Symptoms and Signs
Foliar symptoms on plants with Fusarium crown and root rot include yellowing along the margin of the oldest leaves, followed by necrosis. Dry brown lesions develop in the cortex of the tap or main lateral roots. A necrotic lesion may also develop on the surface of the stem from the soil line to 4 to 12 inches above it. Internally, a reddish brown or chocolate brown discoloration extends no more than 6 to 12 inches above the soil line. Infected plants may be stunted and wilted, and older plants may die.
Comments on the Disease
Fusarium crown and root rot can occur in any of the California tomato-growing regions; in the Central Valley, it has recently become more common and widespread. The disease occasionally causes serious problems in greenhouses. In the field it causes economic damage in the Sacramento Valley, upper San Joaquin Valley, and near the coast, especially in Southern California. The fungus overwinters and survives for many years in the soil as spores. Long distance spread is by transplants and in soil on farm machinery. Spores are airborne in greenhouses. The disease is favored by cool soil temperatures. The host range of the pathogen includes some legumes, cucurbits, other solanaceous plants, and more.
In greenhouses, plant in steamed soil. In the field, planting disease-free transplants is the only recommended management practice for this disease.