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Whitefly Research Management

Sep 20, 2019 | Written by
Published on 09/13/19

UGA CAES part of extensive research study aimed at whitefly management

By Clint Thompson for CAES News

Researchers from three research institutions are using a $3.2 million grant from the U.S. Department of Agriculture to fight whiteflies on vegetable crops.

Scientists from the University of Georgia College of Agricultural and Environmental Sciences (CAES), Fort Valley State University and the U.S. Department of Agriculture Agricultural Research Service (USDA-ARS) in Charleston, S.C., will combine their expertise to collaborate on finding short- and long-term solutions to fight the pest.

UGA’s team plans to use an integrated approach to solve Georgia’s whitefly problem in vegetables.

“We have seen significant buildup in the last two to three weeks, mostly in the Tift County and Colquitt County region, but I have had reports of isolated problems outside of the area as well,” said UGA vegetable entomologist Stormy Sparks. “The scientists that are part of this grant are studying all aspects of whitefly biology and management to try to find weaknesses that can be exploited for management.”

Sparks is one of the researchers on the UGA team, which includes entomologists, plant pathologists, virologists, breeders and vegetable specialists.

The scientists will rely on one another’s specialties for the duration of the five-year grant.

“My role involves finding resistance to the whitefly-transmitted virus complex in snap bean germplasm, advancing breeding lines and conducting research to find the genetic basis of resistance,” said Bhabesh Dutta, a UGA Cooperative Extension plant pathologist on the Tifton campus and member of the research team. “We’ll then give that information to the breeder so that they can introgress resistance into elite varieties.”

Whiteflies are responsible for transmitting multiple viruses, including cucurbit leaf crumple virus and cucurbit yellow stunting disorder virus. According to UGA crop loss estimates for fall 2017, these viruses caused between 30% and 50% crop loss in squash and cucumbers and nearly 80% crop loss in snap beans that year.

“This project gives us an opportunity to think long term. It’s not going to be a quick fix. We’ll take baby steps to understand the system, understand the problem, and then try to solve it,” Dutta said.

UGA entomologist Babu Srinivasan will focus on studying virus transmission by whiteflies and management.

“We’re trying to look at how these viruses interact with their host, how they interact with their vectors, and how they’re transmitted,” said Srinivasan, who’s based on the UGA Griffin campus. “Once we understand that, it will help us get closer to management.”

The severity, distribution and timing of whiteflies vary from year to year, but they remain a persistent problem for Georgia’s vegetable growers. They are especially problematic in the Tift and Colquitt County region where vegetables are produced year-round.

“It was a devastating event for us in 2017 and we certainly don’t need that again,” said Bill Brim, co-owner of Lewis Taylor Farms in Tifton, Georgia. “We need the university to work real hard on it and, hopefully, we’ll get some more funding next year for it as well.”

Whiteflies built up significant populations as early as May 2017. A warm winter that season did not help diminish the whitefly population. The pest normally becomes a problem in August or September, but the earlier they occur, the worse they become, according to Sparks.

“We cannot successfully manage this pest as simply a pest of fall vegetables. We have to look at the entire cycle and realize that what happens in one area impacts the others,” Sparks said. “Because this pest attacks so many different crops across the agro-ecosystem and cycles from crop to crop throughout the year, we have to understand how it survives and builds in our environment to determine the best strategies for control.”

Where and how whiteflies overwinter leads to populations in spring vegetables. This can have an effect on summer crops, which then impacts fall vegetables.

Following the 2017 epidemic, UGA formed a whitefly team on the Tifton campus. Those researchers are included in this grant project, along with researchers in Griffin, Athens, Fort Valley and Charleston.

“We might be able to fix the problem today, but how do we make sure it’s fixed to where it lasts through next year and the year after — and something even more permanent?” asked Allen Moore, UGA associate dean for research and principal investigator for the grant. “With sufficient resources that the federal government is providing, we ought to be able to do all of that. Rather than take 10 years to come up with something, we’re doing it a lot faster because we’re doing it all at once.”

The grant designates $560,000 to Fort Valley State University with the remaining money divided among the researchers at CAES and UDSA-ARS in Charleston.

Listed are the participating scientists and the areas of whitefly research in which they are involved:

Plant resistant traits: Babu Srinivasan (UGA), Bhabesh Dutta (UGA), Andre da Silva (UGA), Cecilia McGregor (UGA) and Somashekhar Punnuri (Fort Valley State).

Ecology, biocontrol, cultural practice: Phillip Roberts (UGA), Alton Sparks (UGA), Andre de Silva (UGA), Paul Severns (UGA), Jason Schmidt (UGA), Mike Toews (UGA), George Mbata (Fort Valley State) and Alvin Simmons (ARS).

Viruses/transmission dynamics: Babu Srinivasan (UGA), Sadeep Bag (UGA), Paul Severns (UGA), Somashekhar Punnuri (Fort Valley State) and Alvin Simmons (ARS).

Molecular tools/biotech: Trish Moore (UGA), Bhabesh Dutta (UGA), Cecilia McGregor (UGA), Somashekhar Punnuri (Fort Valley State), George Mbata (Fort Valley State) and Alvin Simmons (ARS).

Insecticide resistance/biorational control products: David Riley (UGA), Jason Schmidt (UGA), Alton Sparks (UGA), Phillip Roberts (UGA), George Mbata (Fort Valley State) and Alvin Simmons (ARS).

Clint Thompson is a news editor with the University of Georgia College of Agricultural and Environmental Sciences based in Tifton.

Sunscalding on Fruits and Vegetables

Jun 25, 2019 | Written by
Published on 06/14/19

High temperatures, few clouds lead to sunscalding concerns for Georgia producers

By Clint Thompson for CAES News

Even with the welcomed rain Georgia farmers experienced this week, sunscalding on certain fruits and vegetables remains a concern as producers continue with this year’s harvest, according to University of Georgia Cooperative Extension vegetable specialist Andre da Silva.

When temperatures are high and the sun is able to shine for weeks at a time with very little cloud cover, which had been the case in mid-to-late May, certain crops are vulnerable to developing sunburnt conditions — notably watermelons, tomatoes and bell peppers.

“The sun has definitely been too aggressive for some of our vegetable crops, especially with bell pepper, tomato, and watermelon. Growers have been asking for products to protect their crop from the sun,” da Silva said. “Unfortunately, there is not much research on this topic for us to make a recommendation. However, the first UGA research trial is being conducted this season.”

Watermelons are most susceptible to sun damage if they endure a prolonged dry period. Without moisture, the vines will begin to wilt and the fruit will be more exposed to the sun. When watermelons burn, the rind will appear yellow, rendering the crop unmarketable.

“Growers that need to exercise the most precaution are the watermelon growers who are using plastic mulch with overhead water application. If they haven’t been applying enough water, they will see their plants shrink. It’s hard for the root systems of those plants to get the water that the growers are applying,” da Silva said.

If watermelon producers can protect their crop from the sun, they’ll extend their harvest window into late June and around July 4 when watermelons are at peak demand and prices for farmers are at their best.

“We don’t expect temperatures to get this hot, this early,” da Silva said. “We need a little bit of rain every day with a little bit more clouds to avoid future sunburning, and then we’ll have good soil moisture.”

Prior to the June 8 weekend, the last substantial rainfall in south Georgia was during the weekend of May 11. According to the United States Drought Monitor, (www.droughtmonitor.unl.edu) drought conditions are considered moderate, though da Silva believes they’re still likely much worse. Along with fellow UGA vegetable scientists Bhabesh Dutta and Stormy Sparks, da Silva has traveled across south Georgia to survey the damage inflicted by the weekslong drought.

“If growers hadn’t been pumping up their irrigation this spring, they could very easily lose their crop this year,” da Silva said.

Direct contact of fruit to sunlight can cause blossom end rot disorders. Previous research trials from da Silva and colleague Tim Coolong on the UGA Tifton campus showed that fertilizer strategy, mainly those consisting of calcium nitrate, is key to reducing blossom end rot, a calcium-related disorder that affects mostly peppers and tomatoes.

For up to date information about weather events in Georgia, see the UGA Weather Network website at www.georgiaweather.net.

Clint Thompson is a news editor with the University of Georgia College of Agricultural and Environmental Sciences based in Tifton.

App Helps Fruit Growers

Jun 25, 2019 | Written by
Published on 06/18/19

App helps fruit growers in Eastern U.S. diagnose disease and insect problems

By Denise M Hatcher for CAES News

Walking through his peach orchard, a farmer notices something he has not seen before on the leaves of a few trees. He quickly pulls out his cell phone and accesses the MyIPM smartphone app.

Through a series of descriptions, audio and images, the free mobile app and tool can help users diagnose crop diseases, insect pests and disorders of fruit crops grown in the Eastern U.S., including apple, blackberry, blueberry, bunch grape, cherry, cranberry, peach, pear and strawberry.

The app was first developed by plant pathologists at Clemson University to give growers a “one-stop shop” to access all of the resources they might need for disease management, says Brett Blaauw, an assistant professor and peach specialist with the University of Georgia Department of Entomology. A couple of years later, two more apps were created: one focused on insect pests and another geared specifically for the Northeastern region of the U.S.

“When I came to UGA, I worked on merging the three separate apps into one master app, which included new tools, crops and functionality,” Blaauw said. “The single MyIPM app currently has nine crops with disease diagnostic tools and six crops for insect diagnostic tools.”

To date, the app has been downloaded more than 2,100 times. Designed to promote integrated pest management in commercial fruit crop production, one of Blaauw’s favorite aspects of the app is that it’s full of useful information for users of both Apple iOS and Android mobile operating systems.

“Not only is there a large list of chemistries that are labeled for each disease or insect pest, but users also have the ability to view high-resolution pictures to identify symptoms and signs of disease and insect injury,” he said. “With that said, my real favorite aspect is that the app is free.”

The app is continually being updated by leading Extension specialists at seven land-grant universities and the Southern IPM Center.

Feedback from users has been overwhelmingly positive. Of the users surveyed, 65% say that the app has helped them manage pests and 70% say that it has increased their knowledge of pests and IPM, according to Blaauw.

“Nearly everyone I talk to about the app is pleased with its functionality and ease of use,” he said.

The app has been downloaded to more than 70 different countries, including India, Mexico and Canada.

Blaauw is currently working on adding a section on beneficial insects to help growers identify “good bugs” using the app. He hopes to see the app expanded to include more crops.

For more information on the MyIPM app, visit https://apps.bugwood.org/apps/myipmseries/.

Michele Hatcher is the editor of the Hexapod Herald, the newsletter of the University of Georgia Department of Entomology.

Downy Mildew Disease

Jun 13, 2019 | Written by
Published on 06/04/19

Georgia vegetable growers need to apply fungicides to stay ahead of downy mildew disease.

By Clint Thompson for CAES News

Georgia vegetable farmers should be on alert as downy mildew disease has been spotted in at least three southern Georgia counties this spring. Additional counties could follow as weather conditions remain favorable for the disease into early June, according to University of Georgia Cooperative Extension plant pathologist Bhabesh Dutta.

Cucurbit crops — like cucumbers, melons, squashes and pumpkins — are susceptible to the disease. Dutta ranks downy mildew among the top diseases in cucurbit crops, along with Fusarium wilt and Phytophthora fruit rot.

Downy mildew disease can destroy plant foliage and cause the leaves to curl and die. Without healthy leaves and vines, a plant is vulnerable to blisters and sunscald during hot days, conditions most of Georgia has experienced since early May.

Much of the state has not experienced a substantial rainfall event since the weekend of May 11, and many growers have had no relief from temperatures that reached or eclipsed 100 degrees Fahrenheit.

“We really need some balanced days, not full-blown sunshine with 100 degrees Fahrenheit every day like we’ve experienced here recently, and also not heavy dew nights,” Dutta said. “We need some cloudy days, but most importantly, we need some rain.”

High temperatures during the day, followed by dew at night and in the early morning hours for the past three weeks, have led to the disease developing in cucurbit fields in Crisp, Decatur and Lowndes counties.

“Most of our growers are doing preventative sprays for downy mildew. We do have fairly effective fungicides that can manage downy mildew. I think growers are diligently following UGA recommendations and they should continue to do so,” Dutta said.

Growers need to be aware of what downy mildew symptoms look like and the damage it can inflict on vegetable crops. The pathogen thrives in wet, humid conditions and needs moisture on the surface of the plant for successful spore germination and further infection.

The pathogen that causes downy mildew can’t survive a hard frost, so it overwinters in frost-free regions like southern Florida. During May and early June, wind currents blow the spores into Georgia.

For up-to-date information about potential diseases impacting Georgia’s vegetable production, see https://site.caes.uga.edu/vegpath.

Clint Thompson is a news editor with the University of Georgia College of Agricultural and Environmental Sciences based in Tifton.

Root-Knot Nematodes

May 30, 2019 | Written by
Published on 05/27/19

UGA survey finds root-knot nematodes in 60% of vegetable fields

By Bryce Ethridge for CAES News

A recent University of Georgia Cooperative Extension survey of 431 Georgia vegetable fields found that more than 60% contained root-knot nematodes, tiny parasitic worms that feed on roots and destroy plants.

The survey was conducted May through December of 2018 by UGA Extension nematologist Abolfazl Hajihassani. His research group surveyed fields in 30 Georgia counties for plant-parasitic nematodes and found 10 genera of nematodes. Root-knot nematodes are the most important nematodes that vegetables producers should be concerned with, he said.

Hajihassani conducted the survey to better understand the incidence, abundance and spread of plant-parasitic nematodes within vegetable fields in southern Georgia. The counties surveyed represent about 85-90% of the state’s vegetable production.

During the survey, soil samples were collected from vegetable fields and nematodes were extracted and identified to the genus level.

“Right now, the root-knot nematode is the main problem in most vegetable crops grown here, based on distribution, soil population density and incidence,” he said. “Therefore, root-knot nematodes will be the target of our future research, which will include the evaluation of old and newly introduced fumigant and nonfumigant nematicides.”

Root-knot nematodes can enter the plant’s roots and move through the cells where they grow, produce more eggs in only three to four weeks and cause the roots to swell. This reduces the plant’s growth and yield potential.

South Georgia’s sandy soils allow nematodes to reproduce frequently because they can move easily through the soil’s loose texture.

UGA Extension’s observations in the field indicated that fumigating the soil before applying plastic will stop the nematodes for the season, but only for that season.

Hajihassani said that there are a few nematode-resistant vegetable varieties available, but Georgia producers don’t want to use them because of quality issues. Growers prefer to plant high-yielding varieties and use chemical nematicides, although they’re not always 100% effective.

Currently, Hajihassani is researching the nine other types of nematodes the survey identified in case they could become threats to vegetable production in Georgia. This includes stubby root, ring, spiral, root lesion, reniform, lance, cyst, stunt, and dagger nematodes.

“Hopefully, in one to two years, we’ll have a good source of information as to what species of nematode we have,” he said. “Through Extension agents, we have already communicated the survey data with those growers who participated in our survey. Our aim is to continue sharing the data with growers, find out what problems they have and design the appropriate management techniques.”

Nematodes need three components to thrive: water, high temperatures and a suitable host. Georgia has water, hot summers and a variety of host plants, which has Georgia farmers concerned. Along with vegetables, nematodes can cause problems in cotton, peanut and tobacco plants.

For more information on Hajihassani’s work and plant-parasitic nematodes, visit https://t.uga.edu/4YK.

Cabbage Crops Signs of Disease

May 16, 2019 | Written by
Published on 05/08/19

Farmers must watch cabbage crops closely for signs of disease

By Bryce Ethridge for CAES News

As temperatures increase this spring, Georgia cabbage farmers should scout their crops regularly to ensure that disease pressure is not too high, says University of Georgia Cooperative Extension vegetable specialist Andre da Silva.

If farmers are proactive and maintain proper pest management programs during the growing season, diseases like black rot and Alternaria leaf blight can be controlled, da Silva added.

Symptoms of these disease are easy to identify in the field, but once identified, yield may have already been compromised. The increase in temperatures and rainfall can create perfect conditions for disease, and da Silva and Bhabesh Dutta, UGA Extension vegetable disease specialist, are currently tracking the emergence of the two diseases throughout south Georgia.

“As we get to the summer — or later in the spring — the warmer temperatures increase the chance of these diseases,” he said. “If growers don’t pay attention and keep a proper pest management program, we might suffer a high loss.”

According to the UGA Center for Agribusiness and Economic Development, the farm gate value for cabbage in Georgia in 2017 was $53.6 million.

Alternaria leaf blight can cause spots on some brassica crops and render them unmarketable. Symptoms first appear on older leaves as small, dark spots that gradually enlarge with concentric rings. As the disease gets worse, younger leaves become infected. Infection becomes more problematic in humid and wet conditions.

Black rot causes v-shaped lesions on leaf edges which can lead to the plant’s death.

Lack of proper irrigation scheduling could also lead to the appearance of these diseases, particularly due to the application of high volumes of water.

“Since we’re starting to have warmer conditions with frequent rain showers, soil might have plenty of moisture to supply crop demand,” da Silva said. “There is no need to overirrigate, and if growers are irrigating their cabbage in those conditions, it’d create the perfect conditions for disease. That’s what we don’t want.”

As part of his research on the UGA Tifton campus, da Silva is looking for cabbage varieties that are more disease tolerant or disease resistant.

Until disease-resistant varieties are discovered, growers should keep these tips in mind when managing diseases in cabbage:

  • Maintain a proper pest management program.
  • Rotate chemical products to avoid disease resistance to a particular product.
  • Change up irrigation schedules to apply water only when necessary.
  • Frequently survey crops for symptoms.

To learn how to identify rot, contact da Silva at 229386-3806 or adasilva@uga.edu. For more information on the Department of Horticulture at UGA-Tifton, visit https://tifton.caes.uga.edu/departments/horticulture.htm

Choosing Tomato Varieties (4-H Tomato Sale Going on Now)

Mar 14, 2019 | Written by

By Jake Price

The desire for fresh homegrown tomatoes is probably the main reason homeowners have gardens.  Most plants are planted in late March and April, or when they are available at the garden centers.  Each spring, many homeowners run into problems with their plants.

Two newer, good tasting, disease resistant varieties are currently being sold by the Lowndes 4-H club to support the camping program.   The two varieties are Red Bounty and Bella Rosa which both have resistance to Tomato Spotted Wilt Virus. Call 333-5185 for more information.  Plants are $1.00 each while supplies last.

Tomatoes are susceptible to a lot of diseases.  Once infected, it is too late to stop most diseases from killing or limiting the production of the plant.   Tomatoes come in all shapes, colors, and sizes.   A few cultural practices and planting varieties that are resistant to disease can make for a more productive tomato harvest.

When selecting your plants look for varieties that have a lot of letters next to the name.  This means that plants have a built in resistance to disease.   An example would be a popular variety called Celebrity VFFNTA Hybrid.  The letters stand for the following:

V = Verticillium Wilt
F = Fusarium Wilt
FF = Fusarium Wilt race 1 and 2
N = Nematode
T = Tobacco Mosaic Virus
A = Alternaria (Early Blight)
TSWV = Tomato Spotted Wilt

Tomatoes are classified as determinate which means most of the fruit ripens over a short period of time, and indeterminant, which means that fruit will continually be produced.  Determinant varieties produce a lot of tomatoes early and once the tomatoes have been harvested the plants can be removed.                                                                                                   Popular determinant varieties include:  Bush Celebrity VFFNTA Hybrid, Bush Early Girl VFFNT Hybrid, Celebrity VFFNTA Hybrid, and Mountain Spring VFF Hybrid.  Popular indeterminant varieties are:  Early Girl VFF Hybrid, Better Boy VFN Hybrid, Big Boy Hybrid, and Beefmaster VFN Hybrid.

Cherry tomato varieties are: Jolly Hybrid, Sweet Baby Girl Hybrid, and Super Sweet 100 Hybrid.  Of course there are many more to choose from.  Cultural practices will also prevent problems.

Tomatoes like a well-drained high organic matter soil and a pH between 6.2 and 6.8.  I would recommend you have a soil test done for your garden and follow any recommendations.  A soil test can correct any pH problems.                                                                                 Tomatoes frequently have a problem with a condition called “Blossom End Rot”.  This is when the bottom of the tomato turns black.  Blossom end rot is caused by a calcium deficiency in the fruit and is made worse when soil conditions fluctuate between wet and dry.                                                                                                                                                       Additions of dolomitic lime, which raises pH and contains calcium and Magnesium, can help prevent the problem.   If your soil pH is optimal, but your calcium is low, apply gypsum at 1 pound per 100 square feet.  Foliar applications of calcium can help provide a temporary fix if the problem is not excessive.                                           Mulching around your tomato plants reduces soil moisture fluctuations and keeps the weed pressure down.  Layers of newspaper can be placed around plants and mulch can be added on top to further prevent weeds.  Pine straw, bark, leaves, or most any type of mulch will be ok.

Selecting disease resistant varieties, mulching, and following your soil test results should make your tomato season more productive.  For more information on tomatoes and varieties visit this website:  https://secure.caes.uga.edu/extension/publications/files/pdf/B%201271_5.PDF

Fungicide resistance spells trouble for Georgia, Virginia vegetable farmers

Mar 8, 2019 | Written by
Published on 03/06/19
By Clint Thompson for CAES News

Popular vegetables like broccoli and kale are among the crops that could be in danger from Alternaria leaf blight — a disease that can cause spots on some brassica crops and render them unmarketable — which has developed resistance to a once-dependable fungicide that Georgia farmers rely on, according to Bhabesh Dutta, University of Georgia Cooperative Extension plant pathologist.

Dutta recommends producers stop using Quadris on brassica crops, which include cabbage, collards, kale, mustard greens and broccoli. The fungicide is the main one farmers currently use when treating for the disease. Although further research is required to confirm his hypothesis, Dutta believes a new species of Alternaria may be responsible for the outbreak of disease. The species normally associated with Alternaria leaf blight differs from the disease that has recently been observed in Georgia’s brassica fields.

Tift County, Georgia, vegetable farmer Bill Brim is among the brassica farmers concerned about the development.

“Alternaria has become resistant to Quadris, so it’s not as good as it once was,” said Brim, co-owner of Lewis Taylor Farms in Tifton, Georgia, which includes about 1,500 acres of brassica crops. “We’ve got a little bit left in our arsenal to use for Alternaria. We just need to get something back in there we can use.”

Dutta is conducting a research trial evaluating different varieties of Alternaria leaf blight, along with different fungicide programs against this disease, at the Blackshank Farm on the UGA Tifton campus.

Dutta, an assistant professor of plant pathology in UGA’s College of Agricultural and Environmental Sciences, emphasizes the need to develop an integrated pest management (IPM) program to fight Alternaria leaf blight, especially in broccoli and leafy brassicas.

“We do have some other groups of fungicides that we’ll need to rotate, but considering how effective Quadris has been for our vegetable farmers, this resistance is a huge hit on our growers,” Dutta said.

Alternaria leaf blight first became a problem in Georgia in 2016, but has gotten significantly worse over the past two years.

“Alternaria is a foliar pathogen. Symptoms first appear on older leaves as small, dark spots that gradually enlarge with concentric rings. As the disease progresses, younger leaves can also become infected. In severe cases, infection can occur that results in rot on heads. Infection is exacerbated by humidity and extended periods of leaf wetness from overhead irrigation or frequent rainfall,” Dutta said.

Farmers can employ alternative methods to help prevent the disease from becoming more widespread in their fields. Since the pathogen can survive in crop debris, Dutta recommends farmers bury their crop debris when their spring and fall crops are harvested.

Because the disease propagates and spreads through overhead irrigation, growers should use drip irrigation or a form of subsurface irrigation to help reduce the splashing effect of the pathogen, Dutta said.

Excessive rainfall Georgia in January and February led to outbreaks of the disease this year.

“We have to try to manage this issue with good resistance-management techniques, such as rotating different modes of action in order to preserve the chemistries that we have,” said Jeremy Kichler, Colquitt County Extension coordinator. “Hopefully, if we implement good resistance-management strategies, then we can effectively manage this disease.”

According to the UGA Center for Agribusiness and Economic Development, cabbage production in Colquitt County accounted for more than $42 million in farm gate value in 2017. Colquitt County, which produces approximately 6,500 acres of cabbage in the fall and spring, has experienced severe disease outbreaks.

The production of brassica crops is a profitable industry for Georgia farmers. According to the UGA Center for Agribusiness and Economic Development, the state farm gate value for cabbage was $53.6 million in 2017.

Georgia is not the only state experiencing problems with Alternaria leaf blight. As early as 2015, broccoli growers in Virginia’s Northern Neck region reported severe Alternaria head rot in fields where Quadris was the primary fungicide used. During 2015 and 2016, some growers experienced complete crop failures from this pathogen.

Virginia Tech researchers led by Steve Rideout, director and vegetable plant pathologist at Virginia Tech’s Eastern Shore Agricultural Research and Extension Center in Painter, Virginia, have determined isolates of Alternaria that possess resistance to Quadris.

To learn more about vegetable production in Georgia, see https://extension.uga.edu/topic-areas/lawn-garden-landscapes/fruits-vegetables.html.

Hurricane Harvest Decisions

Oct 9, 2018 | Written by
Published on 10/09/18

UGA Extension advises harvest decisions amidst looming hurricane

By Laurel L Dunn, Andre Luiz Biscaia Ribeiro da Silva for CAES News

Hurricanes, tropical storms and severe rainfall events are commonly seen among states in the Southeast U.S. These natural events most often occur during summer or early fall and may cause severe problems for urban and agricultural areas of Georgia. As of this week, it appears that we have another hurricane poised to strike Georgia. University of Georgia Cooperative Extension wants all of its agents — and the fruit, vegetable and nut growers they serve — to be as prepared as possible for the effects of the storm.

Agricultural areas, particularly where vegetables are grown, are severely impacted by flooding events that result from heavy precipitation. When the edible portion of a crop is contacted by flood waters, the Food and Drug Administration (FDA) deems it “adulterated,” and the crop cannot be used as human or animal food. For this reason, the recommendation is to harvest vegetables and other edible products in advance of the rain, no matter the yield. As long as the total harvest costs are less than the delivered-in value of the produce at the processing plant or the packinghouse, harvesting is still profitable. In sum, harvesting decisions rest on determining an economic threshold for the grower.

Flooding is defined by the FDA as “the flowing or overflowing of a field with water outside a grower’s control.” Since chemical as well as microbial contamination is present in flood waters, there is no way to process fruits and vegetables that are contacted to make them safe again for consumption. If the crop field is flooded, but the water level is not high enough to touch the edible portion, a risk assessment may determine whether the product is likely contaminated or may be harvested. This includes crops that are still standing after the flood (e.g., tomato, bell pepper or eggplant) where the fruit is above the water level and too high for flood water to splash onto the product. Additionally, if the edible portion of the crop has not developed yet, the crop may be safe for future harvest.

UGA Extension specialists prepared a quick guide for Extension agents and growers to properly handle Hurricane Michael as it approaches:

Before an anticipated flood event:

  • Take inventory of and secure any chemicals and hazardous chemicals (e.g., herbicides, insecticides and fungicides).
  • Move any livestock, equipment or tools to elevated areas, preferably areas with no risk of flooding.
  • Use sand bags, berms or ditches and crosscuts to divert water around greenhouses, packinghouses, barns and produce fields.
  • Make copies of important documents and ensure that documents are stored in a secure, waterproof location, or take them with you in the event of evacuation.

 

After a flood event:

  • Contact your insurance agency before any clean-up activities, including salvaging crop fields where a portion of the produce was not contacted by flood water.
  • Clearly identify the highest point of flood water to make sure that contaminated product is not unintentionally mixed with “clean” product.
  • Harvest “clean” produce prior to handling nonharvestable produce to avoid cross-contamination of your produce.
  • If well heads were submerged, do not wash any harvested produce to avoid contamination. Test the water before any use.
  • Boil all water for personal consumption until test results indicate that no detectable generic Escherichia coli are present.
  • Take pictures of all damage immediately in order to send evidence to insurance agencies.
  • Allow a 60-day interval between flooding and replanting of previously flooded fields to allow for human pathogens to die off. Chemical hazards may still be present in previously flooded soils, so chemical and microbial soil testing should be considered prior to replanting.
  • Contact your UGA Extension agent if you are unsure whether produce can be safely harvested.

 

Remember, the more severe the rain, the higher the chance of contamination. For more information, see www.fda.gov and https://producesafetyalliance.cornell.edu

By Laurel L Dunn, Andre Luiz Biscaia Ribeiro da Silva for CAES News

Hurricanes, tropical storms and severe rainfall events are commonly seen among states in the Southeast U.S. These natural events most often occur during summer or early fall and may cause severe problems for urban and agricultural areas of Georgia. As of this week, it appears that we have another hurricane poised to strike Georgia. University of Georgia Cooperative Extension wants all of its agents — and the fruit, vegetable and nut growers they serve — to be as prepared as possible for the effects of the storm.

Agricultural areas, particularly where vegetables are grown, are severely impacted by flooding events that result from heavy precipitation. When the edible portion of a crop is contacted by flood waters, the Food and Drug Administration (FDA) deems it “adulterated,” and the crop cannot be used as human or animal food. For this reason, the recommendation is to harvest vegetables and other edible products in advance of the rain, no matter the yield. As long as the total harvest costs are less than the delivered-in value of the produce at the processing plant or the packinghouse, harvesting is still profitable. In sum, harvesting decisions rest on determining an economic threshold for the grower.

Flooding is defined by the FDA as “the flowing or overflowing of a field with water outside a grower’s control.” Since chemical as well as microbial contamination is present in flood waters, there is no way to process fruits and vegetables that are contacted to make them safe again for consumption. If the crop field is flooded, but the water level is not high enough to touch the edible portion, a risk assessment may determine whether the product is likely contaminated or may be harvested. This includes crops that are still standing after the flood (e.g., tomato, bell pepper or eggplant) where the fruit is above the water level and too high for flood water to splash onto the product. Additionally, if the edible portion of the crop has not developed yet, the crop may be safe for future harvest.

UGA Extension specialists prepared a quick guide for Extension agents and growers to properly handle Hurricane Michael as it approaches:

Before an anticipated flood event:

  • Take inventory of and secure any chemicals and hazardous chemicals (e.g., herbicides, insecticides and fungicides).
  • Move any livestock, equipment or tools to elevated areas, preferably areas with no risk of flooding.
  • Use sand bags, berms or ditches and crosscuts to divert water around greenhouses, packinghouses, barns and produce fields.
  • Make copies of important documents and ensure that documents are stored in a secure, waterproof location, or take them with you in the event of evacuation.

 

After a flood event:

  • Contact your insurance agency before any clean-up activities, including salvaging crop fields where a portion of the produce was not contacted by flood water.
  • Clearly identify the highest point of flood water to make sure that contaminated product is not unintentionally mixed with “clean” product.
  • Harvest “clean” produce prior to handling nonharvestable produce to avoid cross-contamination of your produce.
  • If well heads were submerged, do not wash any harvested produce to avoid contamination. Test the water before any use.
  • Boil all water for personal consumption until test results indicate that no detectable generic Escherichia coli are present.
  • Take pictures of all damage immediately in order to send evidence to insurance agencies.
  • Allow a 60-day interval between flooding and replanting of previously flooded fields to allow for human pathogens to die off. Chemical hazards may still be present in previously flooded soils, so chemical and microbial soil testing should be considered prior to replanting.
  • Contact your UGA Extension agent if you are unsure whether produce can be safely harvested.

 

Remember, the more severe the rain, the higher the chance of contamination. For more information, see www.fda.gov and https://producesafetyalliance.cornell.edu

Silverleaf Whitefly Update

Oct 1, 2018 | Written by

Sep 26, 2018 | Written by                                                                               Silverleaf whitefly populations have increased in many areas in the last few weeks and will likely continue to increase as we stay above average temperatures. When we start to cool off at night, the population increases should slow down. We have been fortunate that we have not seen population explosions like we had last year. Part of this is likely the impact of a fungus that attacks whitefly. We saw a lot of it last year after the hurricane and are seeing impacts in many areas this year. When present, you will see fuzzy, white, dead adults stuck to the leaves. High humidity (which we have had even without rain) helps fungal attack on whitefly and other pests (unfortunately it also helps fungi attack plants). Hopefully we will experience cooler weather with some rain in the near future and help suppress the whitefly population growth.

Insecticide trials have mostly shown good efficacy with most of the products we usually use. We have seen reduced performance with imidacloprid (Admire Pro) and thiamethozam (Actara) – these two neonicotinoids are very similar and resistance has historically been worse with these as compared to other neonicotinoids. Coragen has also shown less efficacy than expected but is still providing some control. Insecticide resistance is always a threat and rotation of modes-of-actions is highly encouraged.