Biocontrol Effects of Paecilomyces variotii against Fungal Plant Diseases

Abstract

The genus Paecilomyces is known for its potential application in the control of pests and diseases; however, its use in agriculture is limited to few species. Research interest in new formulations based on microorganisms for the control of pathogens is growing exponentially; therefore, it is necessary to study new isolates, which may help control diseases effectively, and to examine their compatibility with established agricultural control methods. We analysed in vitro and in vivo the antagonistic capacity of Paecilomyces variotii against seven phytopathogens with a high incidence in different crops, and we examined its compatibility with 24 commercial fungicides. P. variotii was applied in the following pathosystems: B. cinereal—melon, Sclerotinia sclerotiorum—pepper, R. solani—tomato, F. solani—zucchini, P. aphanidermatum—melon, M. melonis—melon, and P. xanthii—zucchini. The results showed strong control effects on M. melonis and P. xanthii, reducing the disease severity index by 78% and 76%, respectively. The reduction in disease severity in the other pathosystems ranged from 29% to 44%. However, application of metabolites alone did not cause any significant effect on mycelial growth of phytopathogens, apart from F. solani, in which up to 12% inhibition was observed in vitro when the extract was applied at a concentration of 15% in the medium. P. variotii was compatible with most of the tested fungicides, and of the 24 fungicides tested at the maximum authorised dose, 6 acted as fungicides, 4 as fungistatics, and the remaining showed inhibition rates ranging from 18.2% to 95.8%. These results indicate that P. variotii is a potential biological control agent to be used against several aerial and soil diseases, thus it should be integrated into modern pest management strategies.

Effect of Natural Polysaccharide Matrix-Based Selenium Nanocomposites on Phytophthora cactorum and Rhizospheric Microorganisms

“…The observation period ended when the control Petri dish was filled with mycelium (usually after 12 days). The inhibition (I) of the radial growth (R) of the phytopathogen by Se NCs or fludioxonil was calculated according to [ 41 , 42 ] as a percentage by which the normal radial growth was decreased compared to the control: I (%) = 100 × (R control − R treatment )/R control . The effective concentration causing 50% of growth inhibition (EC 50 ) was determined from dose-relative inhibition curves.…”

Biocontrol of Diseases Caused by Phytophthora capsici and P. parasitica in Pepper Plants

“…Among them, only the compound farinomalein, isolated from P. farinosus , was a potent inhibitor of the plant pathogen Phytophthora sojae . Moreno et al [ 152 ] did not assess high growth inhibition values of plant pathogens such as F. solani and M. melonis induced by N-VOCs and VOCs of P. variotii .…”

Synthesis and diverse biological activity profile of triethylammonium isatin-3-hydrazones

“…The inhibition of the phytopathogen colony growth by the compounds 3a,c-g or fludioxonil solutions was calculated as a percentage by which the mycelium radial propagation was decreased compared to the unaffected control, the latter was taken as 100 % of growth (or zero percent of inhibition). The EC 50 value was calculated as the compound concentration at which the radial growth of the fungus colony was decreased by 50 % relative to the non-fungicidal control, according to the formula EC 50 = 50C/I based on the approach developed e.g., in [ 34 , 35 ].…”