Phytophthora is probably not a top concern for most of you this time of year. We often think of the disease in seasons with too much rain. Despite the dry conditions in many areas, Phytophthora root and stem rot may be lurking in your soybeans.
Phytophthora is associated with moisture. Its occurrence is particularly favored by alternating wet and dry periods and is most common in poorly drained soils. Temperature also plays a roll and seems to like warmer conditions as opposed to cooler. The pictures below show stem discoloration and wilting leaves as Phytophthora infection girdles the stem. This variety has Rps1c resistance and a seed treatment was applied. Alternating (warm-wet / warm-dry) conditions occurred throughout June and July. Now is a great time to scout for late season Phytophthora and note the response of your soybeans.