalent between 1200 …

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Gray leaf spot (GLS)

Cercospora zeae-maydis Crop: Maize Why is it a problem? First detected in Bhutan in 2006, this disease quickly became the most serious threat to maize production. A major research and development program successfully resulted in the release of GLS tolerant maize varieties. This disease can now be managed relatively easily. …

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Clubroot

Plasmodiophora brassicae Crops: Cole crops Why is it a problem? Clubroot is a disease that deforms the roots of Cole crops preventing and distorting their development and making the plant susceptible to secondary infection. It is difficult to control, and spores can survive many years in the soil. High spore …

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Harlequin bug

Eurydema spp. Crops: Cole crops, beans, spinach Why is it a problem? Harlequin bugs can be damaging during the seedling stage and early stage of the crops in Bhutan. The concentrated attack causes widespread withering of young leaves. However, it rarely causes economic losses. Where and when is it a …

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Cabbage aphid

Brevicoryne brassicae Crops: Cole crops, also mustard and radish Why is it a problem? The wax, shed skins, mold, and honey dew associated with cabbage aphid colonies can spoil the appearance of Cole crops for market. This is primarily a problem for broccoli, where the heads can become unsaleable. Where …

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Diamondback moth

Plutella xylostella Crop: Cole crops Why is it a problem? Diamondback moth (DBM) larvae feed on the foliage of Cole crops. Although larvae are small, outbreaks can destroy entire crops if not recognized and managed in time. Larvae can be evenly distributed across a field, so can cause significant losses …

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Cabbage moth

Mamestra brassicae Crops: Cole crops Why is it a problem? Cabbage moth larvae are large and feed individually. They feed within cabbage heads, and even the presence of a few larvae within a head can completely spoil it for market. Once inside the cabbage, they can be difficult to find …

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Cabbage white butterfly

Pieris brassicae Crops: Cole crops Why is it a problem? The cabbage white butterfly is probably the most important of several moth pests that feed on Cole crops in Bhutan. It is a conspicuous pest that can be managed through regular monitoring and physical control, although insecticides are often used. …

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Angoumois grain moth

Sitotroga cerealella Crop: Stored grain, especially maize Why is it a problem? The grain moth is an important pest of whole cereal grains, especially maize. It destroys the inside of grains, resulting in weight loss. Where and when is it a problem? Grain moths are less widespread than grain weevils. …

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