Potential of Trichoderma piluliferum as a biocontrol agent of Colletotrichum musae in banana fruits

Microbial antagonists to biologically control postharvest decay and preserve fruit quality

Postharvest waste due to decay of fruits and vegetables negatively affects food security, while at the same time control of decay and therefore waste can be limited because of consumer concerns about use of synthetic chemicals. Use of antagonistic microorganisms is an eco-friendly technique that represents a promising alternative approach to the use of chemical methods. Understanding the interactions between antagonists and the fruit microbiome will enable the discovery of new methods to reduce postharvest waste. This article reviews different microbial agents, fungi, bacteria and yeasts that could control decay. Recent developments in the use of microorganisms for preserving postharvest fruit quality, formulation of effective antagonists, and the commercialization steps are also discussed. Antagonists control decay through either direct or indirect mechanisms while preserving the appearance, flavor, texture and nutritional value of horticultural products. Microorganisms do not fully control pathogens, and therefore they are usually used with other treatments or have their biocontrol ability modified through genetic manipulations. Despite of these limitations, commercialization of biocontrol products based on antagonists with required stability and biocontrol potential is occurring. Biocontrol of postharvest decay and waste agent is promising technology for fruit and vegetable industries. Further study is necessary to better understand mechanisms and increasing efficiency of this method.

Evaluation of Trichoderma atroviride and Trichoderma longibrachiatum as biocontrol agents in controlling red pepper anthracnose in Korea

Anthracnose disease is a serious threat to red pepper crops in Korea and many other countries, resulting in considerable yield losses. There are now no effective control techniques available except for fungicide sprays, which may directly impact consumers. This study aims to investigate the biological activity of Trichoderma isolates in controlling red pepper anthracnose caused by Colletotrichum acutatum in vitro and in the field. Out of 11 Trichoderma isolates screened for biocontrol agents against three fungal pathogens, including C. acutatum; two effective Trichoderma isolates, T. atroviride ATR697 (ATR697) and T. longibrachiatum LON701 (LON701) were selected for further investigation. Using the overlapping plates experiment, it was discovered that the volatile organic compounds (VOCs) produced by ATR697 strongly inhibited C. acutatum mycelial growth to a larger extent than the isolate LON701. A cellophane membrane experiment has shown that mycelial growth of C. acutatum was inhibited by 36% and 27% when treated with ATR697 and LON701, respectively. Culture filtrates (CFs) of two Trichoderma isolates inhibited the mycelial growth of C. acutatum in vitro. When red peppers were treated with spore suspensions of LON701 and ATR697, the disease severity (%) was 44.1% and 55.8%, respectively, in a curative method; while the disease severity (%) was 5% and 11.6%, in LON701- and ATR697-treated red peppers, respectively, in a preventive method. These results showed the suppression of disease severity (%) was relatively higher in the preventive method than in the curative method. Furthermore, Trichoderma isolates ATR697 and LON701 were resistant to commercial chemical fungicides in vitro, indicating these strains may also be used synergistically with a chemical fungicide (pyraclostrobin) against the growth of C. acutatum. There was no difference in the inhibition rate (%) of the pathogen between the treatment with LON701 alone and LON701+pyraclostrobin. Based on in vitro findings, ATR697 and LON701 played a role in effectively controlling red pepper anthracnose in field conditions, with LON701 treatment resulting in a disease rate of 14% when compared to ATR697, chemical, and non-treated controls. Overall, our study showed the ability of Trichoderma isolates to control red pepper anthracnose and their potential to develop as novel biocontrol agents to replace chemical fungicides for eco-friendly, sustainable agriculture.

Biocontrol potential of Trichoderma harzianum CGMCC20739 (Tha739) against postharvest bitter rot of apples

This study investigated the biocontrol ability of Trichoderma harzianum CGMCC20739 (Tha739) against apple bitter rot caused by Colletotrichum gloeosporioides. In vitro tests, Tha739 inhibited the mycelial growth of C. gloeosporioides. Microscopic observation showed that Tha739 grew in parallel with, coiled around, and deformed the hyphae of C. gloeosporioides. Tha739-derived metabolites decreased the conidia production of C. gloeosporioides. In vivo tests, the lesion diameters of wounded apples treated with Tha739 1 h before C. gloeosporioides were lower than those of wounded apples treated with Tha739 after pathogen inoculation. In addition, compared with the apples inoculated with C. gloeosporioides only, the disease index of unwounded apples inoculated with Tha739 and C. gloeosporioides decreased by 2.17-fold. Furthermore, compared with the control, the total soluble solid contents of apples treated with Tha739 were 9.02 % and 1.54 % higher at 1 and 3 d, respectively. The titratable acidity contents of apples treated with Tha739 were 10.02 % and 14.58 % higher than those in the control at 1 and 3 d after treatment, respectively. The soluble sugar content and weight loss in Tha739 treatment group and control were not significantly different. The results showed that Tha739 could control apple bitter rot and maintain the nutritional quality of the fruit. Thus, T. harzianum Tha739 is a potentially biocontrol agent for harvested apples.