April 2020 - 20

PLANT HEALTH
one contains an active ingredient
in FRAC 7 and one in FRAC 11.
Thus, rotating between them would
NOT be an effective practice for
resistance management.
Mike Zemke and I are back
to doing trials after almost five
years away from it. Last year,
we did about 40 trials and have
increased our test space again for
2020. We conducted one trial on
cyclamen with Sclerotinia petal
blight early in 2019. Treatments
were: noninoculated and inoculated
controls, Astun (a FRAC 7
fungicide) at 17 ounces/100
gallons, Pageant Intrinsic (18
ounces), Orkestra Intrinsic (8
ounces), Broadform (6 ounces) and
Mural (7 ounces). Products were
applied once before inoculation
and twice afterward on a weekly
Product Black Spot
Broadform Excellent
Mural
Orkestra
Intrinsic
Pageant
Intrinsic
interval. Results in Figure 1 show
that Astun, Pageant Intrinsic,
Orkestra Instrinsic and Broadform
provided very good control, while
Mural was less effective.
There are a number of diseases
that react similarly to each of the
7/11 premixes. I will call
these their core competency
on foliar diseases - Alternaria,
Cercospora, Colletotrichum
(anthracnose), Cylindrocladium,
powdery mildew, rust and
Sclerotinia. The reaction is typically
very good to excellent control when
used according to their labels. In
a few cases, one of them works
better than the others. These are
shown in Table 3. There are a few
blank spaces in the table because
I was not able to find tests on this
specific disease.
Botrytis
Excellent
Downy Mildew
Not labeled
Very good/excellent Good/excellent Very good
Some/very good
Good/very good
Excellent
Some/excellent Very good/excellent Very good
None/excellent Very good/excellent Some/excellent
Table 3. Efficacy for 7/11 fungicides on various foliar diseases.
Excellent
Very good/
excellent
For the diseases in Table 3,
choosing one over another could
be meaningful. For instance,
Broadform is not labeled for downy
mildew. Black spot on rose control
appears best with Broadform or
Mural. Watch for a new premix
from Syngenta midyear; it will be
a premix of FRAC 3 and 7 and a
welcome addition to our tool box.
HOW DO YOU ROTATE WHEN
USING PREMIXES?
Despite the fact that each of the
premixes has two active ingredients
representing two different FRAC
groups, it is still a good idea to
rotate products. If you pick another
premix, you would be using four
different FRAC groups, which
should be ideal for resistance
management without adding
Myrothecium Phyllosticta
confusion to your job. Although
few of you seem concerned with
following labels correctly, rotating
may be the only legal way to
make sure a crop does not have
more than a legally mandated
maximum amount of a particular
product per season or year. Some
of the products do have maximum
application restrictions (including
Broadform, Orkestra Intrinsic and
Pageant Intrinsic).
If you are rotating for
miscellaneous leaf spots and
Botrytis, you could rotate
Broadform (7/11) and Palladium
(9/12). If, however, you are in
an outdoor nursery and have
both bacterial and fungal leaf
spot concerns, you could rotate
Orkestra Intrinsic (7/11) with
Junction (M1/M3). If you are in
an outdoor nursery without any
bacterial concerns, you can rotate
Concert II (3/M5) with Orkestra
Intrinsic (7/11). If you are growing
roses outdoors, you need to be
concerned with black spot, rust,
downy mildew and powdery mildew,
often all at once. Consider Mural
and something else altogether.
If what you really want is the best
π
SHIPPING SUPPLY SPECIALISTS
OUR LABELS ARE
TOP SHELF
propagation trays
with results
product for a specific combination
of diseases on a specific crop, you
may not be able to find a premix
already created. You will be making
you own tank mix to do your best
to manage disease losses and
pesticide costs.
CONCLUSIONS
Premixes save time and allow
the user to be less involved in
disease management. In the
case of premixes, you are making
use of manufacturer expertise;
in the case of tank mixing, you
(or a consultant) are becoming
the expert. Both are valid and
effective ways to approach disease
management in ornamental
production.
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20 APRIL 2020 GPNMAG.COM
A.R. Chase is plant pathologist at Chase
Agricultural Consulting LLC and can
be reached at archase@chaseresearch.
net. For more information, go to www.
chaseagri.com.
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April 2020

Table of Contents for the Digital Edition of April 2020
