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Strawberry Plasticulture - March 25, 2003 (No.2)
Vol. 4, No. 19 - Reports from the field today
A. Extension agent assists Alabama grower in identifying
anthracnose – since
last week we have been following with some concern a Camarosa plant
sample that was first brought to our attention (via the internet) by
Dan Porch, Alabama Cooperative Extension System, Blount County Office,
Oneonta, AL. Here are the two photos that Dan sent us on 18-Mar; Dan
also got these samples right into the Auburn
clinic for laboratory diagnosis the same day.
Fig. 1 Longitudinal section of Camarosa blossoms showing necrotic
tissues.
Fig. 2. Aerial view of blossoms exhibiting black spots.
This late afternoon (25-Mar) we have learned that this sample was
positive for anthracnose. There was some thought that this might
be somehow related to cold injury during the winter – this
does not seem to be the case. According to the grower, the problem
is confined to the Camarosa variety. Last Friday (21-Mar) he made
an application of Quadris + captan. In a situation like this, it
may be advisable to repeat this same application in 7 days. There
is some rainfall expected, and this makes it advisable to go with
the tighter 7 day interval. Since a frost is possibly expected this
weekend, the grower was concerned about the effects of sprinkling
(irrigation will cause anthracnose to spread), and wondered if row
covers would be better. Unfortunately, we have had some very unsettling
episodes with row covers in situations like this – it is possible
that the cover is an ideal way to spread the spores further! So,
we can hope that the cold event expected this weekend does not require
sprinkling. Also, the grower should reduce, if not omit N fertilization
for this week and possibly next. We appreciate Dan’s bringing
this to our attention. Please take note of today’s earlier
advisory to commence applications of Quadris + captan, or Cabrio
+ captan at 10% bloom (not later) for plants in which anthracnose
may be present.
B. Angular Leaf Spot
Fig. 3. Angular Leaf Spot (ALS) Symptoms – sample
from Clayton today. Control for Angular Leaf Spot is very difficult
to achieve. One producer at the Nash Co. Pre-harvest meeting on March
6th indicated that removal of the oldest leaves in late winter seemed
to help control the problem. Wet, cool conditions promote this disease.
No bactericides are labeled for ALS. Early application of registered
copper materials prior to rapid growth may reduce disease – see
Ag Chem Manual and read labels closely about potential phtotoxicity
from using coper fungicides (after Frank Louws, IPM Management Manual).
E. Barclay Poling, Small Fruit Specialist
Campus Box 7609
Kilgore Hall - Office 252
NC State University
Raleigh, North Carolina 27695-7609
919.515.1195
919.515.2505 (fax)
919.418.9687 (mobile)
web site:
http://intra.ces.ncsu.edu/depts/hort/berrydoc/
click HERE
to return to strawberry advisories page
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