High doses of fungicide on sugar beet seeds are less effective to Rhizoctonia solani at greenhouse condition.

Abstract

Rhizoctonia solani is a soil-borne plant pathogen, this necrotrophic fungus has been reported to cause damping-off, and crown and root rot in all sugar beet growing regions in the US. Therefore, we investigated the response of two cultivars against Rhizoctonia propagules, the seeds of two cultivars were pre-treated with different doses of Kabina and Systiva, and the seeds were sown under two different temperature regimes (65° F and 75° F). Our study demonstrated that moderate doses of Kabina (14 g) and Systiva (2.5 g) protected above 50% of the plants compared to untreated inoculated checks. But those rates did not show a significant increase in the number of stands than other lower doses of seed treatment. Our preliminary study further demonstrated that the high doses of both Kabina and Systiva failed to protect the plants against R. solani up to 20 weeks of post-inoculation. In summary, our data illustrated that high doses of fungicides are not always the best solution in protecting plants from Rhizoctonia solani rather increasing phytotoxicity to sugar beet seedlings.