J. Juzwik et al., YU013 23ACQUISITION OF OPHIOSTOMA-QUERCUS AND CERATOCYSTIS-FAGACEARUMBY NITIDULIDS FROM O-QUERCUS-COLONIZED OAK WILT MATS, Plant disease, 82(2), 1998, pp. 239-243
Field experiments were conducted to determine whether the frequency of
Ceratocystis fagacearum and Ophiostoma quercus propagule acquisition
by nitidulids visiting oak wilt fungal mats is affected by the presenc
e of O. quercus on the mats. Augmentation sprays with O. quercus were
used to achieve different levels of mat colonization by that fungus. T
he extent of colonization by O. quercus 7 to 14 days after spraying wa
s greatest for postmature mats with open cracks (>0.5 cm) observed on
the spray date (P < 0.02). Specifically, all six subsamples assayed pe
r mat for 16 of 18 open, O. quercus-sprayed, postmature mats yielded O
. quercus. The frequency of nitidulids with O. quercus was also highes
t (83%) for those collected from O. quercus-treated, postmature mats t
hat were open on the spray date. The frequency of nitidulids with viab
le C. fagacearum (88%), however, was also greatest for beetles from th
e postmature mats. Thus, O. quercus colonization did not affect vector
acquisition of C. fagacearum from the mats. In addition, O. quercus v
ectored by nitidulids probably does not result in natural biological c
ontrol of overland transmission of C. fagacearum at fresh wound surfac
es on healthy oaks, as previously suggested.