Allelochemicals Biologica... - Name

NATURAL PRODUCT BASED FUNGICIDES 7
cides were applied to strawberries: fenhexamid (Elevate®, Arvesta, San Francisco,
CA) at 1.6 kg/H, fenhexamid + captan (CaptEvate®, Arvesta, San Francisco, CA) at
a low rate (3.9 kg/H) and a high rate (5.82 kg/H), azoxystrobin (Quadris®, Syngenta
Crop Protection, Greensboro, NC) at 0.56 kg/H, cyprodinil + fludioxonil (Switch®,
Syngenta Crop Protection, Greensboro, NC) at 0.8 kg/H, captan (Micro Flo Company,
Memphis, TN) at 3.4 kg/H, mylclobutanil (Nova®, Dow AgroSciences, Indianapolis,
IN) at 0.28 kg/H, pyrimethanil (Scala®, Bayer CropScience, Research Triangle
Park, NC) at 1.9 kg/H, fenhexamid at 1.68 kg/H + captan at 3.4 kg/H,
pyraclostrobin (Cabrio®, BASF, Research Triangle Park, NC) at 0.20 kg/H,
pyraclostrobin + boscalid (Pristine, BASF, Research Triangle Park, NC) at 0.62 kg/
H, boscalid (Emerald®, BASF, Research Triangle Park, NC) at 0..59 kg/H, and the
experimental fungicide, CAY-1 at 0.37 and 0.74 kg/H. Fungicide treatments were
applied every 7-10 days (or as soon after rainfall as possible) starting at or near fullbloom
stage and continuing until 1 week before harvesting ceased.
Berries were harvested twice a week throughout the entire season beginning on
January 30 and continuing until April 24 in 2003. Total fruit count and weights were
obtained for both marketable and cull fruits, along with average weight per berry and
percentages of marketable, physical cull, and diseased cull fruit per acre. Fruit were
separated into marketable and cull classes, with the culls being further divided into
physical (deformed or small fruit) culls and diseased culls. Diseases were identified
and counted on three occasions including berries with gray mold (B. cinerea), anthracnose
(C. acutatum), leather rot (Phytophthora cactorum), stem end rot (Gnomonia
comari), and other rots that occurred during the picking season. Plants were rated on
April 24, 2003 for incidence of foliar disease, number of dead plants due to anthracnose,
crown rot and plant vigor. Diseases were rated on a scale of 0-5; 0 plants
showed no leaf symptoms and 5 plants were completely defoliated. Plant vigor was
rated on a scale of 0-5; 0 were dead plants and 5 were extremely vigorous plants.
3. RESULTS AND DISCUSSION
Results from the bioautography studies suggest that chemically different populations
of microorganisms and plants can easily be distinguished by their characteristic “2D-
TLC fingerprint” and antifungal zone patterns (Wedge and Nagle, 2000). Thus, this
system represents a very useful technique for the identification and selection of unique
chemotypes from microbial isolates (Nagle and Paul, 1999) and plant extract(?)
collections.
Chromatographic properties such as relative polarity, UV absorbance, chemical
reactivity associated with each active metabolite provide valuable information that
allows for rapid dereplication of known or nuisance compounds. When strains of
different phytopathogenic fungi with dissimilar fungicide resistance profiles are
inoculated onto replicate bioautography plates prepared from any given extract
containing active metabolites, it is possible to visually observe distinct differences in
the sensitivity of each fungal pathogen to single metabolites. These differences in
pathogen sensitivity (fungicide resistance) can be observed by direct comparison of