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Both Fusarium oxysporum and Fusarium solani cause seedling blight and root rot of soybean. These two fungi can persist in the soil, colonize various plant residues and survive as chlamydospores (fungal survival structures) or mycelium.
In fields with Fusarium seedling blight, stands may be uneven, there may be skips in the row and seedlings may be stunted and weak. The pathogens cause a brown to dark purple-brown or black rot of lateral roots, taproots and lower stems. The lower part of the taproot and the lateral root system may be rotted or destroyed. A proliferation of secondary roots may develop above the damage main taproot giving the plants a shallow, fibrous root system. The above-ground portions of infected plants may have an off-color to yellow cast. Foliage may dry and plants wilt or die during periods of drying winds or warm to hot weather. Crusting, hard pan layers, herbicide injury, deep planting, poor seed quality, hail damage, insect damage, mechanical injuries, poor fertility or other factors that delay germination and emergence favor the development of Fusarium seedling blight and root rot. To reduce losses from Fusarium seedling blight and root rot, plant good-quality seed with a good germination rate under good seedbed conditions, minimize or avoid stresses that delay germination and emergence and use an appropriate fungicide seed treatment. |
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