Another symptom of Phytophthora is the seedling blight phase of the disease in which young seedlings that appear to be established turn off-color to yellow, wilt and die. The stems of these plants may show a brown discoloration that begins at the soil line and extends up the stem. The brown, dead leaves remain attached to the plant, and the dead seedlings remain evident in the field until the rows close. Phytophthora may also show up as plants begin to flower and set pod. Infected older plants show reduced vigor through the growing season or die gradually over the season. Lower leaves may show a yellowing between the veins or along the margins. Upper leaves may yellow. The stems show a characteristic brown discoloration that extends from below the soil line upward. Eventually the entire plant may wilt and die.

Phytophthora root rot is more severe in areas that are low or poorly drained, in compacted areas or in clay or heavy soils, but the disease can appear on plants growing in lighter soils or higher ground if the soil remains wet after planting. To reduce losses from Phytophthora select varieties with race-specific resistance, tolerance or a combination of race-specific resistance and tolerance; plant in good seedbed conditions; tile to improve drainage; prevent or reduce compaction; rotate crops and use an appropriate fungicide seed treatment.


click to enlarge click to enlarge