ProMED-mail is a program of the
Source: KSL TV [summ. Mod.DHA, edited]
A virus is wiping out large portions of tomatoes in Utah, impacting crops all over the state. A farmer said it's the worst harvest in 20 years with about 90% of his crop lost to disease. The curly top virus is the suspected cause.
Plants may also have been affected by different root fungi that came as a result of a cool spring, followed by an early summer.
[Byline: Mike Anderson]
[Curly top disease of tomato is caused by _Beet curly top virus_ (BCTV; genus _Curtovirus_, Geminiviridae). The virus has a wide host range and also affects other crops, including beans, capsicum, spinach, sugar beet, cucurbit vegetables, as well as a range of ornamental and weed species. Symptoms may include distortion (curling) and yellowing of leaves, necrosis of phloem tissue, as well as stunting and distortions of roots and plants. The disease reduces plant vigour, yield can be severely affected or plants may die altogether.
BCTV is spread by the beet leafhopper (_Circulifer tenellus_) and can also be transmitted by grafting. The virus overwinters in the vector insects which remain infective for life. The leafhoppers migrate in spring and spread the virus. Weeds and volunteer crop plants may serve as vector and pathogen reservoirs. Disease management is difficult; it may include control of vector insects and reservoir plants by pesticide/herbicide sprays or cultural methods. No genetic resistance has been found in tomato so far and all commercial cultivars are susceptible.
A few other geminivirus species in the same genus and the related genus _Becurtovirus_ (e.g. _Beet curly top Iran virus_; ProMED post 20070712.2228) can cause similar symptoms with similar host ranges.
A large number of fungal pathogens are known to affect all parts of tomato and related solanaceous crops (see link below).
USA (with states):
Curly top symptoms on tomato:
Photo gallery of curly top on other crops via:
Beet leafhopper vector:
Information on curly top disease:
http://cals.arizona.edu/yavapai/anr/hort/byg/archive/curlytopvirus2013.html, http://entoweb.okstate.edu/ddd/diseases/curlytop.htm, and
Virus taxonomy via:
Information on beet leafhopper:
List of major root (and other) fungi of tomato via: