Phytophthora capsici:
In squash fields, Phytophthora capsici causes wilting, crown, root, and fruit rot, plant stunting and death. Since the disease results in a range of symptoms in squash it is often referred to as Phytophthora blight. Sporangia are formed on infected fruit and have a powdered sugar appearance. P. capsici is favored by rain and warm temperatures, and in the presence of water sporangia can differentiate into swimming zoospores. Water management has a high impact on disease development and surface irrigation water can be a source of zoospore spread. The pathogen has two mating types, A1 and A2, that form a survival thick-walled structure called the oospore when they come into contact. The oospore can overwinter in the soil and persist in infested soil for as long as 10 years. Watermelon and cucumber vines are typically less susceptible to P. capsici than squash. However, all fruits are highly susceptible, especially if they are in direct contact with soil.
Diagnostic Resources
- A Diagnostic Guide for Phytophthora capsici Infecting Vegetable Crops
by: Camilo H. Parada-Rojas, Leah L. Granke, Rachel P. Naegele, Zachariah Hansen, Mary K. Hausbeck, Chandrasekar S. Kousik, Margaret T. McGrath, Christine D. Smart, and Lina M. Quesada-Ocampo
Plant Health Progress (2021) Vol. 22, No. 3 - Summer Squash Disease Key
- Winter Squash Disease Key
- Pumpkin & Gourd Disease Key
- MyIPM for Vegetables – An App developed by the Southeastern Vegetable Extension Workers
- Plant Disease Clinics
Disease Control Information
- Are your cucurbits infected with Phytophthora capsici? – Quesada Lab at NC State
- Managing Mildews and Phytophthora Blight Successfully in 2019 – Cornell Vegetables
- Phytophthora Blight – Smart Lab at Cornell Vegetables
Infección de Phytophthora (2017) - Phytophthora Blight and Its Management in Cucurbit Crops and Other Vegetables – Cornell Vegetables
- Phytophthora Blight on Cucurbit Crops: Photo Gallery – Cornell Vegetables
- Phytophthora Blight of Cucurbits – Cornell Vegetables
- Reduced tillage for Managing Phytophthora Blight and Other Soil-Borne Pathogens
- Phytophthora Blight in Cucurbit Crops – Cornell Vegetables
- Plant Pathology Disease Factsheets – Hausbeck Plant Pathology Research Lab at Michigan State University
Managing Phytophthora on Summer Squash and Zucchini
Manejo de Phytophthora en Calabaza de Verano y Calabacín
Managing Phytophthora on Winter Squash and Pumpkin
Manejo de Phytophthora en calabaza de invierno y en calabaza - Vegetable Diseases Caused by Phytophthora capsici in Florida (2018, 2021) UF/IFAS Electronic Data Information System
Plant Disease Management Reports
- Evaluation of hard squash cultivars for age-related resistance to fruit rot caused by Phytophthora capsici under laboratory conditions, 2019.
- Evaluation of fungicides to control Phytophthora fruit rot of winter squash, 2016.
- Evaluation of post-harvest fungicide dips for control of fruit rot of winter squash, 2016.
- Evaluation of fungicides to control Phytophthora fruit rot of winter squash, 2015.
- Evaluation of winter squash cultivars for resistance to Phytophthora root rot, 2015.
