Biological control of Fusarium head blight in wheat with Clonostachys rosea on maize residues – steps towards implementation into agricultural practice

Abstract: Fusarium graminearum (FG) is the main causal agent of the devastating cereal disease Fusarium head blight (FHB), leading not only to severe yield reductions but also to contamination of harvested cereal grains with health threatening mycotoxins. The currently available pre-harvest control measures are not always feasible or sufficient to control FHB. Hence, antagonistic fungi such as Clonostachys rosea as competitors on infected residues of the previous crop could be a valuable control measure. Following several encouraging results from in vitro experiments, we evaluated whether an application of FG-infected maize stalks with C. rosea could reduce FHB in subsequently grown wheat under field conditions. Hence, a system with high disease pressure, that is, a maize-wheat rotation under no-tillage, was simulated by preparing maize stalks inoculated with FG. The infected stalks were treated with C. rosea, placed between winter wheat rows and exposed to field conditions over winter and spring. The monitoring with spore traps and of FHB symptoms as well as the analyses of deoxynivalenol and zearalenone in harvested grains revealed reductions by C. rosea by up to 85, 91, 93 and 98 % compared with an inoculated but untreated positive control, respectively. To obtain practicable solutions to control FHB, C. rosea should be applied directly during maize harvest and the mulching of maize crop residues. In a recent study, alginate-based microcapsules containing C. rosea conidia were applied in autumn on naturally FG-infected maize residues under field conditions in a microplot experiment. Results on survival after winter are encouraging as growth and sporulation of C. rosea on maize residues were observed. The findings of this study support our hypothesis that an application of C. rosea against FG on maize residues has an excellent potential to sustainably control FHB.