![]() Gene expression analysis showed that expression of MELO3C010403-T2 but not MELO3C010403-T1 was significantly induced by D. The MELO3C010403 gene contains two alternative transcripts, MELO3C010403-T1 and MELO3C010403-T2, with five and seven nonsynonymous mutation sites, respectively. Ten putative genes were annotated in this region that contains a wall-associated receptor kinase (WAK) gene MELO3C010403. The Gsb-7(t) gene was finally delimited to a 140-kb interval on chromosome 7 using bulked segregant analysis and chromosome walking strategies. To further understand the resistance mechanism of H55R against GSB, an F 2 population was obtained from a cross between the GSB-susceptible line A15 and H55R, and genetic analysis indicated that the GSB resistance in H55R was controlled by a single dominant gene, tentatively named Gsb-7(t). In this study, 260 melon germplasm resources were screened for resistance to GSB, and an inbred line, H55R, that exhibited immunity to GSB was identified. Breeding GSB-resistant cultivars with host resistance genes is considered the most economic and effective strategy to control this disease. The Georgia Fruit and Vegetable Growers Association and the Georgia Watermelon Association have identified gummy stem blight as one of their top areas of concern for research and Extension efforts the last three years, McGregor said.Gummy stem blight (GSB), caused by Didymella bryoniae, is a devastating fungal disease of melon worldwide. If their plants are pathogen-free, they can spray fungicides a week or 10 days after planting instead of when the plants are put in the field.Īdditionally, once they’re developed, early detection methods can be applied by seed companies as diagnostic tools to reduce the distribution of infected seed. If the detection process is successful, growers will know whether their watermelon plants are infected with the disease. “The pathogen’s resistance to fungicides is a challenge for UGA Extension specialists, as we are running out of treatment options to recommend to growers.” “Gummy stem blight is one of the most important foliar diseases of watermelon that growers face every year,” Dutta said. “It would be important to detect the pathogen very early, before it can spread.”ĭutta, a UGA Cooperative Extension vegetable pathologist on the UGA Tifton campus, said farmers are especially concerned with gummy stem blight because of its emerging resistance to many fungicides that are used by watermelon producers. Since gummy stem blight can be seed-transmitted, it is not clear at this time what the best sampling method would be in greenhouses where the seed can potentially be the source of the pathogen,” said McGregor, a cucurbit breeder with the UGA College of Agricultural and Environmental Sciences. ![]() “For most pathogens where this type of detection has been carried out, spore traps were used to sample the pathogen. If infected seedlings can be detected early in transplant greenhouses using the LAMP assay, infected trays can be removed, preventing the spread of disease in the greenhouse. They plan to implement the loop-mediated isothermal amplification (LAMP) assay, or test, which is used to detect certain diseases in the greenhouse.ĭutta believes the LAMP assay is sensitive enough to detect low levels of pathogen populations. The team of UGA scientists are in the first year of a three-year, $93,000 study funded by the Georgia Department of Agriculture. The disease favors warm, wet conditions, much like south Georgia’s summer climate. Gummy stem blight causes lesions on leaves and stems and leads to defoliation. “Decreased use of fungicides is part of a long-term, sustainable and eco-friendly management strategy.” In addition, fungicide residues can have a potentially negative impact on soil and water organisms,” she said. “Current recommendations for control of gummy stem blight are nine fungicide applications per season, which translates into a $900 cost per acre per season. University of Georgia horticulturist Cecilia McGregor, along with fellow UGA scientists Marin Brewer and Bhabesh Dutta, studies the impact of reduced fungicide use through early detection of gummy stem blight in watermelons. Georgia watermelon growers who have a targeted, informed disease management plan for gummy stem blight disease could save money and lessen the environmental impact of producing this favorite summertime fruit.
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