Seed treatment containing Bacillus subtilis BY-2 in combination with other Bacillus isolates for control of Sclerotinia sclerotiorum on oilseed rape

Authors: HU, XIAOJIA - Chinese Academy Of Agricultural Sciences; Roberts, Daniel; XIE, LIHUA - Chinese Academy Of Agricultural Sciences; QIN, LU - Chinese Academy Of Agricultural Sciences; LI, YINSHUI - Chinese Academy Of Agricultural Sciences; LIAO, XIANGSHENG - Chinese Academy Of Agricultural Sciences; HAN, PEIPEI - Chinese Academy Of Agricultural Sciences; YU, CHANGBING - Chinese Academy Of Agricultural Sciences; LIAO, XING - Chinese Academy Of Agricultural Sciences

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2019
Publication Date: 3/19/2019
Citation: Hu, X., Roberts, D.P., Xie, L., Qin, L., Li, Y., Liao, X., Han, P., Yu, C., Liao, X. 2019. Seed treatment containing Bacillus subtilis BY-2 in combination with other Bacillus isolates for control of Sclerotinia sclerotiorum on oilseed rape. Biological Control. 133:50-57.

Interpretive Summary: The soilborne plant pathogen, Sclerotinia sclerotiorum, causes disease on a number of important crops that result in major economic losses to farmers in the United States. These diseases are controlled primarily through the use of chemical pesticides. Biological control measures need to be developed for this pathogen due to the loss of efficacy of existing chemical control measures and to the environmental problems associated with these chemicals. However, biological control agents must have enhanced levels of disease suppression and consistency of control before they enjoy wide-spread use in production agriculture. We tested Bacillus megaterium A6 and two B. subtilis isolates, BY-2 and Tu-100, individually and in combinations in field trials conducted in four locations with different soils for control of Sclerotinia sclerotiorum on oilseed rape. We found that seed treatments containing combinations of these biological control agents provided more consistent and higher levels of control of S. sclerotiorum over multiple soil types than treatments containing individual biological control agents. The information in this manuscript will be useful to scientists devising strategies for the control of soilborne plant pathogens.

Technical Abstract: Biological control agents must have enhanced levels of disease suppression and consistency of control before they enjoy wide-spread use in production agriculture. Treatments containing Bacillus megaterium A6 and two genetically distinct B. subtilis isolates, BY-2 and Tu-100, were applied individually and in combinations as seed treatments, and tested in field trials conducted in four locations with different soils for control of Sclerotinia sclerotiorum on oilseed rape. All bacterial treatments resulted in a significant decrease in disease incidence relative to the non-treated and formulation-only controls in at least two of the locations. There was also a general, incremental reduction in disease incidence with increasing number of isolates in the treatments at all four locations. Additionally, the treatment containing all three isolates resulted in an incidence of disease that was significantly lower than that associated with treatments containing individual isolates 75% of the time. Seed treatment containing these three isolates resulted in a significant increase in yield relative to the non-treated and formulation-only controls in two of the four field locations. The only other treatment to significantly increase yield relative to these controls contained two isolates and this was only at one field location. In plant growth promotion studies conducted in the greenhouse, the treatment containing all three isolates was the only treatment resulting in seed yield greater than the two controls in five different soils. The three combination treatments containing two isolates significantly increased yield in four, three, and two of the soils, respectively, in these greenhouse experiments. Only one treatment containing a single isolate, A6, significantly increased yield and this was only in one soil. Experiments reported here support the concept that treatments containing combinations of microbial biological control agents provide more consistent and higher levels of plant-beneficial activities over multiple soil types than treatments containing individual biological control agents.