Loranthus

Parasitic plant: Scurrula parasitica Crop: Citrus   Why is it a problem? This parasitic plant can reduce growth and vigour of citrus trees. It is easily managed, and only causes serious problems in neglected orchards. Where and when is it a problem?  It occurs in all citrus growing areas from …

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Asiatic citrus psyllid

Diaphorina citri Crop: Citrus Why is it a problem? The Asiatic citrus psyllid (ACP)  is the primary vector of the devastating disease, huanglongbing (HLB). Management of the vector is important to slow the spread of the disease within and between orchards. At high densities direct feeding can also damage plants, …

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Green citrus psyllid

Cacopsylla heterogena Crop: Citrus   Why is it a problem? The green citrus psyllid causes direct damage to new growth of both young and adult citrus trees. This is expected to reduce growth rates and yield. It is not known to vector the HLB pathogen although adults can acquire the …

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Citrus shield bug

Rhynchocoris poseidon Crop: Citrus Why is it a problem? Feeding on sap of young mandarins can cause considerable early (“summer”) fruit drop, although compensatory development of remaining fruit can lessen the economic importance. Damage can be severe, but management is generally not needed in most years and orchards. Where and …

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Citrus leaf miner

Phyllocnistis citrella Crop: Citrus Why is it a problem? The citrus leaf-miner is mainly a problem in young (seedling) trees, including in nurseries, where at high densities it retards growth and can result in secondary infections. Mature trees are better able to withstand the attack. Where and when is it …

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Chinese fruit fly

Bactrocera minax Crop: Citrus Why is it a problem? Chinese fruit fly is the most serious insect pest of citrus. UP to 70% losses through late fruit drop have been reported. It remains difficult to manage. Where and when is it a problem? It is most important in orchards above …

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Citrus trunk borer

Anoplophora nr versteegi Crop: Citrus Why is it a problem? Stem-boring larvae can cause tree decline, mostly by ring-barking of younger trees. Pest populations are slow to build up and are relatively easily managed. Pesticides are not needed. Where and when is it a problem? The beetle is present in …

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Huanglongbing (HLB)

Candidatus Liberibacter asiaticus Crop: Citrus Why is it problem? Huanglongbing (HLB), is one of the most devastating citrus diseases globally. There is no known cure for the disease. It probably entered Bhutan in the 1960s and has become the most serious threat to citrus production. Huanglongbing infection results in reduced …

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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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Citrus

Citrus, mainly mandarin, is almost exclusively grown as a cash crop. It is the most important fruit crop in Bhutan (33,470 MT of mandarins produced in 2013), with most exported (75% in 2013). Citrus is grown in 16 dzongkhags with major areas located in the subtropical southern regions. Fruit from …

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