LAKE ALFRED, Fla. — If information is power, Florida citrus growers have a new asset in their fight against citrus greening disease which has been impacting the state’s multi-billion dollar citrus industry.
The University of Florida Institute of Food and Agricultural Sciences statewide citrus program launched a major revision of a website, providing instant access to a portfolio of information valuable to growers.
The citrusresearch.ifas.ufl.edu website underwent a major revision, making it easier to navigate, adding new access to research trials, publications and presentations.
“We know growers are busy and don’t have time to search multiple sites for information,” said Michael Rogers, professor and director of the UF/IFAS Citrus Research and Education Center in Lake Alfred, Florida. “We put the most current research in one website where growers can search for and find what they need to be successful in today’s challenging growing situation.”
The new site includes special features of interest to growers including:
Data from over 20 rootstock trials conducted by the UF/IFAS plant improvement team. Growers can review the data collected from the trials and compare data from sites across the state.
UF/IFAS researchers share their ongoing research priorities in citrus economics, grove management, new varieties, nutrition/water management, psyllid management and root health.
A resources section includes current production and nutrition guides and Extension documents (edis.ifas.ufl.edu) on citrus-related topics from 2016 to the present that are easily linked to from the website and are also presented by researcher for easy searching.
“This website is just one of the ways that the UF/IFAS citrus team is working to support growers with the latest science to best battle citrus greening. We are working to get this information directly to growers as soon as it is available so that they may be able to put it into action as soon as possible,” Rogers said.
According to a University of Florida/IFAS blog, the corn earworm is especially concerning to corn and tomato growers. It causes serious damage when it feeds on corn silk and kernels and tomato fruit.
Corn earwom adult. Photo credit: J. Capinera, University of Florida
In corn, eggs are laid on silk and the caterpillar hatches and feeds on silk and kernels. In tomato, eggs are laid on leaves, flowers or fruit. The caterpillar feeds by burrowing into tomato fruit. The corn earworm prefers warmer climates. Adult moths migrate north from southern states and can overwinter as far north as Ohio and Kansas.
Caterpillars are a common pest of vegetable plants. They can reduce fruit quality and yield by feeding on leaves or fruit. One important caterpillar pest is the corn earworm (Helicoverpa zea). This caterpillar develops into a relatively harmless nondescript moth, but the caterpillar causes major crop damage in corn and tomato. It is also known as the tomato fruitworm, cotton bollworm, soybean podworm, and sorghum headworm. Some experts consider it one of the most damaging pests in the United States.
Identification
Identification of caterpillars can be difficult and may require the assistance of an expert. Caterpillar body color is variable and can change as it grows older. They can be brown, green or even pink. There is usually a pair of narrow stripes that run down the back. There is also usually a white net pattern on the head. Adults are also difficult to identify. They have brown to yellow forewings with a dark spot in the center.
Lookalike
The corn earworm is established in the United States, but it looks identical to the old world bollworm (Helicoverpa armigera) which is considered an invasive pest. In order to distinguish the two species, DNA molecular analysis or dissections must to be performed by an expert. If you find a caterpillar that you are unsure is the corn earworm or the invasive old world bollworm, contact the FDACS-DPI help line at: DPIHelpline@FDACS.gov or 1-888-397-1517.
Pecan producers will soon enter a critical point in this year’s production season in ensuring their trees have adequate moisture. If the current dry period continues as expected into August, water needs will be even more essential.
According to UGA Extension Pecan Management calendar, water needs increase from 120 to 158 gallons per tree per day in July to 300 to 350 gallons per tree per day in August. The needs increase from 1,440 to 1,896 gallons per acre per day in July to 3,600 to 4,200 gallons per acre per day in August.
“If we turn off really hot and dry in August and September, which we have seen happen many times in the past, if you’re not watering adequately during that time, mid-August through September, you can lose a lot of your crop,” University of Georgia Cooperative Extension pecan specialist Lenny Wells said. “Especially when they’re really loaded, there’s a huge water demand there. If they get stressed at all for water in a situation like that, they’ll start aborting nuts. It would be a big problem.
“We really need to get really good kernel fillings. We do need a few timely rains during that mid-August to that mid-September period to really help us get kernels filled like we need. Especially when the trees are this loaded.”
Irrigation will be critical. According to Pam Knox, UGA Extension Agricultural Climatologist, hot and dry conditions are expected to persist throughout the Southeast for the next month.
It is never too early start thinking about next year’s Southeast Regional Fruit and Vegetable Conference. In the age of the coronavirus pandemic, industry leaders like Charles Hall, executive director of the Georgia Fruit and Vegetable Growers Association, must start thinking about an event still several months away.
“We’re operating on the premise that we’re going to have a show in January in Savannah (Georgia). But we’re looking at, if the outbreak doesn’t calm down, if the requirements are such that we can’t hold the show, we’re looking at what the options are,” Hall said. “We’re just trying to do some preliminary, looking at different ways of doing that and whether we have virtual shows, live presentations. We’re just hoping that things calm down enough that we can have the show and get things going from there.”
Scheduled for Jan. 7-10
The conference is slated to be held in Savannah, Georgia on Jan. 7-10. It’s one of the largest events in the Southeast. It attracts 3,200 attendees and 280 companies that have booths to showcase their agricultural products.
Hall believes a final decision will be made in the fall on whether the conference will be in-person or virtual. A lot will depend on the availability of companies being able to travel for meetings at that point.
“If some of the national companies make the decision that their employees can’t travel in January, that will begin to affect our decision of whether we do with the conference,” Hall said. “We will have a conference. The real question is, hopefully, we’ll have an in-person conference and not a virtual conference.”
The other dilemma is if the conference proceeds as normal, how will social distancing guidelines be followed with that many people expected to attend?
“Right now, if we had that conference in Savannah, you would have to be at a 50-person maximum in a room. I think is what the requirements are, and then they have to be social distancing. Those classrooms have been wall-to-wall people and they’re standing along the sides, you can’t have that many people in a classroom right now,” Hall said.
The watermelon market continues to be a sweet success for producers in the Southeast. One South Georgia watermelon farmer attests to the strong season he and his colleagues have had this year.
Watermelons for sale at the Farmers Market in Cordele, Georgia.
Bill Brim, co-owner of Lewis Taylor Farms, said on July 10 that he is had an “excellent year” with his watermelon crop.
“Prices dropped a little bit after (July) 4th. But I think they’ll pick back up after about another week. We’re still harvesting melons. We’ll probably still harvest for another 10 days any way before we’re done,” Brim said.
Similar to a belief shared by farmer Carr Hussey, Brim believes there may soon be a shortage of watermelons available in the U.S.
“There’s going to be a gap in there, probably about a two-week gap, I think. Talking with some guys up in Indiana, they’re already harvesting a few melons that they had on their hoops; but they didn’t’ have many acres on their hoops,” Brim said.
Crop Shortage
Hussey, a watermelon farmer in Florida and Alabama and chairman of the board of the Florida Watermelon Association, said there may soon be a shortage as producers in the Southeast region finish harvesting their crop, while the northern states are still not close to begin picking their crop.
He believes the cool, wet spring impacted the crop’s production and why there is less watermelons than normal.
Another South Georgia producer, Terrell Rutland, said farmers in the Carolinas and Midwest normally plant three or four weeks after he does but their plants were damaged by a late spring frost. They replanted, which delayed their harvest window another three weeks.
Acreage is down in Georgia this year. According to Samantha Kilgore, executive director of the Georgia Watermelon Association, acreage is projected to decrease this year to 19,000 acres. It would mark a significant drop from previous years’ harvests. According to the National Agricultural Statistics Service, from 2016-2018, Georgia averaged a harvest of just more than 23,000 acres.
The Environmental Protection Agency is re-evaluating the risks of Carbaryl for continued registration of this chemical. In order to protect Carbaryl for use, the Florida Fruit and Vegetable Association is surveying growers on its use. Your data is critically important. Even if you do not use Carbaryl, input is needed.
The Cabaryl case study will be presented as part of a national workshop later this year or early next year. Be aware that some products use the name “Sevin” but do not contain Carbaryl. Please take the survey and send it to Mike.aerts@ffva.com.
UGA photo/Onion center rot is a financially devastating bacterial disease for Vidalia onion producers in south Georgia.
By Maria M. Lameiras for CAES News
After years of building and analyzing sample collections, plant pathologists at the University of Georgia have identified the genes that allow a type of bacteria that causes onion center rot to resist onions’ natural defenses in a “chemical arms race.”
The pathogen Pantoea ananatis can enter onions through the leaves — usually as a result of thrips feeding on the onion neck — and induces necrotic symptoms and extensive cell death in onion tissue.
When cellular damage occurs, onions and other members of the Allium genus, such as garlic, produce volatile antimicrobial compounds called thiosulfinates, the same compounds that make you cry when you cut onions and that give onions and garlic their characteristic smell and flavor.
These compounds normally kill invading bacteria. However, an 11-gene cluster of the P. ananatis genome allows the bacteria to tolerate the thiosulfinate allicin and colonize dead onion tissue damaged in its initial attack, according to a paper published this month in the journal Current Biology.
Center rot of onion, caused primarily by P. ananatis in the Southeast U.S., can be economically devastating to producers, leading to high crop losses both in the field and postharvest, said Brian Kvitko, an assistant professor in the Department of Plant Pathology at the UGA College of Agricultural and Environmental Sciences and lead author of the study.
Kvitko’s research into this pathogen is important because the bacteria resist onion’s natural defenses.
“Onions are a tricky host. Anyone who has ever cut onions knows they release a very potent irritant that can kill some bacteria, but these bacteria have a one-two punch,” Kvitko said. “The onion releases thiosulfinate, a potent reactive sulfur species that causes gross damage to cells by interfering with all kinds of cellular processes. The bacteria have picked up genes that allow it to take the hit from the thiosulfinate and then take over the dead onion tissue environment as a home to make more bacteria. Like little genetic gas masks. The onion itself already had built-in antibiotics and these bacteria found a way around it.”
Kvitko said that these bacteria cause disease differently than most other bacteria, which either break down plant cells walls with enzymes or “reprogram” plant cells by injecting them with proteins.
“So, bacteria can chew up the plant cells or reprogram them, but this is neither of those. These are not proteins that are being delivered, it is a chemically focused kind of disease. This is not the only example of this we have seen, but it is very rare,” he said.
Through genome sequencing, Kvitko’s lab identified differences in the P. ananatis genome from similar bacteria.
“These bacteria did not have any of the traits that were associated with a pathogen we knew. It was strange, but we didn’t know why. Now we have been able to find this different way of bacteria causing disease,” Kvitko said. “Knowing more about the pathogen and how it causes disease helps us find treatment and resistance strategies to manage this disease in the future.”
Onion center rot was first identified in Georgia in 1997 and can cause latent infections that are activated postharvest even if there were no overt signs of disease in the field.
“This is kind of an insidious disease in that the producer sometimes doesn’t know there is a problem until the crop is harvested, packed and shipped,” Kvitko said. “This disease is a big problem in onion-growing regions because bacterial diseases are hard to manage. There are a lot of diseases caused by fungi that we have fungicides to control, but we don’t have that kind of chemical strategy for bacteria.”
Although there are currently no identified onion cultivars with resistance to P. ananatis, knowing how a pathogen causes disease is a good step toward knowing how to find good host resistance, he added.
“To be able to fight something effectively, you have to know how it works. We know this thing is different. Knowing why and how it causes disease helps us to find a better way to fight it,” Kvitko said.
A key part of the research is the work being done by Bhabesh Dutta, assistant professor of plant pathology and UGA Cooperative Extension vegetable disease specialist on the UGA Tifton campus, who has collaborated with growers by collecting extensive samples of diseased plants for analysis. He then works with Kvitko on research both in the lab and in the field, an example of basic and applied agricultural research partnerships, which is a hallmark of collaboration and discovery at land-grant universities like UGA.
“We would not have made as much progress without Dr. Dutta’s long history with the systems and the good collection he’s been putting together for years,” Kvitko said. “The key thing that made this work wasn’t just collecting samples from diseased onions, but also from weeds in the fields and the thrips that are important in spreading the disease. That gave us a large panel of diversity to work from. We were able to look at all of the bacterial strains, even those that were very close to one another, to identify the genetic differences. We compared key regions of the genome that were only present in the strain that could infect onions. The genes that make specific regions of the genome different made the difference between which bacteria can and can’t cause diseases.”
With Vidalia onions at the top of the vegetable commodities grown in Georgia — at an annual farm gate value of $150 million — identifying the genetic traits of the bacteria responsible for the No. 1 disease in the state’s onion crop is an important factor in preventing financial losses for producers, Dutta said.
“There are 21 counties in Georgia with the marketing rights to grow and sell Vidalia onions, with nearly 65-70% of Vidalia onions being grown in Tattnall and Toombs counties,” said Dutta. “This is a high-value commodity for Georgia growers and this bacterial complex has become endemic in the Vidalia onion zone.”
While not all bacteria cause disease, Dutta’s research team has identified eight bacterial pathogens that are endemic to Georgia and which cause economic losses. Among the eight, one of the most prominent bacteria is Pantoea sp., which causes center rot. Other than Pantoea sp., Burkholderia cepacia — the causal agent of sour skin disease — is also prevalent in Georgia.
Building on a collection started by his predecessor, Ron Gitaitis, in the 1980s at UGA-Tifton, Dutta has assembled a collection of nearly 250 Pantoea bacteria strains from a diverse variety of sources including onions, weeds and thrips in his research program.
“Identifying the strain of bacteria that causes onion center rot allows us to survey producer fields and, if Pantoea sp. is prevalent in the environment, but it is not a disease-causing strain in onion, it gives us the ability to assess the risk that producer might have for center rot developing in onions during postharvest storage,” Dutta said.
Now that they have identified the 11-gene cluster responsible for the allicin resistance, Kvitko’s lab can start studying those genes.
“That’s where we are now. We know they have a cluster of 11 genes, but we don’t know exactly how it works. Is it specific to this type of bacteria? Or is there a way to keep bacteria from turning that resistance on?” Kvitko said. “Knowing more about the system, we have a nice list of potential weak points we can try to target, either through host resistance or some sort of novel chemical strategy. Bacteria are really tricky to manage; we have a limited tool set to work with and we want to have more.”
Because it would be impossible to change all P. ananatis bacteria, Kvitko’s team will also use what they’ve learned to develop pathogen-resistant onions.
“We are trying to see if there is any onion out there that the pathogen can’t kill. Finding onions that are resistant to the chemicals that are released by the bacteria and giving growers accurate information is important for mitigation,” he said.
An increasing likelihood of a La Nina weather event this fall could impact row crop farmers and specialty crop producers as well, said Pam Knox, University of Georgia Cooperative Extension Agricultural Climatologist.
“When we do have a La Nina, we do tend to have a little bit drier than normal fall. Dryness in the fall isn’t necessarily bad. It’s helpful for the people that’s trying to harvest. It’s just that if you’re trying to fill in the last of the pecans or get a little more growth out of the peanuts then dry conditions are not necessarily good,” Knox said.
According to the pecan production calendar, pecan’s water requirements are especially high in August and September. UGA pecan experts say water needs are 300 to 350 gallons per tree per day or 3,600 to 4,200 gallons per acre per day.
Knox said we are in a La Nina watch right now and is unclear how strong of a La Nina it’s could be.
“Typically, when we have a La Nina occurring, and right now we’re under a La Nina watch, the conditions in the Eastern Pacific Ocean are cooler than normal. They’re expected to stay that way. Usually it takes four months before they’ll declare an official La Nina,” Knox said. “The predictions are it might last until January or February and then go back to neutral conditions. It’s not necessarily one that’s going to be really long.”
The Florida Fruit and Vegetable Association (FFVA) did not get all of its wishes granted with the recent revisions to the Coronavirus Food Assistance Program (CFAP) by the United States Department of Agriculture. FFVA President Mike Joyner confirmed that there are two commodities that his organization hopes the USDA will include in Category 1.
Watermelons on display at a farm on the UGA Tifton campus. Watermelons are a commodity that the FFVA hope will be added to Category 1 of CFAP.
“The two commodities that we also submitted for consideration also in column 1; we had blueberries, but we also had celery and watermelons. We’re hoping that in that second round, the USDA approves those two commodities for column 1,” said Joyner, who added that 13 of the 29 commodities that FFVA petitioned for were revised by the USDA. “We submitted information in the NOFA (Notice of Funding Availability) that clearly made the argument that the losses for watermelons for about a four-week period, the price just dropped off the table.
“We appreciate the decision on the 13 of the 29. We hope that when the second round comes, they will approve the others.”
Had crops that suffered a five percent-or-greater price decline between mid-January and mid-April as a result of the COVID-19 pandemic,
Had produce shipped but subsequently spoiled due to loss of marketing channel, and
Had shipments that did not leave the farm or mature crops that remained unharvested.
According to the USDA press release, additional commodities were added to CFAP and that the USDA made other adjustments to the program based on comments received from producers and organizations and review of market data.
The USDA’s Farm Service Agency (FSA) is accepting applications for CFAP through Aug. 28.
It’s not just coastal counties, where the storms hit first, that are right in the path of destruction. Even inland areas, where much Florida citrus grows, are vulnerable.
“Hurricanes are very big systems, and their impacts often extend hundreds of miles away from the eye,” said Alferez, an assistant professor of horticultural sciences at the UF/IFAS Southwest Florida Research and Education Center. “One would tend to think that Southwest Florida is most prone to hurricane damage and think about Irma in 2017 or Wilma in 2005. Those were devastating for the southwest part of Florida.”
But commercial citrus operations throughout Florida can experience a hurricane’s wrath. Hurricanes Charley, Frances and Jeanne struck Florida in 2004. They impacted mostly the central Florida citrus region. Hurricane Michael in 2018 impacted the mandarin-producing areas in the Panhandle, not to mention strikes in the east coast damaging the grapefruit industry, said Alferez.
To try to minimize damage to citrus farms, Alferez outlines the important aspects of preparing for a hurricane:
Initial site planning is important. In general, ensure good drainage. Then, maintain the drainage infrastructure because flood prevention is key for citrus trees to survive.
Know and take care of your farm. Have an inventory of everything in place and updated.
Know your employees and care about them, train them and make sure you have insurance for the farm.
Have an emergency plan that includes follow-up and recovery plans. Have a clear chain of command.
After the storm strikes — before you do anything else — make sure it’s safe to get into the farm. If it is, document all damage. That includes taking photos. This will help with insurance claims. Then, start grove and tree recovery.
Some citrus varieties seem to be able to withstand the storms better than others, Alferez said.
“What we have seen so far is that Swingle rootstock and trifoliate rootstocks behave well and are not easily uprooted,” he said. “On the contrary, rootstocks such as Flying Dragon and Volkameriana did not perform well.”
Alferez and Mongi Zekri, a multi-county specialized citrus agent for UF/IFAS Extension in Southwest Florida, co-authored the guide. They wrote the document after the U.S. Department of Agriculture Southeast Climate Hub asked Alferez to develop a technical manual for citrus producers to build resilience to and recover from hurricanes or tropical storms.
The request came after Alferez spoke at a conference in Gainesville in November 2018. There, he talked about the effects of Hurricane Irma on citrus production in Southwest Florida. From there, the Climate Hub decided to develop a technical manual to help producers — farmers, foresters and livestock/grazing land managers — in the southeastern United States build resilience to and recover from hurricane events.
“The end product would be a consolidation of the best available management practices on citrus into one uniformly designed manual that could be used by Extension agents to provide preparatory and recovery resource-specific guidance to citrus producers,” Alferez said.
