![]() ![]() No other fungus will grow extensively in the soil (Figure 1). White fungal mycelium (thread-like strands) growing INTO the soil.Small tan to reddish brown sclerotia form at the base of the plant and/or in the soil around the plant.Diagnosis requires looking at the soil around the crown of the plant, in addition to the plant itself. You can distinguish southern blight in the field based on the following diagnostic traits, one or more of which may be present. Accurate diagnosis is critical to effective control. Severely affected plants can have vascular discoloration, which may be confused with Fusarium wilt. It can be easily confused with other crown rotting diseases, like Fusarium crown rot. Southern blight misdiagnosis is likely if it occurs in an area where it has not historically been an issue, like the Sacramento Valley. With a host range of over 500 plants, this fungus can easily persist from year to year in infected crop debris. Although this disease may initially only affect a few plants in the field, southern blight can be serious enough to cause significant yield loss within a season or two. Each infected plant can produce tens of thousands of sclerotia and then become more widely distributed in a field with each successive field operation. Southern blight survives in soil as hardened structures called sclerotia for at least five years. The fungus is favored by high temperatures (over 86☏), high soil moisture, dense canopies, and frequent irrigation. A list of resistant rootstocks is available on the tomato rootstock page at the Vegetable Grafting website.Southern blight, caused by the fungus Sclerotium rolfsii, is a destructive crown rot disease that rapidly kills tomato plants. The use of bacterial wilt resistant rootstocks has been used successfully in fields where bacterial wilt is prevalent or widespread. ![]() Note: It's unknown how much removal completely dimishes disease in the future if the pathogen has already spread to adjacent, non-symptomatic plants. Plants can be placed into a garbage bag or another container so as to not spread soil and bacteria to other plants. If bacterial wilt is present in a field, remove infected plants immediately. corn, rye, beans, cabbage) can reduce soilborne populations of the pathogen. Crop rotation and planting cover crops of non-susceptible plants (i.e. Cultural practices can provide some control of disease incidence. There are no chemical controls that provide effective control. Verticillium wilt typically causes V-shaped lesions on the leaflets and does not wilt as suddenly.ĭisease Management Skip to Disease Managementīacterial wilt can be very difficult to manage once present in the field. Fusarium wilt of tomato will typically have one-sided leaf yellowing or wilting. Small, tan to brown "bebe" sized round structures (sclerotia) are typically present. Southern blight on tomato will also wilt, but affected plants will have a crown rot with white strands or mycelium growing up the stem from the soil line. Look alike diseases: Bacterial wilt on tomato may be confused with other wilt or root rot diseases. Check out this video of bacterial streaming. The interior of the stem will be a light brown color in the pith area. A freshly cut stem at the base of the plant placed in water can also show a stream of a white slimy substance that is a strong indicator of the bacterium present in the vascular tissue. The plant eventually becomes permanently wilted and death occurs. This is due to less water needs in the morning when there is high humidity, but as the heat increases the clogged vascular system limits the water uptake and the plant wilts. Plants may appear wilted in the afternoon, seem to "recover" overnight only to wilt again in the afternoon. As the disease progresses, the base of the plant may show brown cankers, root rot, and a cross section of an infected stem may show a brown discoloration of the vascular tissue. Typically, plants affected by bacterial wilt will show wilting symptoms while the plant is still green and can appear to come on suddenly. Initial stages of the disease include a wilted appearance of the youngest leaves. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |