Skip to main content

Phytophthora Blight and Its Management in Cucurbit Crops and Other Vegetables

 phytophthora ravgaged pumpkin

Updated July, 2020.

Phytophthora blight is one of the more destructive diseases of vegetable crops. Most cucurbit crops and pepper are very susceptible. Cantaloupe is less commonly affected than other cucurbits. Eggplant, tomato, snap bean, and lima bean are also susceptible. Snap bean is the most recently identified host for the pathogen.

Symptoms include crown rot, stem and vine lesions, tip blight, leaf spots, lesions on petioles, root rot, and fruit rot. Type of symptoms that occur vary among crops. Fruit rot is typically the only symptom with cantaloupe, cucumber and tomato.

View symptoms in several crops at the LIHREC website:

The pathogen causing Phytophthora blight, Phytophthora capsici, is thought to move into a field primarily in contaminated water or soil moved from an affected field. It can infect seed. This pathogen can survive in a field for many years in the absence of a host crop as oospores or by infecting roots of weeds including purslane, thus it is difficult to manage through rotation.

Recommended management program includes cultural practices combined with fungicides. It is considered key to minimize opportunity for there to be standing water in a field after rain or irrigation as this provides ideal conditions for blight to develop. A preventive fungicide program is recommended.

Detailed information about Phytophthora blight and its management are in the following articles and tables:

More information/prepared by:

Margaret Tuttle McGrath
Associate Professor
Long Island Horticultural Research and Extension Center (LIHREC)
Plant Pathology and Plant-Microbe Biology Section
School of Integrative Plant Science
College of Agriculture and Life Sciences
Cornell University

© 2020 Cornell University. This web resource is designed to enhance access to Cornell's vegetable production resources. This site is a project of the Cornell Vegetable Program Work Team (PWT). Visit the About section for more information on the team. Comments or questions? Email Craig Cramer, Communication Specialist, School of Integrative Plant Science. Some of the informational links provided are not maintained by, nor are the responsibility of, Cornell Cooperative Extension and Cornell University. Mention of commercial products and trade names is for educational and informational purposes only. Manufacturers' instructions change. Read the manufacturers' instructions on the pesticide label carefully before use. Inclusion of information is not intended as an endorsement by Cornell Cooperative Extension or Cornell University, nor is discrimination of excluded information implied. Cornell University is an equal opportunity, affirmative action educator and employer. If you have a disability and are having trouble accessing information on this website or need materials in an alternate format, contact for assistance.
Skip to toolbar