Biocontrol capacity of wild and mutant Trichoderma harzianum (Rifai) strains on Rhizoctonia solani 618: effect of temperature and soil type during storage

Abstract

Wild (Th11, Th12 and Th650) and mutant (Th11A80.1, Th12A40.1, Th12C40.1 and Th650-NG7) Trichoderma harzianum strains were stored for 180 days at 5ºC or at 22ºC, in two types of soils. Strains recovered at 90, 120 and 180 days from the two types of soils, retained their full capacity to biocontrol Rhizoctonia solani 618, that produces crown and root rot of tomatoes. Recovery, estimated as colony forming units (cfu) of the wild and mutant strains, showed that all increased their cfu after storage independently of the type of soil and temperature, although kinetic behavior differed among strains. Ratios of recovery after storage in type B soil/ type A soil or at 22ºC/5ºC, higher or lower than one respectively, allowed to establish that Th11 and Th12 were the most appropriate strains for the biocontrol of R. solani in conditions where growth of the phytopathogen is optimal.

Sensitivity of wild-type and mutant Trichoderma harzianum strains tofungicides

“…This strategy, in addition to the persistence of these BCAs in the soil (Montealegre et al, 2009), should have a significant and positive impact on the environment.…”

“…Previous experiments have shown that certain wild-type and mutant Trichoderma strains can control some of these pathogens in vitro and in greenhouse conditions (Pérez et al, 2002;Arias et al, 2006;. Formulations containing these strains are stable; i.e., they retain full R. solani biocontrol activity after six months without reductions in the CFU count of the formulation (Montealegre et al, 2009). It is not known whether these Trichoderma strains are sensitive to the fungicides used to control those plant pathogens.…”

<i>Trichoderma harzianum</i> como herramienta en el manejo integrado de enfermedades de tomate

“…harzianum como antagonista de patógenos de plantas se encontraría estrechamente relacionada con su formulación, ya que tiene influencia directa en su supervivencia en el suelo. Entre los principales factores que influyen en su éxito, se hallarían la temperatura y tipo de suelo (Montealegre et al 2009;Stocco et al 2019) El trabajo de Mónaco et al (2006) donde se caracterizaron molecularmente cepas de Trichoderma, y se evaluaron su crecimiento in vitro junto con los patógenos Pythium sp. y Rhizoctonia sp., demostró el crecimiento de Trichoderma virens alrededor de las hifas de los patógenos, efecto que se corroboró en ensayos con semillas de albahaca y tomate.…”