Peanut Growth Responses to Different Levels of Leafspot
1984
Teare, I. D. | Shokes, F. M. | Gorbet, D. W. | Littrell, R. H.
Peanut leafspot, a disease caused by Cercospora arachidicola Hori (early leafspot), and Cercosporidium personatum (Berk. and Curt.) Deighton (late leafspot) are the most destructive foliar pathogens of peanut (Arachis hypogaea L.) and occur each year in Florida in epidemic proportions. This research establishes a data base relating growth of 'Florunner' peanut to leafspot disease severity and can be used as an aid in evaluating other resistant lines. Five leafspot disease severity levels were applied to Florunner peanut during the 1982 growing season by spraying with five levels of chlorothalonil (tetrachloroisopthalonitrile) foliar sprays beginning 40 days after planting, and continuing on a 14 day schedule until harvest. The research was conducted at the Marianna Agricultural Research Center, on a Lucy fine sand (loamy, siliceous, thermic Arenic Paleudult). Disease severity levels were compared to peanut growth measurements of leaf area index (LAI), shoot weight (leaf and stem), root weight (lateral and tap root), sample pod weight, and total biomass during the pod fill period. Although ratings were made for early and late leafspot, late leafspot was the predominant foliar disease. The LAI, leaf weight, and lateral root weight were negatively influenced by invasion of late leafspot pathogens. A comparison of field pod yield to sample pod yield indicated that lower dosages of chlorothalonil were not effective in maintaining healthy pegs, and may have allowed early pod maturity and resulted in some shedding of pods.
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