Phytophthora shuck and kernel rot infection usually started at the ste
m end of the pecan fruit and progressed distally to encompass the enti
re shuck within 4 to 6 days. A distinct margin developed between dark
brown necrotic tissue and healthy green tissue during rotting of the s
hucks. Phytophthora cactorum was isolated from the rapidly rotting pec
an fruit. Two to three weeks after the symptoms appeared, the diseased
shucks dried and stuck tightly to the shell. The seed coat of the ker
nel turned dark brown and the endosperm rotted. The new disease of pec
an was first observed during September 1988 on maturing pecan fruit in
central Georgia in the vicinity of the town of Byron where growers es
timated losses of 50% or greater in some orchards. In south Georgia ne
ar the cities of Albany and Cordele, the disease was present but less
severe. The causal agent was identified as P. cactorum and deposited w
ith ATCC as isolate B1, ATCC No. 66186. Laboratory and field inoculati
ons of nut clusters using the B1 isolate produced typical symptoms obs
erved in nature. Symptoms of the disease were observed in 13 orchards,
and the pathogen was isolated from the soil of 10 of these orchards i
n south and central Georgia.