Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/8/2004
Publication Date: 4/1/2005
Citation: Adkins, S.T., Baker, C.A., Achor, D., Roberts, P.D., Kamenova, I., Muchovej, R.M., Gilreath, P., Mcavoy, G. 2005. Viral involvement in vine decline of watermelon in florida. Meeting Abstract.
Technical Abstract: A severe watermelon vine decline occurred just before or soon after the first harvest in spring 2003 and 2004 in southwest Florida and in fall 2003 in west central Florida. Slight yellowing to scorched and brown leaves, wilting of the vines, defoliation, and rapid mature vine collapse were characteristic symptoms. Frequently, the interior fruit rind appeared greasy and discolored (brown) and fruit were not marketable. Disease progress was very rapid. In some fields, vine decline incidence increased from 10% to greater than 80% within a week. Entire fields were lost. Some growers experienced losses in excess of 50% of their crop. Possible environmental and biological causes of this vine decline were explored including nutrient analyses of soil and plant tissue, grower cultural practices and pathogens. Various fungi and bacteria were recovered from symptomatic crown, root, foliar, and fruit tissue. Several fungal isolates caused watermelon seedling death following inoculation in the laboratory but their role as primary factors or opportunistic secondary factors in vine decline remains under investigation. Watermelons with decline symptoms were also examined for the presence of viruses and virus-like agents. Crude extracts of plant sap from these symptomatic watermelons were filtered to remove fungi and bacteria and used to inoculate greenhouse grown watermelon plants. The inoculated plants developed decline symptoms similar to those observed in the field and died. Other tests indicated the presence of a potyvirus in the declining plants. This potyvirus was identified as Papaya ringspot virus type W (PRSV-W), a pathogen commonly observed in Florida watermelon fields. PRSV-W was purified and used to inoculate additional watermelon plants. However, the purified PRSV-W alone did not lead to the same symptoms of vine decline. This and other evidence suggest the presence of a second virus or virus-like agent that may be involved in vine decline. Research is ongoing to identify this other virus or virus-like agent and determine the role it may play in vine decline.