![]() ![]() Rots appear on the melon rind which at first may go unnoticed. (See Photo of Downy Mildew)įusarium Rind Rot – (fungus – Fusarium roseum): Rind rot is mainly a cantaloupe disease. Preventative fungicide applications should begin at bloom and continue until the crop is harvested. Resistant varieties should be used when possible. Hot, dry weather may reduce or stop disease development. Cool temperatures along with free moisture are ideal for mildew infection and spread. Spores are easily carried by wind from diseased plants. This growth is more noticeable early in the morning when heavy dew is present. The underside of leaves, opposite the yellow spots, becomes covered with grayish growth which is the spore producing structures of the fungus. Greatest damage by this disease is caused during prolonged damp weather.ĭowny Mildew – (fungus – Pseudoperonospora cubensis): Angular yellow spots appear on the upper surface of the leaf during periods of high humidity. The fungus is usually confined to the end of the fruit, but if conditions favorable for disease development prevail, the entire fruit may decay. ![]() The blossom ends of fruit turn black, watersoaked, and covered by a fungal growth. Dry conditions are normally associated with charcoal rot.Ĭhoanephora Wet-Rot – (fungus – Choanephora cucurbitarum): This disease occurs almost exclusively on crenshaw, squash and pumpkins. Crop rotation may be of limited use since the fungus affects a large number of hosts, including corn and grain sorghum. Black, hard bodies produced by the fungus, known as sclerotia, are found on the surface of the cankers. Close observation of the crown will reveal brown cankers on the stems both below and above the soil line. As the disease progresses, entire runners wilt and die. First symptoms are dying of leaves close to the crown. Preventative fungicide applications will protect plants against infection.Ĭharcoal Rot – (fungus – Macrophomina phaseolina): Symptoms resemble those of gummy-stem blight and other vine diseases of melons. Preventative fungicide applications, as recommended for downy mildew control, should be made if weather conditions are favorable for disease development. Seed treatment, crop rotation and destruction of crop residues are important practices for the control of this disease. All above ground portions may be infected. Disease appearance in the field depends mainly on rainy, cool weather for a period of several days. Plants may be infected at any stage of growth. The fungus overwinters on old cucurbit vines and residues. When abundant moisture is present, the center of the spot is surrounded by a gelatinous pink mass. Symptoms on fruits consist of circular, black, sunken, cankers varying in size depending on the host plant. Diseased tissue dries and the center of the spots fall out, giving the leaf a “shot-hole” appearance. Spots enlarge and turn brown to black in color. See fungicide Īnthracnose – (fungus – Colletotrichum obiculare): First symptoms are spots on the foliage that begin as yellowish or watersoaked areas. Cucurbits, however, are sensitive to copper when young, and repeated applications of copper may cause yellowing of foliage around the edges of the leaves. Application of copper fungicide will assist in control. Crop rotation with non-cucurbit crops is helpful for control of angular leaf spot. The disease may reach epidemic proportions during periods of heavy rains, particularly if temperatures remain high. Hard rains splash the bacteria to stems and leaves. Bacteria overwinter in crop residue and on seed. Spots on fruit are usually smaller and circular in shape. Leaf spots often dry and fall out giving the leaf a “shot-hole” appearance, similar to those caused by anthracnose. Spots are small, angular, straw-colored and watersoaked. lacrymans): This disease appears on leaves, stems and fruit. (See Photo of Alternaria Leaf Spot)Īngular Leaf Spot – (bacterium – Pseudomonas syringae pv. A preventative fungicide program should be followed when the disease occurs consistently. Numerous air-borne spores are produced on diseased spots. The fungus overwinters in crop residue and on other cucurbit plants. Definite concentric rings and margins appear giving the diseased area a “bull’s eye” appearance. Alternaria Leaf Spot – (fungus – Alternaria cucumerina): Small, circular watersoaked spots first appear on the leaves, later enlarging to one and one-half inch or more in diameter. ![]()
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