HOMESTEAD, Fla. – A specialty pumpkin traditionally used in Caribbean, South and Central American dishes, has caught the eye of University of Florida scientist Geoffrey Meru.
Meru, a vegetable geneticist at the UF/IFAS Tropical Research and Education Center, is leading a multi-institutional project aimed at adding value to the calabaza commodity chain by eliminating barriers in seed and cropping systems, as well as laying a foundation for novel and lucrative products. The study will determine whether the calabaza provides the right combination of profit, wider consumer demand and usefulness for a variety of industries. Meru will look at the calabaza as the next pumpkin of choice for those who specialize in the brewing, food, agriculture, manufacturing and health industries.
“The calabaza is a nutritional powerhouse that is easy to grow almost pest free, and an excellent crop you can use in rotation with others,” said Meru. “Because it is adapted to Florida’s tropical climate with minimal irrigation requirements, we want to take a closer look for its desirable qualities as a sustainable Florida crop.”
With help from a two-year, nearly $400,000 U.S. Department of Agriculture grant, Meru will lead a team of UF/IFAS researchers in food science, human nutrition and community sciences.
They will study the risks and benefits of crop production, predict the market interest for consumption of the calabaza’s flesh and other lucrative products, determine the nutritional value of this specialty pumpkin, and develop conventional and organic-cropping systems that suppress weeds and improve soil. They’ll also determine the best cultivars for the Florida, Georgia and Puerto Rico markets.
The grant, in collaboration with the universities of Puerto Rico and Georgia, is aptly named “Specialty Pumpkin: Laying the Groundwork for an Emerging Crop and Lucrative Products.”
UGA CAES photo/Peyton Collins of Union County had the prize-winning pumpkin, weighing 548 pounds.
By Austin Clark for CAES News
More than 25 pumpkins were submitted to Georgia 4-H’s 2020 statewide pumpkin-growing contest, with the largest pumpkin, cultivated in north Georgia’s Union County, weighing in at a whopping 548 pounds.
All Georgia 4-H youth were encouraged to participate by submitting one pumpkin for consideration. Participants took their entries to their local University of Georgia Cooperative Extension office for weighing. This year, the Georgia Fruit and Vegetable Growers Association sponsored the contest, donating prize money of $100 for first place, $50 for second place and $25 for third place.
The winners of the 2020 Georgia 4-H Pumpkin Growing Contest are:
Peyton Collins, Union County, 548 pounds
Natalie Payne, Union County, 432 pounds
Ava Sharp, Union County, 316 pounds
Georgia 4-H empowers youth to become true leaders by developing necessary life skills, positive relationships and community awareness. As the largest youth leadership organization in the state, 4-H reaches more than 242,000 people annually through UGA Extension offices and 4-H facilities. For more information, visit georgia4h.org.
An abnormally wet September has required Alabama pumpkin farmers to maintain strict fungicide applications, especially following Hurricane Sally’s trek through the state on Sept. 16.
Neil Kelly, Alabama Extension Regional agent in Southeast Alabama, said the lack of consistent sunshine over the last two weeks has created disease concerns for pumpkin growers.
“We haven’t really had a real good break in the weather and things really haven’t dried out very much since Sally came through,” Kelly said. “It’s just been important that they stick to the spray schedule and try to make weekly fungicide applications and stick with it. We’ve carried out extra spraying more so than normal. We kind of back off on some of our fungicide sprays once people start to walk through the fields.
“We had sunny warm weather leading up to this event. We’ve been getting plenty of rain and of course we irrigate. The pumpkin crop was a little bit ahead of normal. They mature out a little quicker and the vines are starting to go downhill, and then we got this wet weather. It was important for people to stick with a fungicide spray program.”
Region of Responsibility
Kelly is responsible for the Southeast part of Alabama including Barbour County, Bullock County, Coffee County, Covington County, Crenshaw County, Dale County, Geneva County, Henry County, Houston County and Pike County. He attests that certain diseases become a factor if pumpkins are growing in fields with increased moisture.
Such diseases include phytophthora, fusarium and downy mildew.
“Plant diseases and certain fruit rots become more of an issue when the pumpkins stay wet for an extended period of time. (Sally) caused some issues but it was more from plant disease issues more so than flooding,” Kelly said.
“Obviously, if the weather does not dry out a little bit, the first of October when everybody gets started with the pumpkin patches and things like that, it’s going to create some issues getting in and out of the field.”
University of Georgia breeders developed the Orange Bulldog pumpkin.
By Cecilia McGregor and George Boyhan
Cucurbit crops are some of the most widely grown vegetable crops in the Southeast. However, the hot and humid climate is conducive to pest and disease development, which presents a challenge to growers. Cucurbit breeding at the University of Georgia (UGA) is focused on breeding pumpkin, watermelon and squash with excellent fruit quality and enhanced disease resistance.
PUMPKINS
Pumpkins are an important crop in the United States, particularly as decorations during the fall. Unfortunately, pumpkins are difficult to grow in the Southeast because of diseases. There are several diseases (particularly viruses) that affect traditional pumpkins. These diseases are transmitted by aphids in a non-persistent way. This means that as soon as the insect probes the tissue, the virus is transmitted. Control is difficult, because even with 90 to 95 percent insect control, the remaining 5 to 10 percent can effectively infect the crop.
UGA began a breeding program in 1996 with a collection of pumpkin seeds from Brazil. Seed from both elongated and flattened fruit of Cucurbita maxima were obtained and interplanted. Putative hybrids were collected. This began several years of selection for fruit with a round shape, pleasing color and open cavity. These pumpkins have a greater degree of virus resistance compared to traditional pumpkins (C. pepo), so they produce more consistently.
The resulting variety, Orange Bulldog, was released in 2006. Since there was no interest among seed companies, UGA has been handling sales. The primary audience for this variety is pick-your-own and roadside marketers. The vines hold up particularly well into the fall for direct marketers that “reseed” their pumpkin patch with new fruit each day.
Pumpkin research concentrated on developing disease resistance into commercially acceptable pumpkin lines has continued at UGA.
WATERMELON
UGA is also actively breeding for gummy stem blight and fusarium wilt resistance in watermelon. Resistance to gummy stem blight was first described in 1962 when it was discovered in a wild relative of watermelon, Citrullus amarus. This is the same species that was used to breed the fusarium-resistant, non-harvested SP pollinizer cultivars.
Breeding disease resistance into commercial, edible cultivars from this wild germplasm has proven difficult since the wild relative has hard, inedible flesh. This is further complicated by the fact that there are different species of the Stagonosporopsis pathogen that cause gummy stem blight and different races of Fusarium oxysporum var. niveum that cause fusarium wilt. The resistances to these diseases are quantitative, meaning that a single resistance gene does not give field-level resistance to the diseases. All these factors have delayed the development of cultivars resistant to these diseases.
Susceptible (left) and resistant (right) watermelon seedlings infected with gummy stem blight.
The breeding effort at UGA focuses on using modern selection methods to accelerate selection for resistance genes to speed up breeding efforts. Currently, selection is in progress for fusarium race 2 resistance and gummy stem blight resistance.
In addition to these disease-resistance breeding efforts, UGA breeds cultivars specifically for homeowners and farmers’ markets. The focus here is on novel traits like a variety of flesh colors and rind patterns and the egusi seed trait.
Egusi watermelon is very popular as an oilseed crop in many parts of Africa. The seeds are very high in oil (40 to 50 percent) and protein (25 percent) and are eaten as snacks or as a thickener in soups and stews. Egusi seed is large and flat with a unique fleshy outer layer that dries into a very thin seed coat that can easily be shelled. Traditional egusi watermelon has hard inedible flesh, which goes to waste. UGA is breeding egusi watermelon with edible flesh. These plants will produce fruit that pack the health benefits associated with the antioxidants in red- and orange-fleshed watermelon while also being a source of high oil and protein seed.
SUMMER SQUASH
In 2019, UGA started a squash breeding program. This program was launched in response to the severe yield losses experienced by Georgia growers in recent years due to whiteflies and whitefly-transmitted viruses.
The sweetpotato whitefly (Bemisia tabaci) can directly cause yield losses in many different crops due to feeding, but an even bigger cause of yield losses are the viruses it transmits. Sweetpotato whiteflies can transmit more than a hundred different viruses. Cucurbit leaf crumple virus (CuLCrV) and Cucurbit yellow stunting disorder virus (CYSDV) are some of the most important to squash growers.
Commercial squash cultivars have proven to be very susceptible to these viruses, and sources of resistance have not been identified. UGA, in collaboration with the University of Florida, has started large-scale evaluations of squash germplasm from all over the world in search of resistance. Several genotypes with resistance to CuLCrV and CYSDV were identified in 2019 and are now being evaluated further for use in the breeding program.
The UGA cucurbit breeding programs are committed to developing cultivars well adapted to the Southeast, with high disease resistance and exceptional fruit quality for both large- and small-scale growers in the region.
Growing pumpkins is popular in South Alabama, but it comes with its challenges. Neil Kelly, Alabama Regional Extension agent, said disease management is a huge concern for any grower interested in producing pumpkins.
“The pumpkin crop is a difficult crop to grow in my part of the state. I just throw that out to there to everybody that calls about growing pumpkins. Yes we can do it, but I’m going to tell you up front, it’s difficult and it’s not real consistent,” said Kelly, who serves 10 counties in the southeast part of the state, including Barbour County, Bullock County and Coffee County. “With the different mildews and things they can get, diseases are always an issue because we’re growing them during a time of the year when it’s warm and humid. That warm weather and hot weather and humid weather, coupled with the occasional summer shower and moisture, diseases are very difficult to control in pumpkins.”
Downy Mildew
Joe Kemble, Alabama Extension vegetable specialist, said pumpkin farmers need to be wary of downy mildew, which can be devastating on pumpkins. It requires conventional fungicides, but they must be applied before the disease develops. There are not any fungicides that are curative. He said downy mildew has been found in every county in Alabama.
“You’re going to have to spray your pumpkin crop for disease management on a very regular schedule much like we do watermelons and much like we do tomatoes. You’re going to have to stay on top of disease control in the pumpkins if you want to grow good, healthy pumpkin,” Kelly said.
Curing Pumpkins
Curing pumpkins can also be a problem. It is a process that involves elevating storage temperatures to 80 degrees F or 85 degrees F with 75% to 80% relative humidity for approximately 10 days. The curing process heals wounds, helps ripen immature fruit, enhances color and ensures a longer post-harvest life.
“The next problem that we have with pumpkins, if we get past all of the diseases and we produce a good pumpkin and we get past all of the insects…the next big problem we have with pumpkins in my part of the state is them curing out. When the pumpkin starts to ripen and they start to turn that nice bright orange color and they start to cure out, because of our high humidity and our high temperatures that time of year, a lot of times what you’ll see those pumpkins do is just get soft and start to rot instead of cure out like a gourd; like the typical hard-shelled pumpkin you see in the grocery store,” Kelly said.
Kelly said large pumpkin production areas like Arizona and New Mexico have low humidity, which leads to low disease pressure and pumpkins curing out really well.
“I would say the disease issue and curing are two of the biggest problems that we fight in pumpkin production and there’s really not a lot we can do about some of those. We can put out preventative stuff for the diseases and do the best that we can to head off any kind of issue but very few diseases do we have a curative spray for,” Kelly said.
The hint of fall in the air and the calendar turning to September means pumpkins are growing across Alabama. But producers need to be wary of certain diseases that can be detrimental to the pumpkin growing season, says Joe Kemble, Alabama Extension vegetable specialist.
“We do have a lot of pumpkins coming in. I was walking around a large patch (the other day). I would say, if you’re a pumpkin grower, with these frequent rain showers we’re getting, make sure you scout for downy mildew as well as anthracnose,” Kemble said. “Downy mildew can be devastating on pumpkins. It requires conventional fungicides, and the fungicides have to be out there to protect the crop before the disease develops. There really aren’t any fungicides that are curative.”
Cucurbit crops — like cucumbers, melons, squashes and pumpkins — are susceptible to downy mildew. The 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.
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.
“Downy mildew, I believe has been found in every county in Alabama. It’s devastating on cucurbits in general,” Kemble said. “It is a specific species on pumpkins. Just because you have it on your pumpkins doesn’t necessarily mean you’re going to have it on your cucumbers next to it. However, that’s a pretty good indicator that conditions are right for development of those diseases.”
