Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2002
Publication Date: 7/15/2002
Citation: MELOUK, H.A., JACKSON, K.E. EFFECT OF POST INOCULATION RELATIVE HUMIDITY ON REACTION OF PEANUT TO SCLEROTINIA MINOR. PHYTOPATHOLOGY. 2002. V. 92(6). P. S55. PUBLICATION NO. P-2002-0395-AMA.
Technical Abstract: Detached shoots (DS) from 8-wk-old plants of 'Okrun' (OK), and 'Southwest runner' (SW), a Sclerotinia-susceptible and -resistant peanut cultivars, respectively, were inoculated with Sclerotinia minor (Peanut Sci. 19:58-62). At 24 hours post inoculation (PI), one-half of the DS were subjected to a lower relative humidity (RH), and the other half remained at 100% RH. Lesion length (LL) was measured daily from 2 to 6 days PI. Disease incidence (DI) under the 100% RH for OK and SW was 96 and 98%, respectively. Disease incidence in both genotypes was reduced by about 40% under the low RH regime. Lesion length under 100% RH at day 6 PI for SW and OK was 47 and 64 mm, respectively. Reduction of LL at day 6 under low RH was 66 and 76% for OK and SW, respectively. Correlation coefficient between LL at day 6 PI and area under disease progress curve was 0.96 (P=0.0001). These data support field observations that occurrence of low RH immediately following onset of Sclerotinia blight infection results in a lower disease severity.