MANAGEMENT OF WHEAT AND BARLEY ROOT ROT THROUGH SEED TREATMENT WITH BIOPESTCIDES AND FUNGICIDES

Biological and chemical treatments of seeds with a Trichoderma suspension or solutions of Thirame with 10% gelatin, 4% superphosphate, and 0.1% sucrose were able to reduce the severity, incidence and index of root rot in wheat and barley plants growing on a substrate inoculated with three pathogens responsible for root rot, Curvularia spicifera, Bipolaris sorokiniana, and Fusarium roseum. In general, the S4 severity class was not observed in wheat plants from Trichoderma treated seeds or the fungicide. Sometimes even S3 and S2 classes were not found, in the case of durum wheat plants from treated seeds with Trichoderma growing on a substrate inoculated with B. sorokiniana. Barley plants from treated grain are much more protected than wheat plants, Classes S3 and S4 have not been observed and sometimes protection against B. sorokiniana is total in the case of plants from seeds treated with Trichoderma. In soft and hard wheat plants from Trichoderma or Thiram treatment, incidences and indices of root rot ranged respectively from 58.3% to 25%, compared to 100% and 83%, and between 51.6% and 23.3%, compared with 78.3% and 50%. In barley plants, incidences and indices of root rot ranged respectively from 50 to 16.7%, compared with 83.3 and 75% for controls and 30 to 18.3 and 51.6 to 27.7 for controls. Similarly, the development of C. spicifera and B. sorokiniana in the upper levels of wheat and barley plants decreased and leaf area indices were very low in plants from Trichoderma-treated seedlings. Treatment with this biocontrol agent has sometimes prevented wheat and barley from being infected by the tested pathogens, re-isolation from roots and foliar lesions was negative, and some symptoms developed in response to the age of seedlings do not harbor pathogens. The re isolation of Trichoderma was also positive from the roots of all the plants derived from the grains treated with this fungus.