Local Trichoderma strains as a control strategy of complex black root rot disease of strawberry in Egypt

Abstract

Background Economics and human safety to avoid health risks caused by fungicides are materializing new era of biological pest control. Trichoderma species ranked high among other agents to control complex black root rot disease of strawberry caused by Fusarium solani, Rhizoctonia solani, and Pythium sp. Our study aimed to document the efficacy of local strains representing T. harzianum, T. viride, T. virinis, and T. koningii against such a disease. Materials/methods These strains were cultured separately on potato dextrose broth medium to test their inhibitory effect against strawberry black root rot in vitro and in vivo. Strawberry growth and yield were also assessed relative to the untreated check and the fungicide Actamyl. Activity of peroxidase and chitinase were measured in plant leaves using spectrophotometer. Results Each of the antagonistic fungal strains significantly reduced growth area of all pathogenic fungi collectively causing the disease. Trichoderma harzianum, T. viride, and T. koningii reduced the growth area more than 90.6% for all tested pathogenic fungi. Each species significantly reduced disease incidence and severity under field conditions. The highest reduction in the disease incidence and severity, 83.3 and 88.5% respectively, was attained by mixture of the four species. This mixture increased the strawberry fresh and dry weight by 83.3 and 176.9%, respectively, and the yield by 117.1%. All Trichoderma species tested significantly increased the activity of two plant defense-related enzymes of strawberry plants against the pathogens. Their mixture attained the highest increase of peroxidase and chitinase activity by 150 and 160.9%, respectively. Conclusions While the fungal mixture could considerably increase the strawberry fresh and dry weight as well as the yield, it suppressed the incidence and severity of the disease. So, integrated pest management in ways that make these biocontrol agents complementary or superior to chemical fungicides should further be examined against this disease.

Influence of chitinase production on the antagonistic activity of Trichoderma against plant-pathogenic fungi

“…Partial degradation of host cell wall was observed at later stages of this process (Hassan, 2014). The effects of cell wall degrading enzymes on the host have been reported previously using different ultrastructural and/or histochemical approaches (Hassan, 2014;Abd-El-Kareem et al, 2019;Mazrou et al, 2020b).…”

“…Therefore, it can act against pathogenic fungi before interacting with the two mycelia, thus increasing the antagonistic capacity of Trichoderma (Fahmi et al, 2012;Filizola et al, 2019). Enzymes chitinase and glucanase are produced by Trichoderma species, but these enzymes are mainly expressed in the presence of their respective substrates (chitin and glucan) (Gajera and Vakharia 2012;Rana et al, 2012;Hassan 2014;Abd-El-Kareem et al, 2019).…”

“…The chitinases from Trichoderma species belong to glycosyl hydrolase family, and can be grouped into categories III and V. Various chitinase genes from Trichoderma spp. have been reported and characterized worldwide with emphasis on their roles in biological control strategies (Binod et al, 2007;Hassan et al, 2014;Abd-El-Kareem et al, 2019). Substrates like solid chitin, colloidal chitin, or red chitin can be used to evaluate chitinase activity.…”

Application of Bacillus pumilus isolates for management of black rot disease in strawberry

“…In Egypt, the most serious and damaging fungi on strawberry are Rhizoctonia solani and Fusarium solani together or in addition to Pythium sp. (Abdel-Sattar et al 2008;Abd-El-Kareem et al 2019). Many other pathogenic fungi were reported on strawberry in Egypt and worldwide.…”

“…Generally, growing dissatisfaction with the application of MB and other chemical pesticides has recently attracted much attention towards biocontrol of plant diseases as a safe and alternative strategy for the frequently risky chemical control (Noling 2016, Abd-Elgawad 2020. Hence, new safe and effective solutions to control black root rot of strawberry are desperately needed (Abd-El-Kareem et al 2019). Biocontrol agents included several Bacillus spp., which could not only suppress the causal pathogens but also increase the yields of the treated plant species.…”