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Stem canker

Area of impact: Stem

Description: Reddish brown sunken lesions appear at the base of branches or leaves and eventually develop into longer, dark brown cankers. Plant parts above these lesions can die. Inner stems may also turn brown. Leaves yellow and die and may remain attached after death. Tiny black dots appear on the stems of dead plants.

Pathogen involved: Diaporthe phaseolorum (a fungus)

Timing/Conditions: Occurs from mid-season to maturity after prolonged wet weather.

Contributing factors: Conservation tillage. Overwinters in infested soybean residue and can spread with seed.

Management practices: Plant resistant varieties, use foliar fungicides and delay planting. Tillage can also help.

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