Colonization of Clonostachys rosea on soybean root grown in media inoculated with Fusarium graminearum

Soybean root rot, caused by Fusarium graminearum, is an important disease in Canada. Clonostachys rosea has been reported to provide protection against plant pathogens in different crops. The objectives of this study were to determine if a strain of C. rosea, ACM 941, can colonize soybean root that were grown in media inoculated with F. graminearum, and to determine if the distribution of C. rosea was different at different root depths. There were three treatments in this study, which included a control (CK) using normal seed without any fungal treatments; seed inoculated with ACM 941 (ACM); and seed inoculated ACM 941 and growing media inoculated with F. graminearum (ACM +Fg). Results showed that the colony forming unit (CFU) of ACM 941 was lower on the tap roots and secondary roots growing 8-13 cm below ground level than sections of roots growing 0-3 cm or 3-8 cm below ground level. ACM 941 was found in roots at the third day after soybean seed was planted, and maintained high CFU most of the time during soybean growth. Inoculation with F. graminearum had no effect on CFU of ACM 941. The ACM 941 strain colonized soybean root rapidly and was not affected by the existence of F. graminearum, suggesting that ACM 941 can successfully compete with F. graminearum, may have potential as an effective biocontrol agent for protecting soybean from the Fusarium root rot.