Purdue University
Department of Botany and Plant Pathology Lilly Hall of Life Sciences
Plant Disease Control

BP-8-12
April 1974

Anthracnose of Melons and Its Control
Walter R. Stevenson, Donald H. Scott, Paul C. Pecknold, Extension Plant Pathologists

Anthracnose of melons is a widespread and destructive disease of vine crops caused by the fungus Colletrotrichum lagenarium.
This destructive to cantaloupe, cucumber, watermelon, most gourds, and many weeds in the cucurbit family. Pumpkin and squash are virtually immune.

How to Recognize Anthracnose

Anthracnose first appears as pale yellow, soaked spots on the older leaves near the crown. These spots soon enlarge and run together, turning tan to brown (most curcurbits) or black (watermelon). Affected areas may tear or drop out during strong winds and heavy rains, giving the leaves a tattered appearance. In dry weather, leaf infections spread slowly, but in rainy or camp weather they increase rapidly in size and number. Anthracnose spots may also appear on leaf petioles as elongated, sunken, dark colored areas. In wet weather, leaf infections may cause serious loss of foliage and will serve as a source of inoculum for infection later in the season. Defoliation and killing of infected vines are common. Young fruits infected with anthracnose frequently turn black, fail to develop,
shrivel and die. On older fruits, circular water-soaked lesions develop quite rapidly, particularly in periods of rainy or damp weather. Lesions become sunken and pink, but later turn dark green to black with flesh-colored, oozing centers. Anthracnose-infected melons and cucumbers are unattractive, bitter and unpalatable, usually decay rapidly, and are rejected at the market outlet.

The anthracnose fungus overwinters on crop refuse and may persist on infested seed or on weeds of the cucurbit family. It may survive in the soil for several years from where it can be spread from plant to plant by splashing rain and surface water. Most of the damage from anthracnose occurs late in the season when fruits are maturing.

How to Control Melon Anthracnose

There is no simple, one-shot method to prevent losses by anthracnose. Successful and economical prevention can be achieved only by the careful observance of the following suggestions:

1.	Plant melons in well-drained soil free from surface run off water and rotate with crops other than curcurbits in a 3-year
Cooperative Extension Work in Agriculture and Home Economics, State of Indiana, Purdue University and U. S. Department of Agriculture Cooperating. H. G. Diesslin, Director, West Lafayette, Ind. Issued in furtherance of the Acts of May 8 and June 30 1914. It is the policy of the Cooperative Extension Service of Purdue University that all persons shall have equal opportunity and access to its programs and facilities without regard to race, religion, color, sex or national origin.