四川省西北部稻区水稻纹枯病菌系研究

STUDIES ON THE STRAINS OF PATHOGENS OF SHEATH BLICHT OF RICE IN NORTHWEST SICHUAN PROVINCE

Threc hundred and forty-ninc samples of rice showing symptoms of sheat blight werecollected from ficlds in areas with different topography and clevation,with varying soilproperties and pre-cropped cultivars,and in different crop growth stages in 40 counties ofnorthwest Sichuan.Based on the symptoms,166 samples were identified as Rhizotoniawhen the isolates were tested with Gicsma dyeing method according to morphological andbiological characters.Two isolates were recognized as binuclcate Rhizoctonia and the other164 isolates as multinuclcate R.solani.This result is in agreement with the classification bythe international standard hyphal fusion method(ISHF).Of the 164 multinucleates,162were grouped into AG-1(anostomosis group 1)and 2 into AG-4;and of the 2 binucleates,one was grouped into AG-Bb and the other into AG-D.Pathogenicitical test showed thatall the isolates infected rice.Differences in pathogenicity existed,however,among the iso-lates,with AG-1 being the most infections,followed by AG-4,AG-Bb and AG-D.