Evaluation of Trichoderma spp. on Fusarium oxysporum f. sp. asparagi and Fusarium wilt Control in Asparagus Crop

Abstract

Among the key diseases affecting the asparagus crop (Asparagus officinalis L.), vascular wilting of asparagus caused by Fusarium oxysporum f. sp. asparagi stands out worldwide. This disease significantly shortens the longevity of the crop and limits economic production. Traditional control measures have been largely ineffective, and chemical control methods are difficult to apply, making biological control approaches, specifically the use of Trichoderma, an economical, effective, and risk-free alternative. This study aimed to identify the main factors that affect the efficacy of biopesticides studied as Biological Control Agents (BCAs) against Fusarium wilt in asparagus and to assess the efficacy of Trichoderma-based biopesticides under greenhouse and semi-field conditions. We evaluated the response of three Trichoderma spp. (T. atroviride, T. asperellum, and T. saturnisporum) to environmental variables, such as temperature and water activity, and their antagonistic capacity against Fusarium oxysporum f. sp. asparagi. All three Trichoderma species inhibited the growth of the pathogen in vitro. A decrease in water activity led to a greater reduction in the growth rate. The efficacy of the three biological control agents decreased with higher temperatures, resulting in minimal inhibition, particularly under conditions of restricted available water in the environment. The effect of the fungal inoculum density was also analyzed at two different temperatures. A direct correlation between the amount of inoculum and the score on the Disease Severity Index (DSI) was observed. A notable reduction in DSI was evident in treatments with high inoculum density (106 conidium/mL) for all three species of Trichoderma tested at both temperatures. In greenhouse and semi-field tests, we observed less disease control than expected, although T. asperellum and T. atroviride showed lower disease severity indices and increased the dry weight of seedlings and crowns, whereas T. saturnisporum resulted in the highest disease rate and lowest dry weight. This work highlights that the efficacy of Trichoderma as BCAs is influenced by various factors, including the quantity of soil inocula, and environmental conditions. The study findings have strong implications for selecting appropriate Trichoderma species for controlling specific pathogens under specific environmental conditions.

Antifungal Potential of Bacillus subtilis subsp. inaquosorum RLS76 for Management of Fusarium Wilt Disease of Bt- Cotton

“…Some rhizobacteria exhibit plant growth-promoting (PGPR) and biocontrol properties, making them promising candidates for managing plant diseases. Researchers identified different microorganisms such as Bacillus sp., 6,7 Pseudomonas sp., [8][9][10] Serratia sp., 8,11 and Trichoderma sp., [12][13][14][15] which would be potential candidates for management of plant diseases instead of chemical fungicides.…”

Isolation and Identification of Bacillus subtilis LY-1 and Its Antifungal and Growth-Promoting Effects

“…It has been reported that the biocontrol bacteria and fungi that have been shown to control plant root rot caused by Fusarium mainly include species of Bacillus [ 9 ], Penicillium [ 10 ], Pseudomonas [ 11 ], Streptomyces [ 12 ], and Trichoderma [ 13 ]. Among these, Bacillus has several beneficial characteristics, such as UV resistance, salt tolerance, and heat tolerance [ 14 , 15 , 16 ].…”