Vergara - 1976 - Physiological and morphological adaptability of ri

EPIDEMIULOCJY OF SOUTHERN CORN LEAF BLIGHT 403
Ooniclb Immz
I60
l4O
8O
4O
o 92 94 96 9s too
Fblutive humitity m)
3. Effect of relative humidity on sporulation of fielmmthospomanr
maydls race T on corn. Each entry repre~
sents the number of conidizvmm’ from l5 lesions afier l6
h: at 24"C.
*1 = number of eonidia with dc\v_ as found by
Nelson and Tung (Fig. 2). under otherwise sunila:
ctmditions
under similar conditions except ‘when dew was present. Nelson and Tung
(l973b) reported a mean number of 7‘) conidiafmml.
For simulation of this disease, a free water requirement for sporulation could
be misleading. It is conceivable that there might be periods without free water
but with RH above 94%. Therefore, a more appropriate criterion for sporulation
may be occurrence of RH above 94%.
FIELD STUDIES
During the summers of I971, 1972, and I973, the amount tifdisease and the rate
of increase of SCLB were monitored in a series of field plots. The research portion
of each one~aere plot consisted of 6.000 plants of Trns hybrid Pioneer
3306T planted at a density of approximately 20,000 plants per acres