The root rots (RR), caused by the
Fusarium spp., causes loss of seedling in the nursery that show, initially,
discoloration of the needles to a yellowish-green tone followed by apical curvature, wilt and the consequent
death of the seedling. The objectives of this work were to: a) define the most appropriate and efficient
method to detect
Fusarium spp. in
Pinus taeda seeds; b) verify if there is transmission of
Fusarium spp.
from seeds to
Pinus taeda seedlings; c) develop a descriptive scale to evaluate the severity of the RR in
Pinus taeda seedlings; d) evaluate the pathogenicity, aggressiveness and area under the disease progress
curve (AUDPC) of isolated
Fusarium subglutinans. For detection three treatments were applied to six lots
of
Pinus taeda seeds, bein four repetitions of 25 seeds: blotter test, paper card and selective medium. The
transmission was evaluated in seeds from six lots of
Pinus taeda during 60 days counting the percentage of
emerged plantlet (EP), non-germinated seeds (NGS) and from NGS seeds with
Fusarium spp. A descriptive
scale of grades was developed to evaluate the severity of RR in
Pinus taeda seedlings. The severity and
the incidence of the illness were evaluated at 7, 14, 21 and 28 days after the inoculation from
Pinus taeda
seedlings of six months of age. The pathogenicity, severity and incidence of twelve isolated
Fusarium subglutinans
obtained in the detection test. To test for pathogenicity and aggressiveness 13 treatments
with 15 replications were applied. The most sensitive detection method to detect
Fusarium spp. on
Pinus
taeda seeds was the selective medium; transmission was not observed of
Fusarium spp. from seeds to
the seedlings; the descriptive scale allowed evaluating the progression of RR symptoms; nine isolated of
Fusarium spp. were found to be pathogenic to
Pinus taeda seedlings, reproducing typical symptoms of RR,
being isolated L3R2, the most aggressive and that exhibited higher AUDPC.
