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
the sunset on a hot day
Citrus
January 18, 2017
NASA, NOAA Concur 2016 Was World’s Warmest Year on Record
For the third time in three years, the bar is raised on surface temperature statistics. Read More
Vegetables
January 18, 2017
Southwest Growers Are Best Prepared for Succession
Almost half of all Southwest operations are grooming its next generation of leadership — an alarmingly low statistic, but one that is the highest in the country, according to American Vegetable Grower magazine's 2017 State of the Vegetable Industry survey. Read More
Vegetables
January 18, 2017
The Midwest Is Nurturing the Next Generation of Operations
It has more young businesses, percentage wise, than other regions: 39% of responding businesses are less than 10 years old. Read More
Vegetables
January 18, 2017
The West Had the Highest Increase in U.S. Vegetable Production in 2016
The West not only has the largest vegetable operations, it also saw the strongest growth in production in the U.S., according to American Vegetable Grower magazine's 2017 State of the Vegetable Industry survey. Read More
Vegetables
January 18, 2017
One in Five Southeast Growers Use H-2A
American Vegetable Grower magazine's 2017 State of the Vegetable Industry survey revealed quite a few qualities about the Southeast that may surprise you, including it being more likely to use H-2A than other regions. Read More
Vegetables
January 18, 2017
The 2016 Drought Is Having a Big Impact on Northeast Growers
The 2017 State of the Vegetable Industry gave us insight into each region of the U.S. Sifting through the data, we flagged those responses that were markedly higher or lower than other regions. Responses from Northeast growers made it clear that the 2016 drought had taken a toll. Read More
GenNext Growers
January 18, 2017
$858,000 in Grants to Encourage Careers in Agriculture Science
Funding to invest in programs that educate, promote science in the classroom. Read More
Vegetables
January 18, 2017
Mississippi Greenhouse Tomato Short Course Registration Is Now Open
Online registration is now open for the Greenhouse Tomato Short Course, which takes place March 7-8 in Raymond, MS. This Read More
Fruits
January 18, 2017
Spotted Wing Drosophila Control the Topic of Webinar
Research updates, recommendations to be presented on devastating pest. Read More
'Gold nugget' seedless tangerine
Varieties & Rootstocks
January 18, 2017
5 Florida Citrus Nursery Trends Worth Watching
Gleanings from recent grower gatherings expose opportunities and possibilities in new variety development and management. Read More
The Latest
Citrus
January 18, 2017
NASA, NOAA Concur 2016 Was World’s Warme…
For the third time in three years, the bar is raised on surface temperature statistics. Read More
Vegetables
January 18, 2017
Southwest Growers Are Best Prepared for …
Almost half of all Southwest operations are grooming its next generation of leadership — an alarmingly low statistic, but one that is the highest in the country, according to American Vegetable Grower magazine's 2017 State of the Vegetable Industry survey. Read More
Vegetables
January 18, 2017
The Midwest Is Nurturing the Next Genera…
It has more young businesses, percentage wise, than other regions: 39% of responding businesses are less than 10 years old. Read More
Vegetables
January 18, 2017
The West Had the Highest Increase in U.S…
The West not only has the largest vegetable operations, it also saw the strongest growth in production in the U.S., according to American Vegetable Grower magazine's 2017 State of the Vegetable Industry survey. Read More
Vegetables
January 18, 2017
One in Five Southeast Growers Use H-2A
American Vegetable Grower magazine's 2017 State of the Vegetable Industry survey revealed quite a few qualities about the Southeast that may surprise you, including it being more likely to use H-2A than other regions. Read More
Vegetables
January 18, 2017
The 2016 Drought Is Having a Big Impact …
The 2017 State of the Vegetable Industry gave us insight into each region of the U.S. Sifting through the data, we flagged those responses that were markedly higher or lower than other regions. Responses from Northeast growers made it clear that the 2016 drought had taken a toll. Read More
GenNext Growers
January 18, 2017
$858,000 in Grants to Encourage Careers …
Funding to invest in programs that educate, promote science in the classroom. Read More
Vegetables
January 18, 2017
Mississippi Greenhouse Tomato Short Cour…
Online registration is now open for the Greenhouse Tomato Short Course, which takes place March 7-8 in Raymond, MS. This Read More
Fruits
January 18, 2017
Spotted Wing Drosophila Control the Topi…
Research updates, recommendations to be presented on devastating pest. Read More
Varieties & Rootstocks
January 18, 2017
5 Florida Citrus Nursery Trends Worth Wa…
Gleanings from recent grower gatherings expose opportunities and possibilities in new variety development and management. Read More
GenNext Growers
January 17, 2017
9 Financial Resolutions to Boost Your Fa…
If a goal for the new year includes increasing profitability, there are ways you can better manage your business. Read More
Farm Management
January 17, 2017
Will Big Data Yield Big Returns for Farm…
Modern tools of hort tech are ripe to inspire the next generation of productivity and profitability. Read More
Citrus
January 17, 2017
The Future of Agriculture is in Your Han…
Can farmers actually reach the point of having too much information? Read More
Equipment
January 17, 2017
Agricultural Robots No Longer Science Fi…
New automated technologies could help specialty crop growers deal with labor crisis. Read More
Citrus
January 16, 2017
First Bee in Continental U.S. Listed as …
Rusty patched bumble bee receives protection from activities that could cause it to go extinct. Read More
Fruits
January 16, 2017
Pollination Experts Host Webinar Series
Fruit and vegetable growers can prepare for spring by hearing about recent pollination research. Read More
Citrus
January 16, 2017
Precision Agriculture and Big Data Gaini…
Specialty crop adoption of hort tech to usher in new efficiencies and transparency. Read More
Crop Protection
January 16, 2017
Monsanto, NRGene Enter Agreement for Big…
Technology platform is designed to help Monsanto analyze, store, and mine its genomic data sets to enhance breeding and R&D opportunities. Read More