Phytophthora Diseases Affecting Fruiting Vegetables in WNC

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As the flooding recedes in western North Carolina, many growers are now reporting losses due to Phytophthora diseases on various vegetable crops including pepper, tomato, cucumber, and other cucurbits. Many vegetable fields were reported as flooded, and several were under water for some period of time. These conditions (flooding, standing water, and high amounts of rainfall) are conducive for Phytophthora diseases.

Phytophthora capsici causing bell pepper plants to wilt

Phytophthora capsici causing bell pepper plants to wilt

Phytophthora blight on cucumber

Phytophthora blight on cucumber

On pepper, cucumber, squash, and other cucurbits, Phytophthora capsici (Pcap) can cause root rot, stem and leaf lesions, and fruit rot. Symptoms include overall plant wilting, tan to brown lesions on leaves and stems, water-soaked or cleared lesions on the underside of the leaves, and rot on fruit that may have a fuzzy, whitish appearance, which is the spores of the pathogen.

Pumpkin field affected by Phytophthora root rot (P. capsici)

Pumpkin field affected by Phytophthora root rot (P. capsici)

On tomato, P. nicotianae (Pnic) and Pcap can cause leaf and stem lesions and fruit rot. Lesions caused by Pnic and Pcap resemble late blight (caused by P. infestans), but they are not the same disease. In fact, late blight has NOT been reported in NC as of June 5, 2018. Spores of Pnic and Pcap travel only locally (within a field) and by movement of infested soil, as opposed to late blight, which travels long distances by wind and air currents. Although the risk of spread to adjacent fields is lower for Pcap and Pnic, it is still very important to wash soil off of equipment that was used in an infested field to avoid spreading the disease to non-infested fields.

Phytophthora causing stem lesion and plant collapse on tomato

Phytophthora causing stem lesion and plant collapse on tomato

Lesions caused by Phytophthora nicotianae on tomato leaves.

Lesions caused by Phytophthora nicotianae on tomato leaves.

Lesions caused by Phytophthora capsici on tomato foliage

Lesions caused by Phytophthora capsici on tomato foliage

Late blight (Phytophthora infestans) on tomato foliage

Late blight (Phytophthora infestans) on tomato foliage

If you suspect your crop is affected by Phytophthora, contact your local extension agent, agronomist, or send samples directly to the NCSU Plant Disease and Insect Clinic to be sure you get a proper disease diagnosis.

For more information on managing Phytophthora diseases on vegetable crops, see:

Phytophthora Blight of Cucurbits
Phytophthora Blight of Peppers

For management on Phytophthora diseases on tomato, the same cultural practices apply as recommended for cucurbits and peppers, but see the disease factsheet on Late Blight on Tomato for products that will control Phytophthora as products that manage late blight will also manage other Phytophthora diseases on tomato, if the label allows. For example, Presidio, Orondis Ultra and Opti, and Zampro are labeled for PHytophthora blight (Phytophthora capsici)in addition to late blight (P. infestans).

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Photo of Inga Meadows, N.C. Cooperative ExtensionInga MeadowsExtension Associate, Vegetable and Herbaceous Ornamental Pathology (828) 456-3943 inga_meadows@ncsu.eduEntomology and Plant Pathology - NC State University
Updated on Jun 21, 2018
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