Cause Phytophthora capsici, a fungus-like microorganism that lives in soil. It causes root rot in pepper and eggplant and is most active in moist, warm weather (75°F to 91°F). Disease is generally seen in the wettest areas of a field.
Symptoms Dark-gray to dark-brown, water-soaked spots develop on roots and stems, causing plants to wilt and die. Leaf spots develop, which are initially gray-to-brown in color, water soaked in appearance, and irregularly shaped, later becoming light brown. Fruit show similar spots, often enlarging to cover the entire fruit, which later dries and mummifies. Whitish sporulation may develop on infected fruit.
Cultural control
- Plant in well-drained fields.
- Practice light irrigation to help prevent overly wet soil; sub-surface drip irrigation can help to the soil surface dry and minimize disease development.
Chemical control
- Phosphorous acid-based products (Group P7) are labeled for use and are very effective.
- Fosphite at 1 to 3 quarts/A on 14- to 21-day intervals. See label for interval time requirement with copper-based products. May be applied up to the day of harvest. 4-hr reentry.
- Fungi-phite at 1 to 2.5 quarts/A on 7- to 10-day intervals. See label for interval time requirement with copper-based products. 4-hr reentry.
- Rampart at 1 to 3 quarts/A on 14- to 28-day intervals. See label for interval time requirement with copper-based products. May be applied up to the day of harvest. 4-hr reentry.
- Mefenoxam (Group 4) formulations are available and are labeled for disease suppression.
- MetaStar 2E AG at 4 to 8 pints/A as a preplant or at planting treatment. Do not apply within 7 days of harvest. 48-hr reentry.
- Ridomil Gold SL at 1 pint/A preplant incorporated in top 2 inches of soil or as a soil spray. 48-hr reentry
- Omega (Group 29) at 1 to 1.5 pints/A on a 7- to 14-day interval; initial application may be made as a soil drench at transplanting at 1.5 pints/A. Preharvest interval is 30 days. 12-hr reentry.
- Orondis Gold (Group 49 + 4) at 28 to 55 fl oz/A as an in-furrow, transplant water or banded soil application at planting. May be applied through drip after emergence. Preharvest interval is 7 days. 48-hr reentry.
- Orondis Gold 200 (Group 49) at 4.8 to 9.6 fl oz/A at planting, in-furrow or by drip. Do not apply more than two (2) sequential applications. Preharvest interval is 0 day. 4-hr reentry.
- Presidio (Group 43) at 3 to 4 fl oz/A on 10-day intervals in combination with another fungicide that has a different mode of action. Preharvest interval is 2 days. 12-hr reentry
- V-10208 (Group 22) at 8 fl oz/A on 7- to 14-day intervals. Do not make more than one (1) application before alternating to a fungicide in different FRAC groups (non-Group 22). Preharvest interval is 2 days. 12-hr reentry.
- 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.
- Zampro (Group 40 + 45) at 14 fl oz/A for no more than three (3) application per season. Do not apply more than two (2) applications before alternating to a fungicide with a different mode of action. Preharvest interval is 4 days. 12-hr reentry.
Biological control
- Bexfond at 7 to 28 fl oz/A. O
- Double Nickel LC at 0.5 to 4.5 pints/A for soil application on 14- to 28-day intervals. Can be applied the day of harvest. 4-hr reentry. O
- Stargus at 2 to 4 quarts/A plus a nonionic surfactant on 7- to 10-day intervals. Preharvest interval is 0 days. 4-hr reentry. O
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.