Knowledge Gained

In the early 2000s, a new condition began plaguing watermelon crops in Florida in which fruit rinds would brown on the interior and vines would rapidly collapse and die. The disease was given the name watermelon vine decline (WVD) and was responsible for $60 million in yield losses in 2005.

Back then, little was known about WVD. But soon, scientists discovered the culprit. Scott Adkins, a plant pathologist with USDA’s Horticultural Research Lab in Ft. Pierce, identified an ipomovirus in the family of Potyviridae from an isolate originally collected by Susan Webb, entomologist with the University of Florida, in squash plants that caused the veins of leaves to yellow. Hence, it was called squash vein yellowing virus (SqVYV). Through collaboration with other researchers at USDA-ARS, FDACS, and UF/IFAS, it was confirmed this virus was the cause of WVD. It also has been established WVD is vectored by the sweetpotato whitefly (AKA silverleaf whitefly).
“This is very clearly transmitted by the whitefly, but it is a very different virus in terms of other whitefly viruses we are used to here in Florida like tomato yellow leaf curl virus (TYLCV),” says Adkins. “Over the past four or five years, we’ve been working to nail down some of the biology of the virus and its transmission. There is no silver bullet for WVD, but there are a number of things you can do to help manage the virus. If you do them all, you will be in better shape than you would be otherwise.”

Whitefly Priority

In addition to WVD, two other cucurbit viruses transmitted by the whitefly have been identified in Florida — cucurbit leaf crumple and cucurbit yellow stunting disorder viruses. The combination of all three has placed an emphasis on whitefly management in watermelon and other cucurbit crops.
 
Great care should be taken to avoid the development of whitefly resistance to insecticides. Control actions for the whitefly in cucurbits will be similar for TYLCV in tomatoes, although it is likely control recommendations in cucurbits will evolve over time.

Clean And Weed

Crop hygiene should play a critical role in a grower’s approach in helping keep whitefly numbers low. These practices will help delay the initial whitefly infestation and slow the introduction of viruses into the crop.
– Establish a minimum two-month crop free period during the summer, preferably from mid-June through mid-August or longer.
– Delay planting new fall crops as long as possible and remove spring crops as early as possible to increase the summer crop-free period and avoid carryover of disease and pests.
– Try to eliminate, as much as is practical, any cucurbit weeds (balsam apple, creeping cucumber, smellmellon) that could serve as a source of viruses and whiteflies for the crop.
– Separate fall and winter cucurbit crops in time and space. Do not plant new crops near or adjacent to old, infested crops.
– If the cucurbit crop is to be a double crop, especially following tomatoes, the previous or primary crop should be thoroughly destroyed to reduce the initial whitefly population. Promptly and efficiently destroy all vegetable crops within five days of final harvest to maximally decrease whitefly numbers and sources of plantviruses.
– Destroy crops block-by-block as harvest is completed rather than waiting and destroying the entire field at one time.

Chemical Control

Sweetpotato whitefly can develop resistance to important insecticides quickly. Particular care should be taken with the neonicotinoids because of their important role in crop care. Use soil applications of neonicotinoids at planting for longer season crops, such as watermelon, so there is less chance of affecting bees pollinating the crop.
 
For best control, use a neonicotinoid as a soil drench at transplanting/seeding, preferably in the transplant/establishment water. In order to preserve the neonicotinoid-free period, do not use split applications of soil drenches of neonicotinoid insecticides (i.e., do not apply at transplanting and then again later).
 
If foliar applications of a neonicotinoid insecticide (dinotefuran, acetamiprid, and thiamethoxam are labeled for cucurbits) are used instead of soil drenches at transplanting, foliar applications should be restricted to the period before flowering because of potential toxicity to bees.
 
Information for this article was extracted from the UF/IFAS report “Recommendations For Management Of Whiteflies, Whitefly-Transmitted Viruses, And Insecticide Resistance For Production Of Cucurbit Crops In Florida.” Learn more at www.ifas.ufl.edu.

Leave a Reply

Featured Stories
Apples & PearsThe Story Of Honeycrisp Is One Of Challenges And Success
January 27, 2015
‘Everything’s different’ in this world of 150 million 40-pound box world of apple growing. Read More
BerriesWhy You Should Be Growing Black Raspberries
January 27, 2015
Amazing health benefits for consumers and production and marketing benefits for the grower make this berry a must-consider option for your operation. Read More
Apples & PearsExpanded Market Access For U.S. Grown Apples To China
January 26, 2015
Agreement expected to boost apple exports by $100 million per year. Read More
CitrusNominees Sought For Florida Agricultural Environmental Leadership Award
January 26, 2015
Honor recognizes those developing and adopting environmentally innovative farming practices. Read More
CitrusIncreased Global Trade Opportunity Equals New Threats For Crops [Opinion]
January 26, 2015
Despite expanding business abroad, Florida Agriculture Commissioner Adam Putnam says he's confident in the protocols in place to prevent entry of invasive pests and disease. Read More
GrapesEstimates Vs. Actual: The Cost Of Installing A Vineyard
January 26, 2015
The true costs of developing a vineyard depend on variables such as vine selection, trellising, and labor. Read More
CitrusShopping For UAVs? Here Are 2 To Consider
January 25, 2015
Check out a couple of high-flying options from Altavian. Read More
OrangesScientists Center On Sweet Spot For Processed Oranges
January 24, 2015
Unique approaches and techniques being employed to sustain and squeeze more out of critical research. Read More
BerriesIf You Could Plant Any Type Of Fruit, Consider A Caneberry [Opinion]
January 23, 2015
Raspberries or a blackberries present some berry good options. Read More
The Latest
Apples & PearsThe Story Of Honeycrisp Is One Of Challenges And Succes…
January 27, 2015
‘Everything’s different’ in this world of 150 million 40-pound box world of apple growing. Read More
BerriesWhy You Should Be Growing Black Raspberries
January 27, 2015
Amazing health benefits for consumers and production and marketing benefits for the grower make this berry a must-consider option for your operation. Read More
Apples & PearsThe Dark side Of Honeycrisp
January 27, 2015
Growers say there’s a love-hate relationship with America’s darling apple. Read More
Apples & PearsExpanded Market Access For U.S. Grown Apples To China
January 26, 2015
Agreement expected to boost apple exports by $100 million per year. Read More
CitrusNominees Sought For Florida Agricultural Environmental …
January 26, 2015
Honor recognizes those developing and adopting environmentally innovative farming practices. Read More
CitrusIncreased Global Trade Opportunity Equals New Threats F…
January 26, 2015
Despite expanding business abroad, Florida Agriculture Commissioner Adam Putnam says he's confident in the protocols in place to prevent entry of invasive pests and disease. Read More
GrapesEstimates Vs. Actual: The Cost Of Installing A Vineyard
January 26, 2015
The true costs of developing a vineyard depend on variables such as vine selection, trellising, and labor. Read More
CitrusShopping For UAVs? Here Are 2 To Consider
January 25, 2015
Check out a couple of high-flying options from Altavian. Read More
OrangesScientists Center On Sweet Spot For Processed Oranges
January 24, 2015
Unique approaches and techniques being employed to sustain and squeeze more out of critical research. Read More
BerriesIf You Could Plant Any Type Of Fruit, Consider A Canebe…
January 23, 2015
Raspberries or a blackberries present some berry good options. Read More
NutsNew Nut Industry Equipment
January 23, 2015
These new products are designed to make a nut grower's life easier. Read More
FruitsJiffy Pumped To Introduce New Produce Propagation Syste…
January 23, 2015
PreGro concept to make its debut at Fruit Logistica. Read More
Apples & PearsSurvey: Positive Indicators For Biocontrols In U.S. Hor…
January 22, 2015
Preliminary results of a survey conducted in December 2014 of more than 850 readers across six Meister Media Worldwide titles Read More
CitrusAsian Citrus Psyllid Marches North In California Citrus…
January 22, 2015
Part of one of the richest agricultural areas in the U.S., Fresno County, has been quarantined. Read More
Apples & PearsReal-World Solutions Highlight First Biocontrols 2015 C…
January 22, 2015
Topping the inaugural event's marquee are presentations on “Driving Crop Quality and Productivity Using Biocontrols” by representatives from two of the largest produce growing organizations in the country. Read More
Food SafetyStill Plenty On The Plate Regarding Food Safety Moderni…
January 22, 2015
Almost two years after originally being proposed, four revised rules are still being picked over. Read More
MarketingFlorida Citrus Commission Probes Federal Marketing Orde…
January 21, 2015
Meeting to be scheduled for March to vet possibilities. Read More
Insect ControlExceptional Care Needed When Taking On Common Blossom T…
January 21, 2015
Learn how to identify, the survival and spread, as well as management methods for this insect pest of vegetables. Read More