Infection with basidiospores of Thanatephorus cucumeris (AG-2-3 of Rhizoctonia solani) and development of soybean [Glycine max] foliar blight lesions
1995
Naito, S. (Tohoku National Agricultural Experiment Station, Morioka (Japan)) | Mochida, H. | Nakajima, T. | Ohto, Y.
Soybean leaves artificially inoculated with basidiospores of Thanatephorus cucumeris (AG-2-3 of Rhizoctonia solani) developed at first, primary lesions, then, secondary lesions and eventually, irregular large-sized lesions. The germ tubes of the germinating basidiospores formed appressoria and their infection pegs penetrated into the epidermal cells. A stroma-like structure was produced within the invaded tissues. Hyphae growing readily from this structure formed circular necrotic spots which corresponded to the primary lesions. After further incubation in a moist chamber, hyphae from the primary lesions continued to grow on the leaf surface and hyphae tips re-entered the leaves through the stomata, causing secondary lesions with circular to irregularly shaped areas of necrosis around the primary lesions. The large-sized irregular lesions developed from additional hyphae infection through stomata. Many fruiting hymenia of the pathogen were detected on the stems of winter wheat or soybean, especially in fields where soybean was intercropped with winter wheat. The severity of the soybean foliar blight lesions caused by basidiospores increased with the delay in wheat harvest or with the increase of the soybean planting density
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