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ARS Home » Southeast Area » Tifton, Georgia » Crop Genetics and Breeding Research » Research » Publications at this Location » Publication #186008


item Maas, Andrea
item Dashiell, Kenton
item Melouk, Hassan

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2006
Publication Date: 4/25/2006
Citation: Maas, A.L., Dashiell, K.E., Melouk, H.A. 2006. Planting density influences disease incidence and severity of Sclerotinia blight in peanut. Crop Science. 46:1341-1345.

Interpretive Summary: Sclerotinia blight in peanut causes economic losses to growers in most peanut growing regions in the United States. Limited forms of chemical control are available as well as being costly which makes natural forms of host plant resistance an attractive alternative. Multiple methods of disease assessment for the field have been utilized in the selection of resistant cultivars. The goal of this study was to optimize the assessment process. Frequency of diseases occurrence and severity of the disease were assessed at different plant spacings. Through this work it was determined that frequency of disease occurrence and date of initiation would assist the plant breeder in potentially selecting plants earlier in the cultivar development process.

Technical Abstract: Sclerotinia blight caused by Sclerotinia minor Jagger has become one of the major limiting factors in peanut (Arachis hypogaea L.) production. The objectives of this research were to evaluate: 1.) the effects of plant spacing on disease incidence and severity of Sclerotinia blight in peanut research plots, 2.) the level of apparent resistance at different seeding rates, 3.) determine which methods would produce clearest selection criteria in space planted breeding plots. Four peanut cultivars, ‘Tamspan 90’, ‘Southwest Runner’, ‘Okrun’, and ‘Flavor Runner 458’, were evaluated in field plots at four plant spacings, (6.1 cm, 15.3 cm, 30.3 cm, and 45.7 cm), in 2003 and 2004. Plots evaluated for date of initial disease onset indicated that in the southern great plains region this may not be a predictor of final disease present in the field. Disease incidence and severity tended to increase with increased plant spacing in susceptible genotypes at a significance level of p=0.05. Calculations of disease severity that included all plants present in the plot relative to total diseased stems produced the highest level of significant differences (p=0.Ol) at the widest plant spacing between susceptible and resistant genotypes. Final disease incidence provided significant (p=0.05) differences with the least labor required to evaluate the material relative to other methods of disease determination.