The Clemson University's Edisto Research and Education Center in 2023 is focusing on a number of innovative research projects, one of which is the inoculation of watermelons against one of its most aggressive diseases.
"Fusarium wilt is one of the most destructive diseases of watermelon which can cause substantial if not total yield loss in a field of watermelons," Edisto Research and Education Center Extension Vegetable Specialist Gilbert Miller said. "Currently the management recommendations for control of fusarium wilt are limited."
The Blackville-based EREC is proposing to utilize an Arbuscular mycorrhizal fungi (AMF) for its potential to improve the watermelon’s ability to fight off fusarium wilt.
"The beneficial AMF forms a symbiotic relationship with the host watermelon plant and aids the plant in acquiring water and nutrients," Miller said. "More importantly it also reduces the ability of the fusarium wilt organism to infect the watermelon plant. The beneficial AMF can boost the plant immune system much like vaccination in humans."
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Miller said AMF will be used at the EREC this year.
"When we plant seedless watermelon seed in the greenhouse, we will be inoculating the seed with AMF," Miller said. "The AMF will colonize the transplant root system while in the greenhouse, and when transplanted to the field will continue to colonize the growing watermelon root system."
"We will be testing this potential method of fusarium wilt control in a farmer’s field which had 100% loss of their watermelon crop due to fusarium wilt in 2022," Miller said.
Miller said regardless of crop rotation, once a field is infected with fusarium, the organism will remain in the field indefinitely and continue to infect subsequent watermelon crops.
"There are no watermelon varieties resistant to all the strains of fusarium wilt," Miller said. "Grafted watermelons with a root stock resistant to fusarium have shown promise but the cost of the seedlings is four to five times the cost of regular watermelon transplants."
Chickpea production
The EREC began a multiyear study of chickpea production in 2022 to see if the crop could be a potential for South Carolina farmers.
"We learned a couple of valuable lessons the first year of production," Miller said. "Chickpeas are legumes and must be inoculated with a specific Rhizobium bacterium for the plant to acquire the much-needed nutrient nitrogen."
"Limited to no inoculation in 2022 resulted in very poor plant growth and subsequent unsatisfactory pod production," Miller continued. "We will be using a granular soil Rhizobium inoculant for chickpea production in 2023."
Miller said chickpeas prefer cold weather and are tolerant to frost, meaning yields are best when planted in late winter.
"Harvest should be completed sometime in May prior to consistent warm/hot weather," Miller said.
There are challenges related to chickpea growth.
"Winter weeds such as wild radish can overwhelm the chickpea crop," Miller said. "This occurred in our chickpea crop in 2022."
"Due to the narrow row planting of chickpeas, manual cultivation is difficult," Miller continued. "Consequently, we will be looking at different herbicides which will control wild radish and other problematic winter weeds."
Chickpeas are an annual grain legume, or “pulse crop,” that originated in what is now southeastern Turkey and Syria and were domesticated about 9,000 B.C., Miller said.
Most U.S. production is in California and the Pacific Northwest.
In the U.S., chickpeas commonly are used fresh in salads and hummus, and cooked in stews and curry.
ASD watermelon trials
The EREC is studying anaerobic soil disinfestation through the incorporation of four different organic materials: cotton seed meal; broiler litter with molasses; chopped up rutabaga and cabbage; and chopped up rutabaga, cabbage and rice hulls.
The ASD materials were applied, and incorporated Feb. 16; plastic mulch and drip irrigation were applied, and a saturating irrigation program was begun, Miller said.
"Soil sensors were installed, which will monitor soil temperature, soil oxygen levels, and production of volatile organic compounds," Miller said. "The ASD process will take up to six weeks. When conditions are suitable, which we anticipate will be early April, watermelon transplants will be planted."
Soil-borne diseases, nematodes and troublesome weeds such as nutsedge are problematic in intensive vegetable production, Miller said.
"ASD is a process which has shown to be effective against a wide range of soil-borne pathogens, including bacteria, fungi, nematodes and some weed seed," Miller said.
Miller explained that ASD is a three-step process in which soil is amended with a carbon source, irrigated to saturation and covered with plastic mulch for several weeks.
"During the ASD process, beneficial soil microbes break down the added carbon source, deplete oxygen in the soil and produce toxic byproducts that kill soil-borne pathogens," Miller said. "Various organic materials and agricultural byproducts have been shown to be effective soil amendments for ASD."
Pumpkin Variety Trial
The EREC we will be evaluating 40 pumpkin varieties for production in South Carolina. It is the ninth year the research center has conducted the trial.
The pumpkin varieties vary from small to large, ornamental and edible. The trial is being done in cooperation with the New Zealand Hybrid Seed Company.
"Although we have yet to determine a suitable Jack O Lantern or carving pumpkin variety which will consistently produce in the eastern part of South Carolina, we have determined several small and ornamental pumpkins suitable for planting in the Southeast U.S.," Miller said. "Some of the varieties we have tested and have shown to be suitable for production in South Carolina are included in the new Pumpkin Guide found at: https://www.clemson.edu/cafls/research/edisto/sth_pumpkin_guide23.pdf
Sweet potato trial
The EREC will begin the second year of a sweet potato variety trial with drip irrigation.
"Sweet potatoes are typically grown without irrigation, either overhead or drip," Miller said. "We incorporated the use of daily drip irrigation with sweet potato production in 2022 and will do so again in 2023."
"Preliminary results indicate an earlier maturing sweet potato crop with a higher percentage of select or #1 grade sweet potato roots with drip irrigation compared to no irrigation," Miller said. "We will continue this research for a third year in 2024 and then compile an economic analysis of sweet potato production with and without drip irrigation."
Watermelon Field Day
The EREC Watermelon Field Day is scheduled for Thursday, July 13.
Registration and the indoor sessions will begin at 8 a.m.
At 10 a.m., a field trip will be held to view and discuss research plots.
Participants will be able to view and taste more than 50 watermelon varieties.
There will be seedless, mini seedless and heirloom seeded varieties available.
More details will be published closer to the event time.