|Holbrook, Carl - Corley|
Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2005
Publication Date: 12/15/2005
Citation: Brenneman, T.B., Holbrook Jr, C.C., Culbreath, A.K. 2005. Screening cultivars and advanced germplasm for multiple disease resistance [abstract]. In: Proceedings of the American Peanut Research and Education Society, July 11-15, 2005, Portsmouth, Virginia. 37:30.
Interpretive Summary: not required
Technical Abstract: Disease resistance is a high priority in peanut breeding programs. Over 120 runner and virginia genotypes from six programs were evaluated in Georgia in 2003 and 2004 for resistance to multiple diseases in an effort to further quantify resistance in released cultivars and facilitate selection of advanced lines. Greenhouse screens were used to assess susceptibility to peanut root knot nematode (Meloidogyne arenaria) and Cylindrocladium black rot (CBR) caused by Cylindrocladium parasiticum. Susceptibility of genotypes to root knot ranged from 1.2-4.8 on a 0-5 scale, with the only genotypes showing excellent resistance being those with known resistance genes such as Nematam. Root rot ratings from CBR ranged from 1.1-4.6 on a 1-5 scale, with some experimental lines being highly susceptible and some showing very good resistance. Replicated field plots with minimal fungicide sprays were used to assess susceptibility to tomato spotted wilt virus (TSWV), leaf spots (Cercospora arachidicola and Cercosporidium personatum), and stem rot (Sclerotium rolfsii). The environment was very favorable for fungal diseases both years and severe levels of disease developed. A wide range of susceptibility to stem rot was found with GA-02C, AP-3 and DP-1 being among the most resistant, with some genotypes, primarily virginia types, being highly susceptible. Mean length of individual disease loci ranged from 2.6-3 9.5 inches, with Georgia Green, the current industry standard being 18.6 inches. Leaf spot ratings ranged from 3.8-7.6 on the Florida 1-10 scale in 2003, and 4.9-9.4 in 2004 with Georgia Green being a 5.8 and a 7.4, respectively. Incidence of symptoms caused by TSWV was too low to be meaningful. Overall this was a good evaluation of a diverse set of genotypes. Some that perform well in other states may not be as suitable for widespread planting in the southeast due to the prevalence of different diseases. Other genotypes were very promising and will be evaluated in more detail. This information will be critical as breeders decide which genotypes to develop, and it will help production specialists prescribe levels of input based on the disease susceptibility of cultivars that are released.