Evaluation of Trichoderma spp. and Clonostachys spp. Strains to Control Fusarium circinatum in Pinus radiata Seedlings

Abstract

The fungus Fusarium circinatum Nirenberg & O'Donnell causes pine pitch canker, an important disease for conifers worldwide. F. circinatum was first detected in Chile in 2001 and to date is present in nurseries and clonal hedges from Libertador General Bernardo O'Higgins Region to Los Ríos Region. The purpose of this study was to evaluate the potential of Trichoderma spp. and Clonostachys spp. strains to control F. circinatum in Pinus radiata D. Don seedlings in the absence of other effective control methods. Eighty-one Trichoderma spp. and Clonostachys spp. strains were evaluated through in vitro assays to determine their ability to act as antagonists of F. circinatum and 21 strains were tested for their ability to reduce post-emergence mortality and increase P. radiata survival under greenhouse conditions. During in vitro experiments, 15 strains of Trichoderma inhibited mycelial growth of the pathogen by more than 60% and one strain of Clonostachys showed parasitism of F. circinatum hyphae. Greenhouse experiments showed no control of the disease when the antagonists were added to substrate after the pathogen. However, when the antagonists were added before the pathogen, four strains (Clonostachys UDC-32 and UDC-222 and Trichoderma UDC-23 and UDC-408) reduced post-emergence mortality between 80 and 100%. Among these strains, only Clonostachys UDC-222 significantly increased the survival of P. radiata seedlings. These results showed that Clonostachys UDC-222 has the potential to be used as a biocontrol agent against F. circinatum in the production of P. radiata plants.

Susceptibility of Several Northeastern Conifers to Fusarium circinatum and Strategies for Biocontrol

“…Taking into account that in both studies the same F. circinatum isolate was used, this was probably due to the fact that they inoculated simultaneously the pathogen and T. viride. The importance of timing in the application of the BCA was already reported by Moraga-Suazo et al [40]. While Trichoderma strains exerted a reduction of the post-emergence mortality when they were added to substrate 7 days before adding the pathogen, no significant effect was found when they were added 48 h after the pathogen.…”

“…Several Trichoderma species, including T. atroviride and T. viride, have been already tested as BCAs against F. circinatum in P. radiata [39][40][41][42]64]. However, to our knowledge this is the first study that performs and demonstrates the antagonistic effect of Trichoderma species on F. circinatum in other hosts.…”

The frequency of modification of Dothistroma pine needle blight severity by fungi within the native range

“…glauca (Table 1) were selected and employed as putative disease modifiers. B. ochroleuca is a known parasite and antagonist of other fungi (Moraga-Suazo et al, 2011) and is found in understory litter of P. ponderosa (Ridout and Newcombe, unpublished).…”

Development of a genetic linkage map for Pinus radiata and detection of pitch canker disease resistance associated QTLs

“…Currently, there are some control measures that are being applied in nurseries, such as cultural control (Rotella 2005), chemical control (Gonzalez 2005;Mitchell et al 2005), and biological control (Moraga-Suazo et al 2011). Although these measures may control the disease in nurseries, they are not feasible for disease control on forest plantations.…”