Influence of Digging Date and Fungicide Program on Canopy Defoliation and Pod Yield of Peanut (Arachis hypogaea L.)

Abstract

Abstract Although response can be variable and is dependant upon many factors, digging peanut as little as 1 wk prior to or 1 wk following optimum maturity can result in substantial reductions in pod yield. While growers often assume that harvest should be initiated prior to optimum maturity in fields with high levels of canopy defoliation, there is no clear threshold where gains in pod weight and grade are offset by losses due to pod shedding. Moreover, yield loss relationships for foliar diseases have not been characterized for modern virginia market-type cultivars. Determining interactions between digging date and peanut canopy defoliation would assist growers and their advisors in making more informed decisions on when to initiate harvest to avoid yield loss. Research conducted from 2004–2005 in North Carolina established a range of defoliation levels in a total of seven fields. Fungicides were applied on a bi-weekly schedule from early July through mid-September, or were applied two times in July, or were not applied. Plots were dug early, 6 to 12 days before estimated optimum maturity, or at optimum maturity, as determined by the hull-scrape method. Although interactions between digging date and fungicide program were found in some cases, digging date and fungicide program effects often varied independently. A general recommendation of the percentage of canopy defoliation justifying early digging to prevent yield loss could not be determined from this research. However, data from these experiments reinforce the value of controlling early leaf spot, late leaf spot, and web blotch with timely fungicide applications and the importance of digging at optimum pod maturation for more recently released virginia market-type peanut.