Fusarium Rot of Cucurbits

Pest Management Fact Sheet #5093

Authors: Dr. Alicyn Smart, Dr. Bruce Watt, Abigayl Novak, and Nathan Andrews

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Other Name: Fusarium Wilt of Cucurbits, Fusarium Fruit Rot
Pathogen: Fusarium solani f.sp. cucurbitae

Introduction

Figure 1. Progressed fruit rot on a cantaloupe. Photo by Dr. Bruce Watt.

Fusarium Rot of Cucurbits is a fungal disease that can affect the roots, stem, and fruit, particularly pumpkins and squash. The disease consists of two different races (pathovars) — race 1 targets the stems, roots, and fruit of the plant while race 2 only targets the fruit. Cool, wet conditions tend to be the most favorable for this pathogen to grow. Infection of fruit is greatest in fruit that is in direct contact with soil. Fusarium rot can also be an opportunistic disease, infecting hosts after winter damage, fertilizer injury or a primary pathogen has weakened the plant, making it more susceptible to other pathogens.

Host Plants

Cucurbits (family Cucurbitaceae)

Management

Remove all infected plants
Use clean seed during planting
Rotate cucurbit crops out every 3-4 years
Space out plants out while planting to increase airflow.
There are no resistant varieties or effective fungicides for this disease

You should check your local town ordinance for any pesticide restrictions before application

Symptoms and Signs

Initial infection of the whole plant may appear as damping off during the seedling stage. Wilting may be seen during the warmest part of the day and then in the evening the plant recovers. This is because the fungi inhabit the space where water is transported, and the plant is then unable to transport sufficient amounts of water to the leaves. During the cooler temperatures of the evening, the plant can regain the turgor pressure of the leaves. Browning of the main stem at the soil line is also commonly seen and possibly a rot if found in wet conditions or a scar in dry conditions.

Initial infection of fruit will begin where the fruit touches the soil. Infected fruit will develop lesions that are usually circular and can vary in size. The tissue beneath can be discolored and have a corky texture. As lesions develop, the coloration will progress to a whitish pink, and rot will form. Fusarium rot is initially dry and firm, but secondary organisms may cause a wet rot to form.

References

Seebold, Kenny (2010, November). Fruit Rot of Cucurbits. Retrieved from University of Kentucky – Plant Pathology Extension: https://plantpathology.ca.uky.edu/files/ppfs-vg-07.pdf

Fusarium Fruit Rot. 2013. Retrieved from University of Massachusetts Amherst Extension: https://ag.umass.edu/vegetable/fact-sheets/cucurbits-fusarium-fruit-rot

WHEN USING PESTICIDES, ALWAYS FOLLOW LABEL DIRECTIONS!

Alicyn Smart, DPM
Plant Pathologist and Director of the Plant Disease Diagnostic Laboratory
University of Maine Cooperative Extension

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Cooperative Extension: Insect Pests, Ticks and Plant Diseases