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
Berries
May 26, 2017
Jury Sides with University in Strawberry Breeding Lawsuit
Decision says former breeders infringed on UC patents to develop material for corporate breeding firm. Read More
Managed bee hive boxes around a blueberry field
Nuts
May 25, 2017
Stolen Hives Recovered in Nearly $1M Heist
Man likely stole hives from across the state of California in the last three years. Read More
Panama Canal Expansion opening celebration
Farm Management
May 25, 2017
Plight of Trade Policy Grounding Many U.S. Growers
Much-needed investments in labor-saving technology could be key to long-term survival. Read More
Cannabis plant closeup
Farm Management
May 25, 2017
Florida Farm Winning Case for Medicinal Cannabis License
Judge rules in favor of 3 Boys Farm in the quest to expand its crop/business portfolio. Read More
hands holding a globe
Citrus
May 25, 2017
Are We Overstating the World’s Overpopulation Problem?
If growers can’t achieve a fair return on investment and stay in business, it won’t matter what the population is in 2050. We all will be trouble. Read More
Falcon-takes-flight-at-Duncan-Family-Farms
Citrus
May 24, 2017
Falcons Scare off Other Birds at Duncan Family Farms
It collaborates with a firm that uses trained falcons to intimidate and scare off nuisance birds such as the horned larks and pigeons that frequent the area. Read More
Organic
May 24, 2017
Organic Growers in Turmoil (Opinion)
Although consumers are demanding, and getting more organic produce options, growers are grappling with fundamental questions. Read More
Corn leaf aphids on sweet corn
Sweet Corn
May 24, 2017
Stay on Your A Game to Conquer Corn Leaf Aphid
Learn how to identify, the survival and spread, as well as management methods for this vegetable pest. Read More
Florida Ag Hall of Famer William Cook
Citrus
May 23, 2017
Search is on For Next Crop of Florida Agriculture Hall of Famers
Nomination period now open for longtime industry honor. Read More
Apples & Pears
May 23, 2017
Grower Shares Personal Impact of Labor Shortage
USApple leader Phil Glaize of Virginia stresses need for reform with current labor regulations, programs at Congressional briefing on agriculture labor crisis. Read More
Stone Fruit
May 23, 2017
Northeast Peach Crop Rebounds
After a mild winter and relatively uneventful bloom time, the crop is setting up nicely for the region. Read More
Berries
May 23, 2017
Researchers Examining Potential for Longer Berry Season in Northeast
Team at Penn State University using low and high tunnels and plastic coverings to extend raspberry and strawberry seasons. Read More
honeybees
Citrus
May 23, 2017
Webinar Series Highlights New Research on Honeybee Health
National Pollinator Week webinar showcases research to improve honeybee colony health by 2020. Read More
stack of lemons
Citrus
May 23, 2017
California Lemon Growers Sue USDA
Lemon industry files suit against rule allowing importation of Argentine lemons. Read More
Bee Vectoring Technologies experimental hives
Citrus
May 23, 2017
Insects (Bad and Good) Make for Interesting Field Trips
Disease-fighting bees and the deadly citrus psyllid were at the center of two recent, research-fueled out-of-office adventures. Read More
The Latest
Berries
May 26, 2017
Jury Sides with University in Strawberry…
Decision says former breeders infringed on UC patents to develop material for corporate breeding firm. Read More
Nuts
May 25, 2017
Stolen Hives Recovered in Nearly $1M Hei…
Man likely stole hives from across the state of California in the last three years. Read More
Farm Management
May 25, 2017
Plight of Trade Policy Grounding Many U.…
Much-needed investments in labor-saving technology could be key to long-term survival. Read More
Farm Management
May 25, 2017
Florida Farm Winning Case for Medicinal …
Judge rules in favor of 3 Boys Farm in the quest to expand its crop/business portfolio. Read More
Citrus
May 25, 2017
Are We Overstating the World’s Ove…
If growers can’t achieve a fair return on investment and stay in business, it won’t matter what the population is in 2050. We all will be trouble. Read More
Citrus
May 24, 2017
Falcons Scare off Other Birds at Duncan …
It collaborates with a firm that uses trained falcons to intimidate and scare off nuisance birds such as the horned larks and pigeons that frequent the area. Read More
Organic
May 24, 2017
Organic Growers in Turmoil (Opinion)
Although consumers are demanding, and getting more organic produce options, growers are grappling with fundamental questions. Read More
Sweet Corn
May 24, 2017
Stay on Your A Game to Conquer Corn Leaf…
Learn how to identify, the survival and spread, as well as management methods for this vegetable pest. Read More
Citrus
May 23, 2017
Search is on For Next Crop of Florida Ag…
Nomination period now open for longtime industry honor. Read More
Apples & Pears
May 23, 2017
Grower Shares Personal Impact of Labor S…
USApple leader Phil Glaize of Virginia stresses need for reform with current labor regulations, programs at Congressional briefing on agriculture labor crisis. Read More
Stone Fruit
May 23, 2017
Northeast Peach Crop Rebounds
After a mild winter and relatively uneventful bloom time, the crop is setting up nicely for the region. Read More
Berries
May 23, 2017
Researchers Examining Potential for Long…
Team at Penn State University using low and high tunnels and plastic coverings to extend raspberry and strawberry seasons. Read More
Citrus
May 23, 2017
Webinar Series Highlights New Research o…
National Pollinator Week webinar showcases research to improve honeybee colony health by 2020. Read More
Citrus
May 23, 2017
California Lemon Growers Sue USDA
Lemon industry files suit against rule allowing importation of Argentine lemons. Read More
Citrus
May 23, 2017
Insects (Bad and Good) Make for Interest…
Disease-fighting bees and the deadly citrus psyllid were at the center of two recent, research-fueled out-of-office adventures. Read More
Crop Protection
May 23, 2017
Valent Grants Organic Farming Scholarshi…
University of Florida Doctor of Plant Medicine student receives $1,500 toward the development of training materials. Read More
Varieties & Rootstocks
May 23, 2017
In Quest for Low-Seeded Citrus, It Takes…
Momentum for viable mandarin hybrids for Florida reaching a peak in the land down under. Read More
GenNext Growers
May 22, 2017
How to Make Dollars and Sense of Today&#…
Despite current challenges impacting the future of the North American fruit and vegetable industry, there are opportunities to be had. Read More