Lichens on apple

Crop: Apple Why is it a problem? Tree lichens are common in all apple orchards. They are only a problem if allowed to cover branches and young shoots. In severe cases they cause drying of branches and reduce growth and fruiting. This normally only occurs in poorly managed orchards and …

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Premature leaf fall (PLF)

Alternaria mali or Gloeodes pomigena Crop: Apple   Why is it a problem? As the name suggests, premature leaf fall (PLF) disease of apple results in defoliation of parts or entire trees while apples are still developing. On rare occasions, it can also infect apples which become black by harvest …

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Apple scab

Venturia inaequalis Crop: Apple   Why is it a problem? The major economic loss through apple scab is the substantial reduction in fruit quality of scabbed apples. Considerable management, including the use of fungicide, is needed to prevent loss of fruit quality (“improve apple colour”) in susceptible areas. More severe …

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Fruit tree red spotted mite

Panonychus ulmi Crop: Apple Why is it a problem? Prolonged, intense infestations weaken apple trees, seriously affecting the development of shoots, buds and fruit set in the following year. Where and when is it a problem? Mites can be a pest in most apple growing regions, but serious problems are …

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Apple fruit beetles

Popillia species and Protaetia neglecta Crop: Apple Why is it a problem? The adults of six species of apple fruit beetles all feed on developing and developed apples, making them unmarketable. Although feeding damage can be conspicuous, the economic impact is not important unless beetles arrive in large numbers. They …

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Green apple weevil

Myllocerus sp. nr chloris Crops: Apple, peach Why is it a problem? Adults feed in groups on small apples, causing rot and making them unmarketable. They can arrive in large numbers. However, as they normally feed in groups total fruit loss is generally quite low and they can be relatively …

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Two-spotted apple beetle

Microserica sp. Crop: Apple Why is it a problem? Large beetle numbers can defoliate trees. This is mainly a problem with young trees and newly established orchards where it can retard growth. Where and when is it a problem? Problems have been recorded in Thimphu and Paro valley from late …

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Apple twig borer

Linda rubescens Crop: Apple Why is it a problem? Larvae bore into stems causing twig dieback. This is most damaging in seedlings where the main leading shoot can be destroyed. Outbreaks are very easily managed without pesticides, provided trees are monitored. Where and when is it a problem? Outbreaks are …

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Woolly aphid

Eriosoma lanigerum Crop: Apple Why is it a problem? The woolly aphid is a very conspicuous pest on trees of all sizes, but is mostly a problem on small trees on which it can stunt growth. Galls can also cause splitting and secondary infections, and root galls can affect nutrient …

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San Jose scale

Diaspidiotus perniciosus Crop: Apple Why is it a problem? When feeding on apples this scale insect leaves red spots, and in severe cases distorts the fruit. This affects sale prices, especially for export.  Complete coverage on twigs and branches can lead to dieback of affected parts and ultimately the decline …

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