W. D. Branch

Disease and Insect Assessment of Candidate Cultivars for Potential Use in Organic Peanut Production

Abstract Interest in organic peanut (Arachis hypogaea L.) production is increasing in the United States. Disease and insect resistant cultivars will be needed to meet the challenge of producing peanuts without conventional pesticides. No-fungicide and no-insecticide field trials were conducted under irrigation four consecutive years (2003–06) at the University of Georgia, Coastal Plain Experiment Station to evaluate peanut genotypes for pest resistance. The most important foliar peanut diseases in the southeast are tomato spotted wilt (TSW) caused by Tomato spotted wilt virus and both early and late leafspots caused by Cercospora arachidicola Hori and Cercosporidium personatum (Berk. & Curt.) Deighton, respectively. Two of the most important insect pests on peanut are tobacco thrips (Frankliniella fusca Hinds) and potato leafhopper (Empoasca fabae Harris). Results from these no-fungicide and no-insecticide field trials showed significant differences (P ≤ 0.05) in pest resistance among advanced Georgia bre...

Field Test Results Versus Marker Assisted Selection for Root-Knot Nematode Resistance in Peanut

ABSTRACT A common set of 12 advanced Georgia peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) breeding lines that were derived from ‘COAN’ cross combinations were compared with three check cultivars for root-knot nematode (RKN) [Meloidogyne arenaria (Neal) Chitwood race 1] resistance. These 15 genotypes were grown in RKN populated field tests using a randomized complete block design with three replications for two years (2011 and 2012). Two molecular markers (SCAR 197/909 and SSR-GM565) used for marker assisted selection (MAS) did not agree with low gall ratings and high pod yield for four out of the 15 genotypes (26.7%). The results were the same each year with the same four field RKN-resistant genotypes being incorrectly identified as susceptible (false negatives) by both markers. Reciprocal cross combinations involving field resistant parents showed one-gene difference between MAS resistant × MAS susceptible in F1 and F2 populations. The lack of accuracy differentiating resistant RKN breeding...

Field Evaluation of Virginia-Type Peanut Cultivars for Resistance to Tomato Spotted Wilt Virus, Late Leaf Spot, and Stem Rot

Abstract Susceptibility to viral and fungal diseases is a major factor limiting profit in the production of virginia-type peanuts (Arachis hypogaea L.) in the South Carolina coastal plain. Field te...

New Sources of Cylindrocladium Black Rot Resistance among Runner-Type Peanut Cultivars

Abstract Cylindrocladium Black Rot (CBR) caused by Cylindrocladium parasiticum Crous, Wingfield, & Alfenas syn. C. crotalariae (Loos) Bell & Sobers is a major disease problem in southeast U.S. pean...

Evidence for a Second RKN Resistance Gene in Peanut

ABSTRACT Root-knot nematode (RKN), [Meloidogyne arenaria (Neal) Chitwood race 1] can result in highly significant yield losses in peanut (Arachis hypogaea L.) production. Fortunately, very high levels of RKN nematode resistance have been identified and incorporated from wild species into newly developed peanut cultivars. In 2011-12 at Tifton, GA, a field site was artificially inoculated with M. arenaria race 1. A susceptible cultivar was used to uniformly increase the peanut-specific race 1 nematode population during the summer and fall; whereas, hairy vetch (Vicia villosa Roth) was used for the same purpose each winter as a susceptible cover crop. During 2013 and 2014, space-planted F2 and F3 populations from cross combinations involving A. hypogaea susceptible × resistant parental lines derived from ‘COAN’ were evaluated, respectively. Several past inheritance studies had suggested a single dominant gene, Rma, controlled the resistance. However in this study, the occurrence of a second recessive gene (r...

Revolute-Leaf, a New Completely Dominant Mutant in Peanut

ABSTRACT A Revolute-Leaf mutant plant was discovered in an advanced Georgia peanut (Arachis hypogaea L.) breeding line, GA 112702. The mutant had leaf margins that curve downward on each of the fou...

Stem Rot (White Mold) and Tomato Spotted Wilt Resistance among Peanut Genotypes

ABSTRACT Stem rot, also known as white mold (WM), caused by Sclerotium rolfsii Sacc., and tomato spotted wilt, caused by Tomato spotted wilt virus (TSWV), are two major disease problems in Georgia ...

Occurrence and Inheritance of a Puckered-Leaf Shape in Peanut1

Abstract An abnormal puckered-leaf shape was recently found in the cultivated peanut (Arachis hypogaea L.). Upon crossing this true-breeding genotype between and within both subspecies, inheritance data indicated two genes with epistatic interaction controlled this unusual trait which resembles tobacco thrips (Frankliniella fusca Hind) injury on peanut leaves. No maternal or cytoplasmic effects were detected among progenies from reciprocal hybridization. Subsequent allelism tests also detected no difference between the two similar occurring puckered-leaf mutants that were independently found in different genetic lineages. A new gene symbol, puc1 Puc2, for the puckered-leaf shape is being proposed to distinguish it from the narrow leaf gene, nl, as previously reported.