Fusarium-
Root Rot - Fusarium solani & other F. species
A problem on seedlings and young plant roots that develop in wet, cool soils, below 58ºF. Seedling growth can be slowed and plants usually are stunted and weak. Infection is often limited to lower taproots, and lower lateral roots which may be destroyed. New roots can develop from the upper taproot providing a shallow fibrous root system that is prone to fail in dry soils. The vascular system can be affected, turns brown or black, and this increases late season plant wilt under moisture limiting conditions. Stress from soybean cyst nematodes, or other nematodes, and DNA herbicides predispose plants to infection. These soil born-fungi survive as chlamydospores and as mycelium in plant residues. Fusarium solani, reported to be the cause of Sudden Death Syndrome (SDS), has been reported to be near Minnesota, but isolates of this “Blue Strain” from Minnesota soils have not been confirmed to be like the isolates from Iowa or Illinois. Symptoms of SDS are interveinal chlorosis, necrosis, and leaf defoliation. Petioles remain firmly attached. The central pith (when stems are split) should be white with no discoloration or decay. It is believed that certain isolates produce a toxin that translocates to the upper leaves.causing the above symptoms. Others report this fungus can be isolated from cyst nematodes.
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