Clinic update: August samples at the diagnostic clinic
We have had a number of interesting
submissions to the plant diagnostic
clinic during August. What follows is a
summary of some of the samples we have
worked with over the past month.
We have had some tree samples with
a large variety of issues. While many of
the oak wilt samples we have received
have come in to the lab later than they
have in the past, several samples have
been confirmed during August and early
September. Positive samples have come
from the St. Louis area, central Missouri
and Adair county. Other oak samples
have included Tubakia leaf spot (fewer
positives so far compared to last year),
jumping oak gall injury (samples have
come in all summer), and Botryosphaeria
twig canker (Pin oak with dead branch
tips). White pine samples had bagworms,
a bark beetle infestation and pine wood
nematode infection (white pine is
normally considered resistant to pine
wilt). We had a scotch pine sample that
was also positive for pine wilt nematode.
Several Colorado blue spruce samples
had bagworms as well as Rhizosphaera
and Stigmina needlecasts. Multiple
magnolia samples have had magnolia
scale. In addition to the scale, extensive
sooty mold development was present on
the magnolia samples. The clients often
complained that the scale were attracting
bees or other insects to the area. Several
other trees have been submitted with
foliar diseases. A short list includes
willow with Cercospora leaf spot, horse
chestnut with Guignardia blotch, elm
with black spot, dogwood with powdery
mildew and Phyllosticta leaf spot, and ash
with Phyllosticta leaf spot. Ornamental
plum twigs had block knot infection,
juniper had sapsucker injury, and pecan
had a spittlebug infestation.
We have also had a limited number of
other ornamental samples. Winterberry
had a Cercospora leaf spot, peony had
an Alternaria leaf spot, and coneflower
had powdery mildew. Houseplants from
a couple different locations have been
submitted with severe sunburn after
being moved outside temporarily during
the middle of overcast days.
Finally we have had a number of
fruit, herb and vegetable submissions.
Several pepper submissions have been
received. Pepper samples have had
bacterial leaf spot, blossom end rot,
and Southern blight. Tomato samples
have also included bacterial leaf spot,
anthracnose, bacterial canker, early
blight, Septoria leaf spot, Fusarium wilt
and spider mites. Pumpkin and squash
samples have included Fusarium crown
and root rot, bacterial spot (on leaves and
fruit), as well as bacterial soft rot and
Fusarium rot of fruit. A recent cucumber
sample was the first cucurbit downy
mildew sample confirmed this year.
Finally, we confirmed Fusarium wilt on
basil and anthracnose on raspberry.
Sample submission can provide you
with an accurate diagnosis to allow you
to manage your plant problems, as well
as allow us to provide comprehensive
updates in the newsletter.