File photo shows whitefly adults feeding on a yellow squash seedling.
According to the South Florida Vegetable Pest and Disease Hotline, whiteflies are flaring up in tomatoes and watermelons in Southwest Florida. In the Central Florida area, growers indicate that whiteflies are present in tomatoes low numbers, although some of the early plantings were hit hard by whiteflies.
Tomato Yellow Leaf Curl Virus pressure remains less than 1% but it is present in nearly every planting.
Growers in Homestead, Florida indicate that whitefly numbers are present in oriental vegetables.
Management of whiteflies later in the season depends on early suppression of whitefly populations. Growers need to be aggressive with systemic materials like Venom, Sivanto Prime and Verimark, early in the season.
Proper scouting remains a viable management tactic for controlling silverleaf whitefly. University of Florida entomologists have established thresholds that have been successful for tomato producers.
For more whitefly management tips, see click here.
File photo shows how whiteflies can infest fall cucurbits.
University of Georgia Cooperative Extension vegetable entomologist Stormy Sparks is more optimistic about the ongoing whitefly problem that farmers are facing this fall – especially more than what he was feeling two weeks ago. His reason for optimism? Remnants from a hurricane and a drop in temperatures.
Remnants from Hurricane Sally and cooler weather this week should help knock back some of the whitefly populations, which were wreaking havoc on fall vegetable crops.
The rain amounts were extreme in certain places last Thursday when the storm moved across the state. More importantly, the rain was widespread.
“I would anticipate that the weather knocked down the adult populations and this cool weather will greatly delay or reduce the amount that they rebound. That’s what I would think would happen,” Sparks said. “The main thing was (the rain) was everywhere. We got some everywhere. That probably has much more impact than those local heavy rains that we normally get.”
Weather Conditions
According to the UGA Automated Weather Network, Cordele, Georgia received 5.3 inches on Thursday, Sept. 17, while Moultrie, Georgia received 2.36 inches.
Temperatures also dropped from 81 degrees Fahrenheit on Sept. 16 to 67 degrees F on Monday, Sept. 21 in Moultrie.
Whitefly Infestations
Whiteflies have been a problem all year, dating back to early spring. An abnormally mild winter did not kill off many of the wild hosts that whiteflies overwinter on. The result was they became mobile earlier this past spring.
Whiteflies cause feeding injury issues in vegetables and transmit two viruses: cucurbit leaf crumple virus and cucurbit yellow stunting disorder virus. Vegetables like squash, zucchini, cucumber, cantaloupe and snap beans are highly susceptible to these viruses. Commercial cultivars that have resistance or tolerance to these pathogens are not available.
UGA CAES photo/Ashfaq Sial is leading a multistate team of researchers to develop and implement long-term sustainable strategies to control spotted wing drosophila.
By Emily Cabrera for CAES News
The University of Georgia College of Agricultural and Environmental Sciences (CAES) has been awarded a $5.4 million grant by the U.S. Department of Agriculture’s National Institute of Food and Agriculture to develop long-term, sustainable methods for controlling the spotted wing drosophila (SWD).
Native to Asia, SWD is a tiny fly that was first detected in California in 2008 and has since emerged as a devastating pest of small and stone fruits throughout the U.S., valued at $5.8 billion in damage annually. It affects soft-skinned fruits such as blueberries, blackberries, raspberries, strawberries, cherries and others.
Blueberry entomologist and coordinator of the UGA Integrated Pest Management Program, Ashfaq Sial is leading a multistate team of researchers from 10 land-grant universities and the USDA to develop and implement long-term sustainable strategies to control SWD.
The pest has caused blueberry crop losses of up to 20% annually. Blueberries are Georgia’s top fruit crop and ninth-largest agricultural commodity with an estimated $300 million in value, according to UGA agricultural economists.
This project builds on previous work to develop control strategies in response to the crisis situation created after the detection and widespread distribution of this devastating invasive pest in all fruit-growing regions of the U.S. The team made substantial progress by refining monitoring tools, developing effective insecticide-based management programs, identifying effective cultural controls, and screening native and exotic biological control agents to address the drosophila invasion.
“The progress we’ve made is great, but SWD management is still highly insecticide dependent and is further challenged by secondary pest outbreaks, insecticide resistance and increased input costs,” explained Sial. “Because SWD has become established as a keystone pest throughout the U.S., it’s critical to develop more sustainable strategies to manage it.”
The goal of this new project is to pivot away from crisis response to build a long-term, integrated and systems-based approach to managing SWD. The team will work with region- and crop-specific teams of growers to implement best management programs, evaluate alternatives to insecticides, assess and reduce the risk of insecticide resistance development, and develop and disseminate actionable recommendations that enable producers to optimize pest management decisions for sustainable SWD management. They will also develop economically based decision aid tools to increase profitability and evaluate the impact of these initiatives.
The team aims to develop and deliver systems-based integrated management programs to berry and cherry growers that are cost effective and environmentally sustainable for long-term management of SWD in the U.S. Ultimately, implementing these solutions will directly contribute to the long-term profitability and sustainability of farms and farmers nationwide.
Joining Sial on this project is Kay Kelsey, a professor and evaluation expert in the CAES Department of Agricultural Leadership, Education and Communication. Other collaborators and their institutions include Hannah Burrack, North Carolina State University; Kent Daane, University of California Berkeley; Rufus Isaacs, Michigan State University; Greg Loeb and Miguel Gomez, Cornell University; Cesar Rodriguez-Saona, Rutgers University; Philip Fanning, University of Maine; Elizabeth Beers, Tobin Northfield, Karina Gallardo and Gwen Hoheisel, Washington State University; Vaughn Walton, Oregon State University; Joanna Chiu and Frank Zalom, University of California Davis; and Kim Hoelmer and Xingeng Wang, USDA Agricultural Research Service in Newark, Delaware.
Pictured is a stink bug, an insect that farmers can target with trap cropping.
Ayanava Majumdar, Extension Professor in Entomology and Plant Pathology at Auburn University, touts trap cropping as being effective in controlling unwanted insect pests while also significantly reducing insecticide applications.
“Not all insects will trap crop work. Trap crop works for insects that typically stay in clusters or have a strong border effect. For example, our sucking insect pests like the stink bugs, aphids; they all show a very clumped distribution and have a very high edge effect and then they spread,” Majumdar said. “Those are the insects, especially the migratory insects, that you can arrest; stopping them from going into the main crop.”
Trap crops are sacrificial crops planted around a field that are not meant to be harvested. Producers plant them to draw pests away from the real crop. There is no universal trap crop available. Different insects require different trap crops.
Insects love different kinds of plants. Stink bugs will attack tomatoes, so if farmers provide a distraction like sorghum, they will go to that distraction and stay away from tomatoes.
Majumdar said the trap crops evaluated in Alabama include sorghum and sunflower for leaffooted bugs; sunflower, browntop millet and pearl millet for stink bugs; okra, bell peppers and ornamentals for aphids; New England Hubbard squash for squash insects.
He recommends growers plant a trap crop two weeks ahead of a main crop, for a perimeter trap crop where it envelops an entire field.
Some advantages include farmers can use existing farm equipment; there is minimum new investment (seed); producers can reduce damage to the main crop; and it attracts and conserves beneficial insects.
“The challenge is to become efficient in doing it, not devoting more than 10% or 15% of the total area in trap crop so that you don’t cut back on the land and main crop,” Majumdar said.
UGA photo/Yellow jacket encounters spike this time of year. As we spend more time outdoors, we’ll see yellow jackets and wasps foraging more often.
By Emily Cabrera for CAES News
As the weather cools across the state, several fall insects will begin to take center stage around Georgia homes. Be on the lookout for these nuisance pests and make preparations to deter them from entering your home for the winter.
Asian Needle Ants
University of Georgia entomologist Dan Suiter tells homeowners to be on the lookout for a particularly problematic ant called the Asian needle ant (Brachyponera chinensis). This invasive species was first reported in the U.S. in the 1930s in Decatur, Georgia.
“For decades, this ant hasn’t been considered an issue, but over the past several years population sizes have exploded, and they are now a major pest in Georgia, especially in the northeast and northwest,” explained Suiter.
Unlike the more widely known fire ant or Argentine ant — commonly referred to as the “sugar ant” — the Asian needle ant does not build mounds, so it can be difficult to spot this ant species. They establish colonies of up to a couple thousand ants by nesting under logs, stones and bark. When disturbed, they can deliver a very painful sting, similar to fire ants, but the venom can be quite toxic — even fatal, in some cases, should sting victims suffer from anaphylaxis.
Many pest ant species lay down pheromones to help establish a well-defined foraging trail for other ants of the same colony to locate food sources, but the Asian needle ant does not forage in this manner. They instead exhibit a very unusual behavior called “tandem carrying,” where one female worker ant will carry another worker ant in her mandibles. Once a food source is located, she will put her sister down and they will forage together.
“The other interesting and somewhat alarming thing about this species is its ability to quickly devastate other native ant species by either taking over their nest sites, consuming their food or by directly preying upon them,” Suiter said. “In the spring while temperatures are still cool, the Asian needle ant will become active and begin establishing colonies before other ant species, so they tend to dominate available habitat earlier and are driving local extinctions of other ant species where we’ve seen them colonizing.”
County University of Georgia Cooperative Extension agents and forest service employees have been reporting higher incidences of this species in the last few years, especially in northeast Georgia.
“We’re not exactly sure of their range yet, but they are probably not as common in south Georgia as they are in north Georgia,” said Suiter.
Argentine Ants
A familiar occurrence for anyone who lives in Georgia is the annual migration of Argentine ants into homes during the fall and winter months. “When we start having cold snaps beginning in October, this ant will start to invade homes looking for a warm place to overwinter,” explained Suiter.
Argentine ants don’t go into diapause like other insects, so this migration indoors is a survival mechanism to get through the winter. They will typically find overwintering spots in walls and around electrical devices that put off heat, such as printers or refrigerators.
“Argentine ants are what most of us call ‘sugar ants.’ They don’t really bother us during the summer, as they spend most of their time in trees foraging for honeydew from aphids and scale insects,” said Suiter. “This species can have hundreds of queens within a colony, so they spend all summer building their colonies and this is the time of year that population sizes peak — just before coming indoors — so they quickly become a nuisance of homeowners right about now and into winter.”
Suiter recommends heading off issues now before they become a problem in the upcoming weeks and months. He tells homeowners to clean up outside of structures to help prevent these ants from collecting and moving indoors. “Argentine ants thrive in mulch and leaf litter because they hold moisture, so horticultural mulches and leaf litter should be minimized. Try not to allow leaf litter to collect in gutters and around the base of homes,” instructed Suiter.
If insecticide use becomes necessary, available commercial products that contain fipronil, such as Termidor or Taurus — a liquid insecticide — can be mixed with water and applied directly to ants found outside. Never spray these products indoors!
“It is sometimes advisable to find ant nests in mulch and leaf litter and spray nests directly,” explained Suiter. “Typically, no more than 1 gallon of diluted, finished product is needed to control Argentine ants on the outside.”
Suiter reminds homeowners to always read and follow the product’s label, as the label contains the manufacturer’s directions for use and provides instructions on what can and cannot be done with the product. Many insecticides, for example, are toxic to fish and other aquatic life and should never be used in areas where they can get into water.
Wasps and Yellow Jackets
Lastly, be mindful of wasps and yellow jackets this time of year. As the weather becomes cooler and more tolerable, people tend to spend more time outdoors, where entertainment often includes food and drink. This is also the time of year that wasp and yellow jacket population sizes are at their peak.
“As we know, tailgating and fall barbecues are always a favorite pastime this time of year, but this is also the time that yellow jacket encounters spike,” explained Suiter. “When we see wasps and yellow jackets in these social settings it’s important to understand they are not approaching you in a protective or aggressive manner, as they aren’t trying to guard their nest. They’re interested only in foraging from whatever food you have lying around. So, we recommend that people not swat at them or panic, but just be sure to check your soda can before taking a sip to avoid being inadvertently stung.”
Alabama fruit and vegetable growers need to be aware that moths are still active across the state. According to the Alabama Extension Commercial Horticulture Facebook page, the number of fall and yellowstriped armyworms, soybean loopers, corn earworms and vine borers continues to rise.
Pictured is a fall armyworm.
There is a risk of infestations in vegetable crops from caterpillars. Scout and control these early. According to the Alabama Extension Commercial Horticulture Facebook page, moth counts were collected from pheromone traps in 20 locations across the state.
As of Sept. 8, there was 269 fall armyworms moths collected, compared to 149 on Aug. 15. This is a 1.8x increase over two weeks. They are very migratory and move up from Florida where they overwinter. There are 4 to 5 generations per year.
The moth numbers for yellowstriped armyworm were 133, compared to 97 on Aug. 15. They have four generations per year. The larvae have black triangular markings dorsally with white or yellow lines below.
Soybean loopers increased from 139 to 214. Loopers feed on host plants like soybeans, peanuts and other legumes.
Squash vine borers increased from 311 to 466, a 1.5x increase. These are day flying moths and are worse on organic farms.
Corn earworms increased from 139 to 214. They are highly migratory moths with five to six generations per year. Their host plants are corn, tomato and cotton.
Moth species with more than 1.5x activity increase over the previous reporting period are a high risk to crops.
University of Georgia Cooperative Extension vegetable entomologist Stormy Sparks paints an ominous picture of the potential devastation whiteflies will have on this year’s fall vegetable crop.
“We’re probably a month ahead of the last two years. This is going to be challenging fall for whiteflies,” Sparks said.
Vegetable producers across the Southeast have either planted or are currently planting their fall crop. Sparks insists that farmers use resistant varieties when possible to protect against whiteflies and the diseases they spread. Unfortunately, there is not many that are commercially available, except in tomatoes.
“Really, when you’re dealing with viruses, particularly the whitefly-transmitted viruses, the solution to the problem is resistant varieties. The problem is in many cases we don’t have that. The one where we do have it is Tomato Yellow Leaf Curl (virus),” Sparks said. “Fortunately, we have resistant varieties in tomatoes that are commercially available. In the fall you’ve got to have a resistant variety.”
In most cases, whitefly-transmitted viruses are just as devastating as the whiteflies themselves. There is no resistance in yellow squash. In snap beans, there are severe problems with Cucurbit Leaf Crumple Virus and Sida Golden Mosaic Virus.
“With leaf crumple virus right now, in squash; I’ve been planting squash for two months, the most recent planting I’ve probably got about 20% virus right now. If you look at it historically, you go from very low to about 20%. Once you get about 20%, give it about another week or two weeks, you’re typically looking at close to 100%,” Sparks said. “As far as viruses are concerned, at this point, it’s not as bad as I thought it would already be, but I still suspect it’s going to get very ugly in the near future. We did have virus detected in the spring crops late in the season; more than normal. Dr. (Josh) Freeman down in Quincy (Fla.), said in some of his tomato trials in the spring, at the end of the season he had as much as 30% Yellow Leaf Curl Virus. Normally, it’s going to be 5% or less.”
Proper Sanitation
Sparks insists growers practice proper sanitation to protect against future whitefly infestations. Once farmers are through harvesting their crop, they need to get rid of it. If plants are left in the field, they could potentially serve as hosts for whiteflies.
Problem This Year
This is the worst year for whiteflies since 2017. They are a greater problem this year due in large part to the mild winter. While colder temperatures do not eliminate whiteflies, they do kill off many of their wild hosts and slow population development in cultivated hosts. Warmer temperatures allowed for larger whitefly populations to overwinter and become mobile earlier this summer.
Whiteflies migrate from winter vegetables to spring vegetables to agronomic crops, like cotton, to fall vegetables and back to winter vegetables. Whiteflies cause feeding injury issues in vegetables and transmit two new viruses: cucurbit leaf crumple virus and cucurbit yellow stunting disorder virus.
A yellow squash plant is infected with whitefly-transmitted cucurbit leaf crumple virus. Discolored fruits are typical following infection with this virus.
One of the best management tactics for vegetable growers when dealing with whitefly infestations is to get rid of any plants left in the field once harvest season is done. University of Georgia Cooperative Extension vegetable entomologist Stormy Sparks continues to preach proper sanitation to producers amid the worst whitefly outbreak in Georgia since 2017.
“This is really for all pests but definitely for whiteflies, when you get done with a crop and if you’re not managing that crop for whiteflies and it’s a crop that hosts whiteflies, you need to get rid of it as soon as possible,” Sparks said. “It needs to be destroyed so it cannot harbor or produce any more pests. That really should become a priority. In vegetables, getting a crop in on time is just paramount, nothing stops that. We really need to move towards that as far as getting crops out as well.”
Huge Problem This Year
Whiteflies are a greater problem this year due in large part to the mild winter. While colder temperatures do not eliminate whiteflies, they do kill off many of their wild hosts and slow population development in cultivated hosts. Warmer temperatures allowed for larger whitefly populations to overwinter and become mobile earlier this summer.
Whiteflies migrate from winter vegetables to spring vegetables to agronomic crops, like cotton, to fall vegetables and back to winter vegetables. Whiteflies cause feeding injury issues in vegetables and transmit two new viruses: cucurbit leaf crumple virus and cucurbit yellow stunting disorder virus.
Tomato planting is currently underway across the Southeast. It is never too early to start thinking about insect pests that could hinder fall production in Alabama.
According to the Tomato Insect Pests 101 video, Ayanava Majumdar, Auburn Extension Professor in Entomology and Plant Pathology, cautions growers to scout their tomato fields every week for pests and look for insects over and under the leaves and also at the plant base.
Tomato plants have five growth stages during the production season: seedling, vegetative, flowering, fruit formation and mature fruiting.
“Seedling and fruiting stages are most vulnerable to insect attack,” Majumdar said. “They must be protected.”
What to Watch for?
Early season insect pests include flea beetles, thrips and aphids. Flea beetles’ ability to chew small round holes across the leaves can lead to death for small tomato plants. Thrips have piercing-sucking mouthparts and can transmit viruses when feeding. Aphids suck plant sap and produce honeydew resulting in sooty-mold fungus.
Specific insects, such as the brown stink bug and leaffooted bug, can cause quality losses. Stink bugs have piercing-sucking mouth parts. Its feeding causes extensive fruit discoloration. These are often unmarketable and can rot fast in storage. Leaffooted bugs have leaf-like expansion on their hind legs. They aggregate in large numbers on fruits.
Caterpillars can cause holes on tomatoes. Beet armyworms, fall armyworms, yellowstriped armyworms, southern armyworms, fruitworms, hornworms and loopers are pests to watch out for. Fruitworms make round holes with the head tucked inside the fruit. Hornworms feed on the leaves, stems or entire fruit. Loopers are often late-season pests in Alabama.
Majumdar implores farmers to apply pest management tactics. This includes: plant and harvest your crop in a timely fashion; use pest exclusion fabric or netting early to stop moths and stink bugs; and use conventional or organic insecticides if needed.
Alabama hemp producers are tackling one pest after another this growing season. They started with fire ants not long after the crop was planted. Now, according to Katelyn Kesheimer, Auburn University Assistant Professor and Extension Specialist, the key insect is corn earworm.
Photo shows corn earworm adult.
“They’re really hard to control because they start small. Then they’ll be eating and eating and eating and you don’t see them until you see the damaged buds, or you really do some destructive sampling to get at those tiny first n-stars. Instead of having one big egg lay, it’s kind of like a sustained egg lay that we’ve seen in the last couple of weeks,” Kesheimer said.
The caterpillars feed on the buds and can cause significant yield loss, because they eat so much as they grow. As they chew, they also open that plant and some pathogens can get it and farmers could end up with bud rot.
Hemp is flowering throughout the state, which makes it most susceptible to infestations. It is the perfect time of year for corn earworms to be a problem as well. They move from crop to crop.
“Corn is being harvested, cotton is drying down and it’s the same flights that started a few months ago. They start in corn and they move to cotton and now they’re going to hemp,” Kesheimer said. “It’s a nice, lush green crop for them to lay eggs in. I think it’s just the timing and we have just a lot of insects in the system. It was kind of slow for a little bit but the last couple of weeks have really picked up.”
Kesheimer noted that producers have a plethora of products to utilize but spray coverage remains the key factor in managing the worms.
“Here in Alabama we have probably almost 100 products labeled for hemp. But the most important thing for the worms is getting really good coverage. You have to get really high volumes to get into those dense canopies where the buds are where the worms are hiding,” Kesheimer said.
