Comparison of Fungicide Programs for the Control of Early Leaf Spot and Southern Stem Rot on Selected Peanut Cultivars1

Abstract

Azoxystrobin, tebuconazole, pyraclostrobin, chlorothalonil + flutolanil, and chlorothalonil fungicide programs were evaluated on selected peanut cultivars for the control of early leaf spot (ELS) and southern stem rot (SSR) in 2000, 2001, and 2002. A peanutcotton-peanut rotation was followed and the plots were irrigated as needed. Virugard and Georgia Green were planted in all 3 yr. The late-maturing line Southern Runner was planted only in 2000 and was replaced with Florida C-99R in 2001 and 2002. Since the ranking of fungicide programs for ELS and SSR control and yield response was similar over peanut cultivars, data for each variable in 2000, 2001, and 2002 were pooled. The • 0.34-kg ai/ha azoxystrobin and pyraclostrobin programs gave better ELS control than the season-long chlorothalonil standard in 1 yr. However, SSR control and yield response to pyraclostrobin was similar to the chlorothalonil standard. Significant reductions in SSR damage and higher yields were obtained with 0.34-kg ai/ha azoxystrobin program in all 3 yr. When compared to the chlorothalonil standard, the 0.47-kg ai/ha azoxystrobin program gave superior SSR control in 2000 and 2001, but significantly better ELS control and higher yield were obtained only in 2001. Tebuconazoletreated peanuts had similar ELS ratings to those recorded for the chlorothalonil standard and azoxystrobin programs in 2000 and 2001, but the ELS ratings for the former program were significantly higher in 2002. While tebuconazole reduced SSR damage compared with chlorothalonil alone, the azoxystrobin and chlorothalonil + flutolanil programs controlled SSR significantly better than tebuconazole in at least 1 yr. Also, the 0.34-kg ai/ha azoxystrobin program significantly increased yield above that of the chlorothalonil standard more consistently than did tebuconazole. Relatively few differences in disease control or yield response were noted between the two chlorothalonil + flutolanil programs, but both increased yield above that of the chlorothalonil standard. By maturing about 2 wk before Georgia Green, Virugard may have escaped some ELS and SSR damage, which may have contributed to its higher yield. There are indications that the late-maturing Florida C-99R has partial resistance to ELS but not SSR. Georgia Green proved more susceptible to both diseases than Virugard

Management of Leaf Spot Diseases of Peanut With Prothioconazole Applied Alone or in Combination With Tebuconazole or Trifloxystrobin

“…Tebuconazole and propiconazole have been widely used for disease control in peanut in the U.S. since 1994. Performance of tebuconazole compared to chlorothalonil has changed over the past ten years, with recent reports of tebuconazole being inferior to chlorothalonil in several experiments (Culbreath et al, 2005;Culbreath et al, 2006;Hagan et al, 2004;Stevenson and Culbreath, 2006). Populations of both C. arachidicola and C. personatum have become less sensitive to tebuconazole since previous characterizations in the late 1990s (Stevenson and Culbreath, 2006;Stevenson et al, 1999).…”

Development of an Inoculation Method for Quantifying Fungicide Residues on Peanut Foliage

“…Therefore, tank-mixes with other fungicides, such as propiconazole or chlorothalonil, are required for leaf spot control when flutolanil is used (Kemerait et al, 2003). Azoxystrobin, a quinone outside inhibiting (QoI) fungicide, has been shown to be active against both foliar and soilborne diseases (Grichar et al, 2000;Hagan et al, 2004). Fungicide programs utilizing tebuconazole consist of a calendar-based 4-spray block of applications; whereas, flutolanil and azoxystrobin are generally applied 60 and 90 days after planting (Kemerait et al, 2003).…”

“…Flutolanil, a benzanilide fungicide, is highly effective against S. rolfsii and R. solani (Csinos, 1987;Hagan et al, 2004), but has little or no activity against the leaf spot pathogens. Therefore, tank-mixes with other fungicides, such as propiconazole or chlorothalonil, are required for leaf spot control when flutolanil is used (Kemerait et al, 2003).…”

Chemical Control of Peanut Diseases: Targeting Leaves, Stems, Roots, and Pods with Foliar-Applied Fungicides

“…These formulations were thought to sift through the canopy ultimately arriving at the soil; however, control using these materials was costly and inconsistent. The registration of the flutolanil has provided producers with a more effective means of managing soilborne diseases (Hagan et al, 2004). Furthermore, the registration of tebuconazole and azoxystrobin, has greatly improved both stem rot and leaf spot management over the past decade Brenneman and Murphy, 1991;Grichar et al, 2000).…”

“…While many of the products currently on the market have activity against diseases caused by both foliar and soilborne pathogens, flutolanil was registered in 1995 and is only active against S. rolfsii and R. solani. Therefore it must be used in combination with products with leaf spot activity (Hagan et al, 2004). However, to effectively use any fungicide for management of soilborne pathogens, the technical difficulties of getting the fungicide to the lower stem and around the pegs and pods must be considered.…”