According to the South Florida Pest and Disease Hotline, bacterial spot disease is active in tomato and pepper fields on the east coast and around southwest Florida.
It is present at moderate levels in older hot pepper plants. Bacterial spot disease flares up after rain events and with fog in tomatoes and non-resistant peppers across the southwest region of Florida.
Reports from the Manatee Ruskin indicate low levels of bacterial spot in susceptible peppers. Farmers and scouts in Homestead, Florida report the disease is present in tomato and susceptible pepper varieties.
Bacterial spot is a serious threat to tomato and pepper production in Florida. It spreads quickly during warm periods with wind-driven rains. Fruit symptoms lead to reduced marketability.
Symptoms on tomatoes include distinct spots with or without yellowing. Fruit spots often begin as dark specks with or without a white halo. As spots increase, they become raised and scab-like.
Click here for additional information on bacterial spot.
Bob Spencer, with West Coast Tomato in Palmetto, Florida, believes there is light at the end of a year-long tunnel for the state’s tomato producers.
As more states continue to reopen combined with the recent passage of the America Rescue Plan, there appears to be good news on the horizon for Florida tomato producers who have struggled from the onset of the coronavirus pandemic.
“We’re starting to see a little bit of sunlight here over the last two weeks as more and more states are reopening restaurants. You’ve got New Jersey, New York, Michigan, Illinois, Ohio starting to reopen. It’s definitely helped our market,” Spencer said. “During the same period of time that we were experiencing the restaurant shutdowns, Mexico came in with a huge volume. It dumped a lot of cheap product into the country in violation of the agreements that we have them. It’s been a tough three months. But there’s definitely light at the end of the tunnel as these restaurants start to reopen.”
Pandemic Impact
Spencer estimated in a story in VSCNews in April 2020 that his company was losing 90% of his business. With food service being shut down for an extended period, this was devastating news for an industry that designates 70% to 75% of its crop for food service. And it could have been a lot worse.
“We were fortunate last year when it hit that we were still dealing with the after-effects of the new Suspension Agreement with Mexico. As a result, they had planted less acreage in the prior summer. That meant we had less product coming in to compete with us,” Spencer said. “While it was tough for us, it was not as bad as it could have been. Mexico had planted less, not knowing what was going to be the outcome of all the litigation around the suspension agreement.”
That changed this year, however. Spencer said Mexico overplanted and started dumping in low-cost tomatoes, which adds to tomato producers’ frustration.
“The reality is it’s the Commerce Department responsible for enforcing the agreement. In reality, it’s the equivalent of having Barney Fife as your security guard. They aren’t set up to enforce agreements,” Spencer said. “It’s just very difficult to get them interested in doing the kind of work to enforce the agreement. We’ve been dealing with it since 1996.”
But Spencer remains optimistic times are looking brighter for the state’s tomato industry.
“The springtime looks better (though) with the restaurants reopening,” Spencer said. “You’ve got restaurants reopening and you’ve got Uncle Sam sending everybody a check. Hopefully, people will use part of that check to go out to dinner.”
The most important decision farmers can make when growing tomatoes in Alabama is variety selection.
Joe Kemble, Alabama Extension vegetable specialist, insists that growers understand what varieties grow well in Alabama before they plant this spring.
“Easily the most important decision you can make is picking which varieties to grow. You can buy local transplants. It’s always great when you can do that. But what I’ve typically found is, often, the selection tends to be pretty narrow,” Kemble said. “There are literally thousands of tomato varieties out there. Many of them are adapted very well to growth in Alabama but unfortunately, some of them are not.
“Sometimes you may be growing varieties and you’ll say to yourself, I really don’t know why these are doing so poorly. The problem is, it may be the fact that it’s just not a very good variety to grow.”
Kemble said it is important to choose variety that will spread your season. Some are better for early in the season. Others are more tolerant of the high summer temperatures and can be grown in mid-to-late season.
“Try to pick varieties that are actually suited to the time of year you wish to grow them,” Kemble said.
Disease resistance is also an important factor to consider. Try to select varieties with resistance to tomato spotted wilt virus, nematodes, fusarium, late blight and early blight. Resistant varieties mean growers don’t have to apply fungicides to control the disease.
Kemble recommends the following tomato varieties: Bella Rosa, Carolina Gold, Crista, Mountain Gem, Mountain Magic, Mountain Merit, Red Bounty, Red Defender, Red Mountain, Rocky Top and Tribute.
Root samples of the rootstock Solanum sisymbriifolium (left) and Roadster tomato (right) are from a field infested with southern root-knot nematode M. incognita. Galls produced by the nematode are visible on the tomato root, while the rootstock root is free from nematode damage.
By Abolfazl Hajihassani
Tomato is the most economically important vegetable crop in the United States and has a history of heavy dependence on pesticides.
PATHOGEN PAIR
Root-knot nematodes and southern blight disease are among the most damaging pathogens of tomato. Pre-plant soil fumigation is often, but not always, effective at minimizing yield losses due to soilborne nematode and fungal pathogens. The fumigant 1,3-dichloropropene is only effective against nematodes and is not effective against soilborne fungal diseases. In contrast, the nematicidal efficacy of the fumigant chloropicrin is not the primary reason for its application against nematodes, as it mainly has fungicidal activity.
Fumigants for control of these pathogens are diminishing due to environmental concerns and increasing regulations and restrictions on the use of these chemical treatments. Therefore, alternative control strategies have been extensively investigated over the past decade. Grafting tomato onto rootstocks with resistance to multiple root-knot nematode species combined with application of non-fumigant nematicides could offereffective management strategies that would provide growers with additional tools for managing root-knot nematodes. Moreover, using resistant rootstocks is one of the most effective methods to manage southern blight disease.
Using a three-year award funded in 2019 by the U.S. Department of Agriculture National Institute of Food and Agriculture Methyl Bromide Transitions program, the University of Georgia (UGA) is investigating the effectiveness of a rootstock (Solanum sisymbriifolium) in managing root-knot nematodes and southern blight disease of tomato. Replicated field trials under experimental and commercial production conditions in Georgia are underway.
Root-knot nematodes (Meloidogyne spp.) are tiny parasites that feed inside roots, induce galls (which contain nematode eggs) and disturb water and nutrient uptake from the soil into the plant, thus reducing crop yields. Root-knot nematodes cause approximately $15 million in damage annually to U.S. tomato production.
In Georgia, five species of root-knot nematode are among the most important problems in tomato production. Tomato varieties with resistance to the most common species of root-knot nematodes (M. incognita, M. arenaria and M. javanica) have been released in the past, but these cultivars often lack resistance to other nematode species like M. enterolobii and M. haplanaria and to southern blight disease. Heirloom cultivars are particularly sensitive.
Southern blight, caused by the fungus Athelia rolfsii, is a necrotrophic pathogen commonly found in many areas of the southeastern United States. Tomato plants infected with A. rolfsii wilt permanently in soil with a high level of pathogen inoculum, resulting in significant economic losses to growers.
Roadster tomato grafted onto the rootstock Solanum sisymbriifolium (left) and non-grafted tomato (right) in the field are infested with southern blight. More than 80 percent of the non-grafted plants were dead by the end of the growing season.
ROOTSTOCK TO THE RESCUE
Grafting onto rootstocks resistant to southern blight can reduce the disease incidence and increase yield. Currently, the Maxifort rootstock, which carries resistance to southern blight, is commercially available. It also contains the Mi-1 gene that confers moderate resistance to species of M. incognita, M. arenaria and M. javanica.
In UGA greenhouse studies, S. sisymbriifolium was challenged with M. incognita, M. arenaria, M. haplanaria and M. enterolobii. Results showed that it confers a high level of resistance to all four root-knot species. These results were also confirmed in microplot and field experiments using M. incognita species. The data suggest the importance of using S. sisymbriifolium as a resistant rootstock for effective management of these devastating nematodes in infested tomato fields.
However, since grafted tomatoes are more expensive than non-grafted ones, growers will probably want to use rootstocks with resistance to multiple pathogens to minimize the production costs associated with application of multiple pesticides. Using a field study conducted in the summer of 2020, S. sisymbriifolium rootstock was found to be resistant to A. rolfsii. Field plots grown with tomato grafted on therootstock had significantly fewer dead plants compared to plots transplanted with non-grafted tomatoes.
The next step in the research studies will be to evaluate the combined use of grafting and nematicides and/or fungicides to manage effectively both root-knot nematode and southern blight in tomato. Efforts will also include a cost-return analysis of the control practices developed in this project to compare with growers’ practices for disease management.
Stink bugs are a diverse species that can wreak havoc on Florida’s tomato crop. With a piercing-sucking mouthpart, stink bugs pierce the fruit and suck out fluids. They also secrete enzymes while doing so, which damages the cells right under the skin of the fruit. This leads to little spots forming all over the fruit.
Picture submitted by Craig Frey/Shows a brown stink bug.
It is more visible once the fruit ripens, but packinghouses can identify it on green fruit as well. Ultimately, the fruit is unmarketable for producers to sell.
But for farmers, it is important to identify what stink bug species are on their crop. Some are predators, others are minor pests, while a few can cause major economic loss. Life cycles in tomatoes can range from five to 10 weeks, which is another important reason for proper identification.
“If it’s a 5-week life cycle versus a 10-week life cycle, a producer will have to spray twice as a frequently. It’s therefore critically important to know what species it is so we can know what their life cycle is and make sure our management fits accordingly,” said Craig Frey, University of Florida/IFAS Hendry County Extension Director.
Two Most Problematic Species
The two species tomato producers must contend with the most are the brown stink bug, Euschistus servus, and southern green stink bug, Nezara viridula.
“It was interesting to see that what I found in my master’s research in 2016-2017 correlated with what Dr. Amanda Hodges has seen in her traps over the last couple of years of surveying. There appears to be higher numbers of those two species than anything else,” Frey said.
Proper identification is key, but it is also essential to start management early and avoid playing catch-up.
Frey said stink bugs are more of an issue for grape tomatoes. Producers harvest them more frequently, and due to the required intervals between pesticide application and harvest, it is harder to find time to make an appropriate chemical application and keep the pest in check.
University of Florida/IFAS reminds tomato producers that plants must be destroyed within five days following final harvest of their crop. Under Florida law, abandoned tomato fields that have not been destroyed within five days after final harvest are subject to an Immediate Final Order per Rule, says Gene McAvoy, UF/IFAS Extension agent emeritus.
If tomato plants are left in the field, they could attract viruses and pests, including whiteflies. This could be problematic for neighboring fields or for future crops in the tomato field.
“Most growers are pretty good about it. They plant successive plantings, and you end up shooting yourself in the foot if you don’t clean them up pretty quickly. Most guys do, but occasionally you get a bad actor, maybe they’re leasing land and season’s not going good for them, for whatever reason, they walk away and leave it there,” McAvoy said.
“It just becomes a festering sore. We’ve seen problems with whiteflies. We’ve seen problems with virus. We’ve seen problems in seasons where we have late blight.”
McAvoy said growers in south Florida will plant every couple of weeks, starting in August. This provides a continuous supply of tomatoes to satisfy market demands. That means farmers may be harvesting non-stop from late October to early May.
Turn up the heat, and get more nutrition from your tomato, University of Florida researchers say. Furthermore, when you buy a tomato, it will be about as red as it can be, thanks to the UF/IFAS methods deployed for the study.
The findings are crucial to an industry in which Florida ranks second to California in tomato production in the United States.
In new research led by horticultural sciences Professor Jeffrey Brecht, UF/IFAS scientists put tomatoes in hot water and found it increased the red ripe look we love in tomatoes. By doing this, they also increased phenolics and carotenoids. To be clear, packinghouses in many states already treat tomatoes with hot water before shipping them to supermarkets – to clean them and prevent possible diseases — but the heat treatment for this study was a bit more extreme.
“The idea is that tomatoes have a certain genetic potential for antioxidant production that isn’t always realized,” said Brecht, a postharvest biologist. “That’s because tomatoes — all plants actually — produce antioxidants to deal with stress, and they produce more antioxidants the more stress they experience. Because we basically coddle tomatoes, the fruit doesn’t always realize its genetic potential for antioxidant production.”
“You could say that we found a way to make tomatoes get as red as they are able to get,” he said. “But the overall increase in antioxidants and the accompanying improvement in nutritional value is more important. Both the improved color and the improved nutritional value are benefits for consumers.”
For the study, researchers with UF/IFAS and the Agricultural Research Service (part of the USDA) applied increased heat to stimulate tomatoes. The major types of antioxidants in tomatoes are carotenoids and phenolics, Brecht said. Carotenoids include pigments, one of which is the red pigment, lycopene, which makes tomatoes red.
“So, in encouraging the tomatoes to make more antioxidants, we gave them a more red pigment,” he said. “But the major response to the heat stress was the production of phenolics, which are powerful antioxidants, but they are usually colorless.”
Researchers used an assay (test) that measures antioxidant capacity, but they also measured different types of antioxidant compounds to reach their conclusions.
Brecht describes the concept as “basic tomato physiology,” so the study’s methods apply to tomatoes, not just in Florida, but across the United States.
Tomatoes in Florida are most commonly harvested at the mature green stage and ripened after packing. Here’s how tomato packinghouses in Florida treat tomatoes before they go to your supermarket. They heat the dump tank water into which the tomatoes are transferred from field bins or gondolas to about 10 degrees above the tomato pulp temperature.
Packers use a water dump because it is the gentlest way to transfer fruit onto a packing line, and they use warm water because it reduces the chances of decay. Tomatoes are typically in the dump tank for a couple of minutes, Brecht said.
“We think that process could be modified to duplicate our hot-water treatment and improve the tomato quality,” he said.
Blossom-end rot, which manifests in the first few weeks of growth after tomato flowers are pollinated, causes black, rotted areas on the blossom end of the fruit, opposite the stem.
By Maria M. Lameiras for UGA CAES News
Home gardeners and commercial farmers alike can attest to the disappointment of seeing a beautiful tomato ripening on a vine, only to discover that the fruit has dark, sunken pits at the blossom end of the fruit. Called blossom-end rot (BER), this physiological disorder is prevalent in fruit and vegetable crops, including tomatoes, and can cause severe economic losses.
Through a $475,000 grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture (USDA-NIFA), University of Georgia researchers are looking for the genetic and developmental factors of BER with goals of investigating causal mechanisms and developing prevention and mitigation strategies for the disorder.
Research Specifics
Led by Savithri Nambeesan, an assistant research scientist specializing in ripening and postharvest physiology in the UGA Department of Horticulture at the College of Agricultural and Environmental Sciences (CAES), the study will compare the genetic traits of tomato lines that are susceptible and resistant to BER through genetic mapping to try to identify the regions in the genome that cause BER. It will also examine developmental and molecular contributors to the disorder.
“If we can find the factors that lead to BER, we can use that information to tailor management practices to minimize the disorder,” said Nambeesan, who is working on the project with horticulture professor and plant geneticist Esther van der Knaap, who has done extensive work on tracing tomato genomes.
Tomato Crop’s Value
The U.S. tomato crop was valued at more than $1.6 billion in 2019. In severe cases, BER can cause crop losses of up to 50% of the total yield in affected fields, resulting in a significant economic loss.
Nambeesan said the disorder, which manifests in the first few weeks of growth after tomato flowers are pollinated, is influenced by genetic, developmental and environmental factors. The study will combine molecular and developmental approaches to understand potential causes.
“Currently, the underlying cause of BER is thought to be due to calcium deficiency, but current field management strategies to correct that via irrigation and calcium fertigation have met with limited success. Generating more basic information on this disorder will help with breeding cultivars that are BER-resistant or provide more tailored management strategies to minimize this disorder,” she said.
“We will determine if BER can occur in fruits that grow relatively fast during their development and therefore have higher demand for calcium. Fruit receive their calcium through vascular tissues such as xylem, and therefore investigating how the xylem develops during fruit development may be critical in understanding calcium translocation into the fruit.”
MultiModel Approach
The multimodel approach to finding the underlying cause of BER in tomatoes will be useful in translating the information to other crops including vegetables and fruits such as pepper, watermelon, squash and eggplant. Because there are greater genetic and genomic resources available in tomatoes, it is the best model system for research that can translate into knowledge applicable to other crops.
“If we can tackle the problem using two approaches in molecular physiology — how fruit growth rates and xylem development tie into subcellular calcium localization — we can find the causative factors for it and we can address it more effectively,” she said. “We also are taking a two-pronged genetic approach, identifying certain loci that are involved in blossom end rot and finding genes in the genome to develop lines that are resistant.”
Root-knot nematodes (Meloidogyne spp.) are one of the most rapidly spreading of all pests and pathogens. The southeastern United States (Florida, in particular) is a paradise for these parasites. Nematodes cause damage to vegetables all over the world, and anyone who has had to deal with root-knot nematodes knows how difficult they are to control.
Root-knot nematode damage is often not recognized and is frequently confused with other biotic or abiotic problems, such as disease, nutritional and watering issues. When nematode populations are high and weather and soil conditions are favorable, root-knot nematode damage can become so bad that total crop loss occurs. This is especially the case when soils are already warm at planting or when a double crop is planted on the same bed.
Soil fumigants like Telone-chloropicrin mixtures and metam-based products like K-Pam are the most effective products when nematode pressure is high. Deep-shank (18-inch) injections of Telone can provide additional control in problematic fields by targeting nematodes that hide in the subsoil. Fumigants must be applied at least three weeks before planting to avoid phytotoxicity to the crop.
NEW NEMATICIDES
In the past, when beds were not fumigated, nematicide options for vegetable growers were limited to Vydate (oxamyl) and a few biological products. Over the past years, two new nematicides, Nimitz and Velum, have become available for vegetable growers in the Southeast. The new nematicides are less toxic and have a safer label (caution instead of danger) than previous products. They can easily be applied through drip irrigation systems. These nematicides should not be considered fumigant replacements, as they will target only nematodes. Additional measures need to be taken to manage soil diseases and weeds.
Nimitz should be applied seven days before planting to reduce the risk of phytotoxicity to the crop, while Velum can be applied before and after planting. Fluopyram, the active ingredient in Velum, is the same as in the fungicide Luna, although no clear evidence of soil disease control was observed for Velum in University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) experiments. Care should be taken not to exceed the maximum annual use rate of fluopyram when using both Luna and Velum.
Both Nimitz and Velum have been extensively tested at the UF/IFAS Gulf Coast Research and Education (GCREC) farm and are currently being evaluated in commercial fields. Their performance against root-knot nematodes on a variety of vegetables such as tomato, cucumber, squash, cantaloupe and watermelon was generally good and comparable to Vydate. Unless nematode pressure is too high, these products are a good alternative for growers that cannot or do not fumigate, or they may provide additional nematode control after fumigation when nematode pressure is high or long-season control is required.
ORGANIC OPTIONS
For organic growers, several biological products are available. They can be toxins derived from plants, bacteria or fungi while others are biocontrol organisms such as several species of bacteria and fungi. Some product names are ProMax, Kyte Gold, Ecozin, Dazitol, Majestene, DiTera and MeloCon. Typically, organic nematicides require multiple applications. In conventional production, they can be used as part of a program with chemical nematicides. Research into organic nematicides’ potential is ongoing at the GCREC and will be reported in future updates.
Root-knot nematode damage on tomato
Cover crops can also be good options to include in a nematode management plan. Summer cover crops like sunn hemp and sorghum-sudan grass can help reduce populations of most species of root-knot nematodes. The most common species in the Southeast are the southern (M. incognita), Javanese (M. javanica) and peanut (M. arenaria) root-knot nematodes. Often, vegetable fields will harbor more than one of these species. However, many more species exist.
In Florida, more than 15 root-knot nematode species have been found, including seven in vegetables. One particularly virulent and aggressive species is the guava root-knot nematode (M. enterolobii). This nematode has become a serious concern for the sweet potato industry in the Southeast and can cause severe damage to almost all vegetables grown in the region.
RESISTANT CULTIVARS
Vegetable growers that fumigate may not care much what species of root-knot nematode they have in their field as fumigants probably kill all species equally. However, knowing your root-knot species does matter when cover crops or nematode-resistant tomatoes are part of the nematode management plan. Research at the GCREC has shown that while some cover crops, like cowpeas, may be poor hosts to certain species of root-knot nematodes, they may be good hosts to other species.
Also, when root-knot nematode-resistant tomato cultivars are used, it is important to realize that while these cultivars are resistant to the three most common species mentioned above, they are not resistant to other root-knot species (including guava root-knot). Nematode-resistant tomato cultivars performed very well in root-knot nematode infested fields in recent trials in Florida. Root gall damage was negligible, and yields were increased compared to a susceptible cultivar. Fears, based on earlier reports that the nematode resistance gene in these cultivars might break down in the warm soils of Florida, were unjustified in GCREC trials.
The resistant cultivars also greatly reduced nematode reproduction and root-knot soil numbers by the end of the crop. This is often not the case when only a fumigant is used, as the fumigant will protect the crop from early nematode damage and yield loss, but nematode populations often increase by the end of the crop. Nematode-resistant cultivars are the easiest and cheapest method to manage root-knot nematodes, but unfortunately nematode resistance is rarely a priority in tomato and vegetable breeding programs.
Florida-grown tomatoes – particularly the UF/IFAS-bred Garden Gem – pack a tasty punch for tomato juice, new University of Florida research shows.
By and large, the biggest market for Florida tomatoes remains food services. They’re not generally harvested for processed products, such as juice, paste and more. But they’re still fresh, whole tomatoes.
For years, researchers have toiled to help breeders develop the genetic traits to give UF/IFAS-bred tomatoes more flavor.
Now, for a newly published study, scientists used six UF/IFAS varieties to process into six different tomato juices. In three testing panels comprising a total of 255 consumers, researchers asked the testers at the UF Sensory Lab how they tasted and smelled. The verdict: two “thumbs-up.” While other varieties fared well in the tests, panelists consistently rated juice made from the Garden Gem significantly higher for aroma, flavor and texture.
“I think this study shows that Florida tomatoes are viable for making processed tomato products,” said Paul Sarnoski, a UF/IFAS associate professor of food science and human nutrition. “Our juice exhibited better flavor – with more fresh and fruity attributes closer to that of a fresh-picked tomato.”
Better Tasting Tomatoes Lead to Improved Tomato Juice Flavors
Sarnoski, lead author of the new paper that summarizes the research, said better-tasting tomatoes lead to improved tomato juice flavors. So, it behooves tomato growers to produce tomatoes that go beyond the bland flavors of the past and deliver tasty products to consumers.
Sam Hutton, a UF/IFAS associate professor of horticultural sciences and tomato breeder at the Gulf Coast Research and Education Center, believes the new data on tomato juice will help his efforts to develop tastier tomatoes for farmers to grow.
“This research is interesting to me because the chemistry of better-tasting juice is very similar to the chemistry of better-tasting tomatoes,” Hutton said. “So, these results help to direct my program’s efforts to develop varieties with improved flavor, especially ones with more of these fruity attributes. Such varieties may then be more preferred by consumers and could help boost demand and consumption of Florida tomatoes.”
Better Marketing Opportunity?
Now that researchers know Florida-grown tomatoes are good for tomato juice, scientists want to know whether Florida tomatoes can be marketed at a cost-effective price. Once they clear those hurdles, scientists hope to help producers stock grocery stores with Florida-grown tomato products. Generally, processed tomatoes are sold for less money than fresh-market ones and need to be processed into a juice, sauce, paste and so forth, Sarnoski said.
Toward that end, scientists need to find out whether — working with farmers — they can produce tomatoes at a cost that’s competitive with other regions. They also need to know whether Florida has the food-processing infrastructure in place. If not, does the industry need to adapt existing food processing infrastructure to produce processed tomato products?
“I think these two questions relating to costs need to be answered before juice from Florida processed tomato products end up in a supermarket,” Sarnoski said. “Right now, in Florida, most of the juice processing is focused toward citrus. Perhaps some of that infrastructure can be modified to make tomato juice.”
