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Publication #PDMG-V3-54

2009 Florida Plant Disease Management Guide: Watercress1

Pam Roberts2

Specific Common Diseases

Cercospora Leaf Spot (Cercospora nasturtii)

Symptoms: Round to oval lesions develop on leaves. Leaf spots are light-colored and may coalesce to cover large areas of tissue. The pathogen produces abundant spores that are easily water-splashed or airborne.

Cultural Control: Insure that previous watercress debris is well decomposed before replanting of land. Eradicate volunteer plants and weed relatives in the Nasturtium genus to prevent carry over of this fungus from the field perimeter.

Chemical Control: See PPP-6.

Damping-Off (Rhizoctonia, Pythium, Fusarium, and Sclerotinia spp.)

Symptoms: The distribution of seedlings that damp-off may be at random or in rapidly enlarging circular areas in the seedbeds. In the latter case, lesions may be observed well up on the petioles as well as the soil line. Entire plantings may be lost unless adequate control measures are practiced. Do not transplant disease plants.

Chemical Control: See PPP-6.

Rhizoctonia Rot (Rhizoctonia solani)

Symptoms: Rhizoctonia is a soilborne fungus that can cause a damping-off of seedlings or seeds, as well as a mature plant decline from rot and stem decay. The fungus often invades at soil line producing a light-to-reddish-brown canker on the lower stem. Lower leaves exhibit yellowing, followed by necrosis and progressive plant wilt to death.

Cultural Control: Insure summer vegetation or previous crop debris is well decomposed prior to planting.

Chemical Control: See PPP-6.

Viral Diseases (Cucumber mosaic, Cabbage Leaf Curl)

Symptoms: A single virus or multiple infection of several viruses can produce a variety of plant symptoms that include mosaic leaf distortion, ring spotting and stunting. Cucumber mosaic virus is vectored be aphids in a semi-persistent manner. Cabbage leaf curl virus is vectored by white flies.

Cultural Control: Clean field and field borders of volunteer crops and weeds to minimize reservoirs for both vector insects and viruses.

Footnotes

1.

This document is PDMG-V3-54, one of a series of the Department of Plant Pathology, 2009 Florida Plant Disease Management Guide, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Revised December 2005. Reviewed June 2009. Please visit the EDIS Web site at http://edis.ifas.ufl.edu.

2.

P.D. Roberts, associate professor, Southwest Florida Research and Education Center, Immokalee, FL; Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean.