RECOVERY OF COCHLIOBOLUS-SATIVUS AND FUSARIUM-GRAMINEARUM FROM LIVING AND DEAD WHEAT AND NONGRAMINEOUS WINTER CROPS IN SOUTHERN BRAZIL

Wheat and several nongramineous plant species, commonly used in rotation with wheat in southern and central Brazil, were examined for the presence of the wheat pathogens Cochliobolus sativus and Fusarium graminearum. Both fungi were isolated from residues of all the plant species, artificially inoculated and grown in a growth chamber, or grown outdoors exposed to inoculum in the form of infested sorghum grains. After harvest of outdoor plants, recovery was lower in 4-month-old residues than in 5-week-old residues. These fungi were also recovered from healthy and lesioned parts of many of these plant species collected in the field. Artificially inoculated nongramineous plants did not show any symptoms of infection and microscopic examination of inoculated leaves showed a resistant reaction to C. sativus.