Phytophthora can cause a seedling disease and it can also cause a root rot later in the season. Seedling infection may result in seed rot or seedling death. Later infection results in root rot, a sudden wilt and a dark line that proceeds up the stem as far as the second or third node. Several races of Phytophthora are present in the area, but race 3 is the most common. Certain varieties have resistance to race 3 and some other races.
Resistance is effective in both the seedling and the mature plant.
Aphanomyces Seedling Disease and Root Rot of Sugarbeet. As with Phytophthora, recent soil temperatures have been too cool for optimum infection, but a couple of warm sunny days could change that. Infection in the seedling stage may result in seedling death or unthrifty seedlings with black root tips. Later infection may result in plants that are greenish-yellow and wilt at midday. Infected plants have very little tap root.