Fusarium Rot of Cucurbits

Pest Management Fact Sheet #5093

For information about UMaine Extension programs and resources, visit extension.umaine.edu.
Find more of our publications and books at extensionpubs.umext.maine.edu.

Introduction

Fusarium solani f.sp. cucurbitae causes foot, root, stem, and fruit rot of cucurbits. At least two races are known, one of which attacks only the fruit (Race 2) whereas Race 1 can attack the root, foot, stem, and fruit. This disease tends to be most serious on squash and pumpkin but other cucurbits are also susceptible. Although it is not a common disease, it has been found in Maine and it can cause significant crop loss.

Environmental Conditions

There is no clear indication of the environmental conditions which are necessary for this disease. The plant can be attacked at any time following seed germination. Conditions which discourage rapid germination and growth, such as cool wet soil, are likely to favor the disease. It is also suggested that Fusarium may follow other injuries such as fertilizer injury or drought.

Symptoms

Early symptoms may appear as a damping-off where young plants fall over and die. As the season progresses the disease may be expressed as stunting and sudden wilting may occur during hot dry weather because the rotting stem cannot transport sufficient water to the plant. The disease appears as a distinct brown decay at the base of the plant at the soil line. During wet weather the decay may turn soft and mushy and extend up the plant but dry weather may mask the infection as the decay remains below the soil. A white to pinkish growth may be evident when sufficient water is available.

Fruit may also be infected and the infection usually begins on the soil side. Fruit infections appear circular although multiple infections may merge and obscure concentric patterns. Fusarium fruit rot is usually firm and dry although secondary organisms may invade and cause a wet rot.

Survival and Dispersal

This fungus is soil-borne but it can also be carried by the seed. Seed transmission rates of 100% are possible. The fungus can survive up to three years in the soil or the seed. Spores of the fungus are produced on the infected plant material and can be transported by rain splash, running water, cultivation, and any other practice which transports soil around the field. The heaviest concentrations tend to be where infected plants were previously grown.

Control

Effective control of this disease relies on elimination of the fungus. This means using clean seed which is planted in uninfested soil. A three year rotation is probably sufficient to control the disease but a four year rotation may be advisable where problems have been severe. Hot water treatment of the seeds can help to clean them up (132°F for 15 min.) although reduced seed viability should be expected. In the greenhouse, sterile soil should be used. There are no resistant varieties available and there are no effective fungicides.


When Using Pesticides

ALWAYS FOLLOW LABEL DIRECTIONS!

Pest Management Unit
Cooperative Extension Diagnostic and Research Laboratory
17 Godfrey Drive, Orono, ME 04473-1295
1.800.287.0279 (in Maine)


Information in this publication is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.

© 2010

Call 800.287.0274 (in Maine), or 207.581.3188, for information on publications and program offerings from University of Maine Cooperative Extension, or visit extension.umaine.edu.

The University of Maine is an EEO/AA employer, and does not discriminate on the grounds of race, color, religion, sex, sexual orientation, transgender status, gender expression, national origin, citizenship status, age, disability, genetic information or veteran’s status in employment, education, and all other programs and activities. The following person has been designated to handle inquiries regarding non-discrimination policies: Sarah E. Harebo, Director of Equal Opportunity, 101 North Stevens Hall, University of Maine, Orono, ME 04469-5754, 207.581.1226, TTY 711 (Maine Relay System).