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
Scarlet Crush™
Our new Honeycrisp/Pink Lady® cross is sweet with citrusy notes, plus all that famous Honeycrisp snap and juiciness. Up to to 3” pink/rosy-red fruit is uniform, conical and very attractive. A fine cooking and fresh-eating apple. Keeps up to 6 months. Ripens as early as late September. USPPAF. Best pollinators: Starkspur® Red Rome Beauty, Stark® Jon-A-Red® Jonathan or any Golden Delicious. Zones: 3-6.
Fruits
December 8, 2016
Stark Bro’s Nurseries & Orchards Co. 2017 Variety Showcase [Slideshow]
For more information on these varieties, contact Stark Bro’s Nurseries & Orchards. Stark Bro’s Nurseries & Orchards P.O. Box 398 Read More
Past industry efforts to discover Paradox hybrid seedlings (Juglans hindsii x J. regia) with superior traits have led to advanced selections of Paradox clones, each with unique characteristics. The University of California selection, RX 1, is a top-choice for Sacramento Valley walnut orchardists and others looking for resistance to Phytopthora and good survivability. RX 1 is a cross of Juglans microcarpa x J. regia. It is showing to be one of the most adaptable walnut rootstocks, producing a large tree with the highest yields in replicated trials. USPP#20,649 P3
Fruits
December 7, 2016
Sierra Gold Nursery 2017 Variety Showcase [Slideshow]
Sierra Gold Nurseries in Yuba City, CA, offers two walnut rootstocks, a salt-tolerant pistachio rootstock, and more. Read More
Action shot of an automated strawberry picker from Harvest CROO
Equipment
December 6, 2016
USDA Announces $3 Million For Robotic Agriculture Research
More evidence being found about how people can benefit from automation in the field. Read More
billevans
Apple Grower of the Year
December 6, 2016
2014 Apple Grower Of The Year Bill Evans Dies
Legendary apple grower Bill Evans, who along with his wife, Jeannette, farmed more apple acreage than any grower in the Read More
weedy watermelon field
Crop Protection
December 6, 2016
New Fact Sheet Analyzes Weed Seeds And Their Longevity
Topics covered include how weed seeds travel, when they germinate, and ways they can be eliminated. Read More
Field trials are one component being used to evaluate water and nitrogen use efficiency in lettuce.  A wide array of germplasm is being screened including cultivars of leaf, romaine, iceberg and butter types, mapping populations and non-domesticated primitive types and wild lettuce species.   Photo credit: David Still
Crop Protection
December 6, 2016
Scientists Aim To Improve Nitrogen, Water Use Efficiency In Lettuce
Genetic research intends to develop varieties with enhanced nutrient uptake. Read More
Cannabis plant closeup
Citrus
December 6, 2016
Report: Florida Cannabis Business To Approach $2 Billion By 2020
Lofty projections include a compound annual growth rate of 140%. Read More
Growers participate in a real-time industry survey session at the 2016 Florida Citrus Show
Citrus
December 6, 2016
Florida Citrus Community Tasked To Unify For Stronger Future
A group effort is necessary to forge ahead. Read More
field shot the Produce Peddler Colorado
Crop Protection
December 6, 2016
Orondis Opti Fungicide Receives Registration In Premix Formulation
The product provides control of Oomycete diseases in vegetables and other specialty crops. Read More
BlackPearl® is the best early season cherry, ripening 10 days before Bing and around Chelan. It has exceptional flavor and is extremely firm and crunchy. BlackPearl® is medium size with 20% sugar and keeps better that most other cherries. The tree is hardy and canker resistant. Early season bloom, S4 unknown.
Fruits
December 6, 2016
Fowler Nurseries, Inc. 2017 Variety Showcase [Slideshow]
For more information on these varieties, contact Fowler Nurseries, Inc. Fowler Nurseries, Inc. 525 Fowler Rd. Newcastle, CA 9565827 Phone: Read More
The Latest
Fruits
December 8, 2016
Stark Bro’s Nurseries & Orchards Co.…
For more information on these varieties, contact Stark Bro’s Nurseries & Orchards. Stark Bro’s Nurseries & Orchards P.O. Box 398 Read More
Fruits
December 7, 2016
Sierra Gold Nursery 2017 Variety Showcas…
Sierra Gold Nurseries in Yuba City, CA, offers two walnut rootstocks, a salt-tolerant pistachio rootstock, and more. Read More
Equipment
December 6, 2016
USDA Announces $3 Million For Robotic Ag…
More evidence being found about how people can benefit from automation in the field. Read More
Apple Grower of the Year
December 6, 2016
2014 Apple Grower Of The Year Bill Evans…
Legendary apple grower Bill Evans, who along with his wife, Jeannette, farmed more apple acreage than any grower in the Read More
Crop Protection
December 6, 2016
New Fact Sheet Analyzes Weed Seeds And T…
Topics covered include how weed seeds travel, when they germinate, and ways they can be eliminated. Read More
Crop Protection
December 6, 2016
Scientists Aim To Improve Nitrogen, Wate…
Genetic research intends to develop varieties with enhanced nutrient uptake. Read More
Citrus
December 6, 2016
Report: Florida Cannabis Business To App…
Lofty projections include a compound annual growth rate of 140%. Read More
Citrus
December 6, 2016
Florida Citrus Community Tasked To Unify…
A group effort is necessary to forge ahead. Read More
Crop Protection
December 6, 2016
Orondis Opti Fungicide Receives Registra…
The product provides control of Oomycete diseases in vegetables and other specialty crops. Read More
Fruits
December 6, 2016
Fowler Nurseries, Inc. 2017 Variety Show…
For more information on these varieties, contact Fowler Nurseries, Inc. Fowler Nurseries, Inc. 525 Fowler Rd. Newcastle, CA 9565827 Phone: Read More
Vegetables
December 6, 2016
Rupp Seeds 2016 Vegetable Variety Showca…
For more information, contact, Rupp Seeds: 17919 County Rd. B, Wauseon, OH 43567 800-700-1199; WEBSITE www.RuppSeeds.com FAX 419-337-5491; EMAIL [email protected] Read More
Farm Marketing
December 6, 2016
Registration Is Open For 32nd Annual Nor…
The six-day event for agritourism operators heads to the Northeast with highlights including bus tours, educational sessions and workshops, and business exchange. Read More
Insect & Disease Update
December 5, 2016
Best Practices For Bactericides Key To V…
Approval finally cleared for antimicrobial applications, and now growers wait and hope to see positive results. Read More
Citrus
December 5, 2016
South Florida Endures Driest November On…
Region has not experienced any significant rainfall since Hurricane Matthew. Read More
Fruits
December 5, 2016
Fall Creek Nursery 2017 Variety Showcase…
For information about these varieties, contact Fall Creek Nursery: Fall Creek Nursery 39318 Jasper Lowell Road Lowell, OR 97452 800-538-30015 [email protected] Read More
Fruits
December 5, 2016
Team Coverage: Fruit And Nut Industry Co…
Can’t make it to the biggest fruit and vegetable conferences? No sweat, we’ll take you there. Read More
Vegetables
December 4, 2016
Rispens Seeds 2016 Vegetable Variety Sho…
For more information, contact Rispens Seeds: 1357 Dutch American Way, P.O. Box 310, Beecher, IL 60401 708-946-6560; WEBSITE RispensSeeds.com FAX Read More
GenNext Growers
December 4, 2016
New Loans Available For Small, Beginning…
USDA recently announced streamlined guaranteed Loans and additional lender category for small-scale operators. Read More