Effect of temperature on virulence of Rhizoctonia solani on soybean leaves and seedlings |
| |
| Authors: | C S KOUSIK† J P SNOW G T BERGGREN B G HARVILLE |
| |
| Institution: | Department of Plant Pathology and Crop Physiology, and, Louisiana Agricultural Experimental Station, Louisiana State University Agricultural Center, Baton Rouge, LA 70803;Department of Agronomy, Louisiana Agricultural Experimental Station, Louisiana State University Agricultural Center, Baton Rouge, LA 70803 |
| |
| Abstract: | Isolates representing 11 anastomosis groups (AGs) of Rhizoctonia solani from various geographic locations and host plants were tested for virulence on soybean leaves at 15, 20, 25, 30, and 35°C, and on soybean seedlings at 20, 25, and 30°C. Numbers of infection cushions formed on soybean leaves were determined using light microscopy. Isolates of AG-1 IA, AG-1 IB and AG-5 were more virulent on soybean leaves at 20, 25, and 30°C than isolates of AG-1 IC and AG-4. Maximum numbers of infection cushions were formed on soybean leaves by AG-1 (IA, IB, and IC), AG-4, and AG-5 at 25 and 30°C. The other AGs tested did not form infection cushions on soybean leaves although some caused minimal disease severity. Isolates of AG-1 IA formed significantly more infection cushions and caused greater disease severity than AG-1 IB and other isolates at 35°C. Maximum seedling infection, based on per cent area of hypocotyl region covered by lesions occurred at 25 C for AG-1 (IA, IB, and IC) and AG-4. Isolates of AG-5 caused greater seedling infection at 20°C than at 25 and 30°C. The other AGs tested caused only minimal damage to the seedlings. Isolates of AG-4 and AG-5 are not known to cause Rhizoctonia foliar blights of soybean in Louisiana, but their potential to be destructive foliar pathogens is confirmed. |
| |
| Keywords: | |
|
|
