Effects of Herbicides on Root Rot and Damping-off Caused by Rhizoctonia solani in Glyphosate-Tolerant Soybean

Abstract

Diseases caused by Rhizoctonia solani are one of many production constraints in soybean-growing regions. Little information is available about the diseases in soybeans tolerant to different herbicides. In 1998 and 1999, studies were conducted to evaluate the plausible interaction between glyphosate-tolerant soybean and herbicides (glyphosate, imazethapyr, lactofen, and pendimethalin) on damping-off and root rot caused by R. solani under greenhouse and field conditions. The herbicides were applied at the product recommended field rate on glyphosate-tolerant (Pioneer 93B01 and Pioneer 9344) and glyphosate-sensitive (BSR 101) soybean grown in soils infested with R. solani (isolate AG-4). Root rot and plant stand was significantly affected by soybean cultivars and herbicide treatments in the greenhouse study. A significant cultivar-treatment interaction was detected in the greenhouse study. The interaction implies that the cultivars responded differently to the various herbicides and especially to the herbicide pendimethalin. Plant stands of both cultivars were reduced by R. solani alone or in combination with different herbicides compared with the noninoculated control, and this was presumed to be due to damping-off. In a 2-year field study, cultivar and treatment main effects differed with respect to plant stand between years. In 1998, analysis of variance revealed a significant treatment effect on root rot severity but not plant stand. In 1999, analysis of variance revealed a significant effect of treatment on root rot severity and plant stand whereas cultivar showed a significant effect on plant stand only. In 1999, plant stands of both cultivars were similarly affected by most treatments. However, in BSR 101, the R. solani + pendimethalin + imazethapyr treatment significantly reduced plant stand compared with the R. solani + pendimethalin treatment. Root rot severity was generally low in both years of the field study. Some differential disease responses were detected between glyphosate-tolerant and glyphosate-sensitive cultivars following the application of certain herbicides in greenhouse and field studies. However, glyphosate-tolerant and glyphosate-sensitive cultivars reacted similarly to most herbicide treatments with respect to root rot and damping off.

Microbial Degradation of Fluometuron Is Influenced by Roundup WeatherMAX

“…This is supportive of other research, which indicates that glyphosate application does not increase the occurrence of soybean diseases caused by R. solani (31). However, increased growth of other pathogens in response to glyphosate has been reported (9,32).…”

Ecological risk of long-term chlorimuron-ethyl application to soil microbial community: an in situ investigation in a continuously cropped soybean field in Northeast China

“…In fungal community structure, F. oxysporum, R. solani, and P. sojae are the pathogens of soybean root rot (Carson et al 1991;Ehteshamul-haque and Ghaffar 1993;Altman and Rovira 1989;Tu 1978;Fig. 5 Harikrishnan and Yang 2002). Their stimulated growth under the longer-term chlorimuron-ethyl application would make the soybean plants more easily suffer from root rot disease.…”

Development of Sclerotium rolfsii sclerotia on soybean, corn, and wheat straw, under different soil temperatures and moisture contents

“…In many instances, disease severity is a consequence of problems such as inadequate fertility (Rodrigues et al, 2002), incorrect pH, soil compaction, poor drainage, herbicide injury (Reichard et al, 1997;Harikrishnan & Yang, 2002) and high levels of nematode infestation (Rodriguez-Kábana et al, 1994). Correcting these problems is the first step towards disease management in soybean (Hartman et al, 1999).…”