Effects of Reduced Tillage, Resistant Cultivars, and Reduced Fungicide Inputs on Progress of Early Leaf Spot of Peanut (Arachis hypogaea)

Abstract

Field experiments were conducted in 2000 and 2001 on Georgia Green, Florida MDR-98, and C-99R peanut (Arachis hypogaea) cultivars in Tifton, GA, to determine the effects of tillage practices on early leaf spot (Cercospora arachidicola) epidemics under standard fungicide regimes and fungicide regimes with fewer applications. Leaf spot epidemics were suppressed in reduced tillage (strip-till) plots compared with conventional tillage plots and were suppressed in MDR-98 and C-99R cultivars compared with the standard runner-type cultivar, Georgia Green. Within tillage and cultivar combinations, leaf spot intensity typically was lower in plots treated with fungicides at standard intervals (seven total applications) than in those treated at extended intervals (four total applications). However, in most cases, leaf spot control in extended interval treatments in the strip-till system was comparable to that in the standard interval treatments in conventional tillage. Based on these results, the number of fungicide applications could be reduced without compromising control of leaf spot when reduced tillage is used, especially if combined with moderately resistant cultivars. Suppression of leaf spot epidemics in the strip-till plots did not coincide with higher yields in either year. In 2001, yields were lower in strip-till plots than in conventional tillage plots. Yields were typically higher in the cultivar C-99R than in Georgia Green, regardless of the tillage treatment.

Evaluation of New High Oleic Virginia-Type Peanut Cultivars for Disease Tolerance, Yield, and Quality

“…Due to slightly higher disease tolerance compared to Bailey, good agronomic characteristics, high yield and quality under a variety of growing environments, and the presence of the high-oleic trait, Sullivan is an excellent cultivar for Virginiatype peanut production in the Virginia-Carolina region. A lack of yield response to higher-input fungicide programs for Sullivan and Bailey demonstrates the value of incorporating disease resistance/tolerance in peanut breeding programs (Wynne et al, 1991;Monfort et al, 2004;Cantonwine et al, 2006;Chapin et al, 2010). Furthermore, high yields and net returns of Sullivan regardless of fungicide program suggests further reducing fungicide inputs during production of this and other disease resistant/tolerant cultivars may be possible under low to moderate disease pressures as suggested by previous studies (Phipps, 1993;Cantonwine et al, 2006;Woodward et al, 2010Woodward et al, , 2014.…”

“…As new cultivars with partial disease resistance are developed and released, the need for costly fungicide inputs to produce acceptable yields has decreased (Monfort et al, 2004;Cantonwine et al, 2006). The Virginia-type cultivar Bailey was released in 2011 (Isleib et al, 2011), and the partial resistance of this cultivar to diseases including late leaf spot, CBR, and Sclerotinia blight, as well as good yield and quality characteristics, has made this the cultivar of choice for growers in the Virginia-Carolina region.…”

“…Weather-based disease advisory programs have reduced the number of fungicide sprays required for control of peanut diseases, thereby reducing total fungicide costs in peanut production, and leaf spot and Sclerotinia advisories for peanut are frequently utilized by peanut producers in the Virginia-Carolina region (Cu and Phipps, 1993;Phipps et al, 1997;Langston et al, 2002). Some studies have found that reducedinput fungicide programs can effectively manage diseases in cultivars with partial disease resistance or tolerance and result in overall greater profitability compared to standard, high-input fungicide programs (Monfort et al, 2004;Cantonwine et al, 2006;Woodward et al, 2014). Ultimately, weatherbased fungicide advisories may need to be revised to account for the higher levels of disease resistance in newer peanut cultivars, and there may be potential to further reduce fungicide inputs in peanut production.…”

Interaction of Tillage System and Irrigation Amount on Peanut Performance in the Southeastern U.S

“…While not always increasing yield, the benefit through changes in insects populations (Olson et al, 2006), weed species shift and pressure Price et al, 2007), and reduced disease pressures (Monfort et al, 2004;Wright and Porter, 1991b) illustrates that producers will seek conservation systems to fill specific needs in their cropping systems. This is evident in adoption rates of conservation tillage which stands around 30% (J. Beasley, personnel communication) in the SE U.S. A linkage to increased water use efficiency could increase adoption of conservation tillage in peanut, but perhaps more importantly provide non-irrigated growers a risk mitigation tool not previously considered.…”

Reduced Tillage Practices for the Southwestern US Peanut Production Region

“…Oklahoma producers have increased their adoption of strip tillage (ST) and NT systems in peanut production as a means of reducing costs and conserving soil resources, but the literature contains mixed reports on the effect of conservation tillage on disease and yield (Grichar andBoswell, 1987, Jordan et al, 2003;Monfort et al, 2004). Monfort et al (2004) observed that reduced tillage practices, like ST, may help with foliar disease management in peanut, especially when ST is used in combination with moderately resistant cultivars. They observed a delay in leaf spot development with reduced tillage.…”