Diseases of sweet sorghum and their control
1985
Vichai Korpraditskul | Kobkul Wipawasu | Nuan-anong Kitchamroen (Kasetsart Univ., Bangkok (Thailand). Faculty of Agriculture. Dept. of Plant Pathology)
Fusarium moniliforme, the causal organism of sweet sorghum disease, infected as well as expressed by 2 different symptoms is Fusarium root rot (stalk rot) and leaf sheath rot. Fusarium stalk rot is one of the most important diseases of sweet sorghum. The symptom can be easily recognized by the red scar long the outmost with the red rotten tissue inside. The severely infected plant produced less juice with low sugar content and the pith became dry. This pathogen produced septate mycelium with two types of spore, ie. microspore and macrospore. The optimum temperature for growth is 25-30 deg.celsius. Five fungicides, namely Captan, Dithane M-45, Difolatan, Vitavax and Zineb were tested to inhibit growth. Difolatan and Captan showed the best inhibitory effect. Leaf sheath rot occurred on leaf sheath and seedling, At first, the symptom expressed small red lesion on the leaf sheath. Two to three weeks later, the lesion became larger with irregular shape. Severely infected leaf sheath became necrosis and dead. Scaning electron microscopic study revealed that the numerous appressoria were formed at the apex of mycelium. This fungus directly penetrated into the seedling tissue and developed both intercellular and intracellular mycelia. The efficacy of 5 fungicides, namely Benlate, Captan, Difolatan, Dithane M-45 and Zineb was evaluated. Benlate showed best inhibitory effect followed by Difolatan and Captan, respectively.
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