By O. Neher and C. M. Ocamb
Cause The fungus-like soilborne organisms, Phytophthora drechsleri and Pythium aphanidermatum, cause root rot primarily in waterlogged soils at high temperatures. Low areas of the field are where these two diseases are most often found.
Symptoms Early in the infection, plants temporarily wilt but will recover overnight. With disease progression, wilt will become permanent. A brown-black wet rot begins on the lower taproot and progresses upward.
Cultural control
- Maintain good soil drainage.
- Do not over-irrigate.
Chemical control
- Warhammer (chitosan) at 4 to 12 fl oz/A on 7- to 14-day intervals. Studies at the University of Florida showed a reduction in disease severity for Phytophthora blight in squash when chitosan was applied as a 1% soil drench. No preharvest interval or reentry interval requirement.
Reference Mo, X., and Zhang, S. 2013. Effect of chitosan, Heads Up and TiO2 on Phytophthora blight in squash, 2012. Plant Disease Management Reports 7:V081.