In Maine experiments, chisel plowing was more effective than moldboard plowing in reducing the incidence and severity of Fusarium stem lesions on potato. This was attributed to more rapid decomposition of infected residue after chisel plowing. Rotational crops also appeared to be important where residues of these crops were chisel plowed under. Fusarium root rot incidence was lower in potatoes following broccoli than in potatoes following oats, buckwheat, lupine, or peas. Oats increased Fusarium severity in subsequent potato crops when residues were turned under with a moldboard plow.
Gray mold develops on tomato under cool, wet conditions, especially when air circulation is poor.
Fungicides will not suppress an established infection, but offer some protection if used before infection occurs. If the weather turns warm or humidity drops below 90 percent, these lesions dry up and disease spread is restricted. When favorable blight conditions exist, however, a white spore-producing mildew appears on lower leaf surfaces at the outer edge of the lesion. Infection sources include infected seed stock, blighted tubers in cull piles, volunteer plants growing from infected tubers, and wind-blown spores. Spores develop on diseased plant parts and are splashed to other parts of the plant or other plants.