Authors
L. E.
Sconyers
,
T. B.
Brenneman
, and
K. L.
Stevenson
,
Department of Plant Pathology
, and
B. G.
Mullinix
,
Experimental Statistics, University of Georgia Coastal Plain Experiment Station, Tifton 31794
ABSTRACT
Two microplot studies were conducted with peanut (Arachis hypogaea L.) in 2000, 2001, and 2002 to determine the effects of plant spacing, inoculation date, and cultivar on stem rot development caused by Sclerotium rolfsii Sacc., tomato spotted wilt incidence, and microclimate (temperature and relative humidity). Stem rot severity and incidence decreased as plant spacings were increased in 5-cm increments from 5 to 30 cm. Two cultivars with similar susceptibility but different growth habits were compared. Perhaps due to heavy irrigation and extensive vegetative growth, stem rot was similar for ‘Florida MDR-98’ and ‘Georgia Browne’. Plants inoculated later in the year (90 days after planting [DAP]) had less disease at harvest, but often developed more severe symptoms within the first week of inoculation than plants inoculated at 50 or 70 DAP. Canopy microclimate was different than ambient conditions for all treatments; however, differences among treatments were inconsistent and did not explain differences in disease among spacings. Generally, as plant spacing decreased and plant population increased, stem rot increased and tomato spotted wilt was reduced. These data demonstrate that the physical spacing between plants is a critical factor in disease development.
