number of cases of bacterial blight which occur). The number of samples collected in a particular state or region will correspond with the availability of sampling sites (i.e. Sampling will be conducted following boll formation but prior to defoliation and harvest. Project Methods Survey: Field surveys will be conducted in Georgia, Mississippi and Texas. If a new race of Xcm is found, it will be made available to cotton breeding programs. Changes in production practices, particularly regarding cultivar choice, will be monitored by the extension specialists via surveys as well as general state-wide bacterial blight problems. Tests will be conducted in the greenhouse on varieties that should be resistant and susceptible to bacterial blight, using other bacteria that are isolated in close proximity to Xcm.Extension specialists in Georgia, Mississippi and Texas will develop material for producers to manage this disease using IPM principles including current cultivars and their susceptibility to the disease, importance of plowing in infected plant material, and planting seed that is clean of the bacteria. There is an additional hypothesis, that the resurgence of the disease is due to an interaction between Xcm and another bacteria. These tests should provide evidence if a race shift is occurring. In addition, Xcm isolates from Texas will be tested on cotton cultivars differing in their disease response to race 18 of Xcm. The Xcm isolates collected in this project will be characterized for T3Es. Most pathogenic Xanthomonads deploy 10-30 distinct T3E proteins during infection, and on a population level, these T3E repertoires are variable. Xcm injects type 3 effector proteins (T3Es) into plants to promote susceptibility in cultivars. The project proposes to collect a diverse set of Xcm from Georgia, Mississippi, and Texas. It must be controlled for sustainable production of cotton. malvacearum (Xcm), is a yield limiting disease of cotton and also survives and spreads in seed. Bacterial blight, caused by Xanthomonas citri subsp. However, seeds usually do not show symptoms.Non Technical Summary This applied, research-led project addresses the resurgence of bacterial blight of cotton. Lesions can also occur on the pods causing the seeds to become shriveled and discolored. Generally young leaves are most susceptible to blight infection. Eventually the lesions will fall out of the leaf and the foliage will appear ragged. A yellowish-green "halo" will appear around the edge of water soaked tissue that surrounds the lesions. ![]() The centers of the spots will turn a dark reddish-brown and dry out. Symptoms in later growth stages include angular lesions, which begin as small yellow to brown spots on the leaves. Young plants may be stunted and if the infection reaches the growing point, they may die. ![]() Disease Symptomsīrown spots on the margins of the cotyledons characterize plants infected early in the growing season. Bacteria can also be spread to uninfected leaves when they rub against infected ones during cultivation, rain, and wind. Seedlings may be infected through infected seed.īacteria that enter the host produce a toxin, which prevents chlorophyll production. In order for infection to occur, the leaf surface must be wet. The bacteria enter the plants through stomata and wounds on leaves. Initial infection of soybeans occurs when wind or splashing water droplets from plant residue on the soil surface to the leaves carry bacterial cells. Bacterial blight ( Pseudomonas savastanoi) of soybeans is typically an early season disease, which over winters in the field on plant residue.
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