Jm. Byrne et al., INFLUENCE OF DEW PERIOD AND TEMPERATURE ON FOLIAR INFECTION OF GREENHOUSE-GROWN TOMATO BY COLLETOTRICHUM-COCCODES, Plant disease, 82(6), 1998, pp. 639-641
Effects of temperature, duration of leaf wetness, and leaf position on
foliar infection of greenhouse-grown tomato (cv. Bonnie Best) by Coll
etotrichum coccodes were determined by inoculating plants with C. cocc
odes (5.0 x 10(5) conidia per ml) and keeping them in a dew chamber fo
r 0, 4, 8, 12, 16, 20, or 24 h of wetting at 15, 20, or 25 degrees C.
One week after inoculation, leaf disks were placed on the surface of a
n amended medium on which colonies of C. coccodes were compact and eas
ily identified, and severity of infection was quantified after 4, 6, a
nd 8 days. There was no infection of plants incubated at 15 degrees C,
while plants kept at 20 or 25 degrees C had increasing numbers of col
onies when leaf wetness duration was extended beyond 12 and 8 h, respe
ctively. Leaf position had a significant effect, with leaves tending t
o increase in susceptibility as they age. After 24 h of leaf wetness a
t 25 degrees C, the mean number of colonies per leaf disk from top, mi
ddle, and bottom leaves was 23.8, 29.0, and 34.0, respectively.