In Vitro Sensitivity Test of Fusarium Species from Weeds and Non-Gramineous Plants to Triazole Fungicides

Abstract

Fusarium species are common plant pathogens that cause serious crop losses worldwide. Fusarium spp. colonize not only the main host plants, crops, but also alternative hosts. The effectiveness of fungicide use in disease management ranges from very successful to possibly promoting the growth of the pathogen. Triazole fungicides are widely used to control these pathogens due to their broad-spectrum activity and systemic nature. This paper reviews the sensitivity of 40 Fusarium strains isolated from weeds, non-gramineous plants, and spring wheat to metconazole, prothioconazole, and tebuconazole. The effect of fungicides was determined by the percentage inhibition of F. graminearum, F. culmorum, F. sporotrichioides, and F. avenaceum fungal mycelial growth. The 50% effective concentration (EC50) values of all isolates on metconazole were lower than 2.9 mg L^-1, prothioconazole EC50 ranged from 0.12 to 23.6 mg L^-1, and tebuconazole ranged from 0.09 to 15.6 mg L^-1. At 0.00025-0.025 mg L^-1, the fungicides were ineffective, except for the growth of the F. avenaceum species. It was observed that isolates from weeds were more sensitive to low concentrations of fungicide than isolates from crop plants. In general, information is scarce regarding the comparison of fungicide resistance in Fusarium isolates from weed and crop plants, making this study an additional contribution to the existing knowledge base.

Keywords: EC50; Fusarium; chemical control; fungicides; mycelium growth inhibition; non-gramineous plants; weed.

Figure 1

Mycelial growth inhibition (%) of four Fusarium species isolated from various plants at different concentrations of metconazole, prothioconazole, and tebuconazole. Fs—F. sporotrichioides, Fg—F. graminearum, Fc—F. culmorum, Fa—F. avenaceum. Concentrations: 1—0.00025, 2—0.0025, 3—0.025, 4—0.25, 5—2.5, 6—25 mg L⁻¹. The black circle indicates the median inhibition values of all Fusarium isolates from the indicated host plant. The blue bar shows a range from the minimum to maximum values. Error bars indicate ± SE.

Figure 2

Mycelial growth inhibition (%) of all Fusarium isolates under the influence of different fungicides and their concentrations. The concentrations of fungicides indicated on the Y-axis are 1—0.00025, 2—0.0025, 3—0.025, 4—0.25, 5—2.5, 6—25 mg L⁻¹. The black circle indicates the median inhibition values of all Fusarium isolates from the indicated host plant. The blue bar shows a range from the minimum to maximum values. Error bars indicate ±SE.

Figure 3

Mycelial growth inhibition of Fusarium sporotrichioides strain (45P) from wheat by different concentrations of metconazole (MET), prothioconazole (PRO), and tebuconazole (TEB). C—control plate without fungicides.