ARS | Publication request: Effect of post-inoculation relative humidity on peanut infection by Sclerotinia minor

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2011
Publication Date: August 8, 2011
Citation: Brown, M.J., Melouk, H.A., Hunger, R.M. 2011. Effect of post-inoculation relative humidity on peanut infection by Sclerotinia minor [abstract]. Phytopathology. 101:S20.

Technical Abstract: Stems of six-week-old plants of the cv Okrun (susceptible to Sclerotinia blight) were inoculated with S. minor. Two post-inoculation humidity regimes of 100% RH were used. In the first RH regime, one inoculation chamber was kept open for the duration of experiment (DOE), and five were closed for durations of 1, 2, 3, 4, or 7 days post-inoculation (PI). In the second RH regime, one chamber was kept open for the DOE, and five were closed for durations of 12, 24, 36, 48, and 60 hour PI. No infection occurred in chambers opened for the DOE or closed for 12 hr. Closure for 24 hr resulted in 50–75% infection, and closure for 48 hr or more resulted in 88–100% infection. Lesions on infected stems were measured up to 7 days after inoculation to calculate area under lesion expansion curve (AULEC). Closure for 24 hr produced AULEC of 8.2–9.7 cm2, whereas significantly (P = 0.05) higher AULEC of 18.0–16.0 cm2 were obtained with closure of >48 hr. These findings indicate the importance of providing 100% RH for at least 48 hr post-inoculation to effectively quantify lesion expansion.