Field testing of honeybee‐dispersed Trichoderma spp. to manage sunflower head rot ( Sclerotinia sclerotiorum )

Efficacy of Trichoderma spp. to reduce sunflower head rot caused by Sclerotinia sclerotiorum was evaluated in the field. A mixture of six isolates, including Trichoderma koningii , T. aureoviride and T. longibrachiatum , was tested in five field trials at Balcarce, Argentina. Trichoderma formulation (TF) included Trichoderma conidia and viable hyphal fragments, industrial talc and milled corn kernels. Honeybees ( Apis mellifera ) were used to disperse TF for six weeks from the onset of flowering. Two days after the first TF delivery, sunflower heads were inoculated with S. sclerotiorum ascospores. When 100 g TF was taken by honeybees in a 10‐h per day period, head rot incidence was significantly reduced. This approach was successful in reducing disease incidence until physiological maturity of the crop, in environments highly conducive to head‐rot development.