Application of microorganisms, alone or in combination, to control postbloom fruit drop in citrus

Abstract

Isolates of Trichoderma spp. (ACB-14, ACB-33, ACB-37, and ACB-40) and Bacillus subtilis (ACB-66, ACB-69, ACB-77, and ACB-83) were tested separately or in mixtures for suppression of postbloom fruit drop in citrus, caused by Colletotrichum acutatum. This work aimed at: (i) determining the incubation time and temperature for production of cells of biocontrol agents; (ii) determining the effect of the isolates, separately or in mixture on the germination conidia of C. acutatum; (iii) evaluating the efficiency of antagonistic isolates on detached citrus flowers and under field conditions. The results of the interactions in vitro showed that there was little differentiation in cell production among the species, and the optimum temperature was 27°C. The best time for multiplication of bacterial cells was 36 hours, whereas for Trichoderma, the production of conidia continued to increase up to 120 hours of incubation. The mixtures of the ACB-77 plus ACB-66, ACB-33, or ACB-37 inhibited pathogen germination from 84% to 89%. Studies with detached citrus flowers showed that ACB-69 alone gave 99% control. The use of mixture ACB-69 plus ACB-37 proved to be viable in the control of disease under field conditions, but the efficiency of the control was lowest than the obtained by applications of ACB-69 alone.

Enhanced control of postharvest citrus fruit decay by means of the combined use of compatible biocontrol agents

“…The use of mixtures of complementary BCAs may present some advantages as a more wide target-pathogens range and a high effective disease control under different environmental conditions. However, the combined use of BCAs can sometimes produce a competition among them, reducing the efficacy of single compound and, thus of the corresponding mixture as recently reported by Klein et al (2013). In the present study, the efficacy of BCAs in mixture was evaluated on orange and lemon fruits.…”

Assessing Copper-Alternative Products for the Control of Pre- and Postharvest Citrus Anthracnose

“…in citrus fruits. Bacillus subtilis showed efficacy under field conditions in controlling postbloom fruit drop (PFD) caused by C. abscissum (previously reported as C. acutatum) or C. gloeosporioides [ 76 , 77 ] and S. cerevisiae isolates showed to be effective in controlling C. abscissum both preventively and curatively in preharvest experiments [ 78 ]. On the whole, biocontrol agents are rarely employed in open field, because they are often poorly resistant to environmental conditions encountered in the field, which negatively influence survival and antagonistic behavior.…”

Efficacy of five Trichoderma species against anthracnose in pecan through mycoparasitism and antibiosis

“…), in the control of C. musa (Oliveira et al 2016) and in Citrus spp., in the control of Colletotrichum spp. (Klein et al 2013). In this sense, Trichoderma spp.…”