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Crop
Wednesday July 17, 2013
Early fields are at R-1 to R-2, which is when the immature bud elongates 0.5 to 2.0cm above the nearest
leaf attached to the stem. Later fields are progressing and are at V-14.
Lygus bugs and Banded Sunflower Moth emergence is underway. Both of these insects are not a
problem at the current crop stage, and the optimum time for insecticide control is R-5.1. The economic
threshold for lygus bug is one adult Lygus per nine heads and1 adult moth per 100 plants for banded sun-
flower moth. Despite no insecticide being registered for the control of Banded sunflower moth, the optimal
time to spray is at R-5.1, corresponding with the optimal time for lygus bugs.
Sunflower Bud Moth larvae have started to hatch. The adults deposit eggs on the terminals of immature
sunflowers, the receptacle of mature sunflowers and in leaf axils. The hatched larvae begin to tunnel
creating the characteristic clue of black frass (insect excrement) surrounding the entrance hole. Although
activity is noticeable, Sunflower Bud Moth does not usually cause economic damage and there are no
control options available.
The optimum timing for control of seed damaging insects is R-5.1 or 10% flowering.
REMINDER:
Producers are encouraged to take the appropriate steps to reduce risk to honey bees when spraying
insecticides. This is for the benefit of both sunflower growers and beekeepers. Important steps include;
1. Scout fields for seed damaging insects and beneficial insects, only apply insectides if necessary.
2. Spray in the evening when honey bees have returned to the hive and communicate with bee
keepers.
3. Select insecticides that provide effective control of the targeted pests while minimizing impact on
bees.
4. Communicate with beekeepers in your area.
Honeybees can increase both the number and weight of sunflower seeds through increased pollination.
See attached the full article from provincial entomologist, John Gavloski.
MB Sunflower Crop Report
NATIONAL SUNFLOWER ASSOCATION OF CANADA
Manitoba Sunflower Surveillance Survey 2013 CanadaSunflower.com
Insects
Figure 1. Adult lygus bugs vary from light
green to dark brown and have a distinctive ‘V’ on
the wings.
“Producers are encouraged to take the appropriate steps to reduce risk to honey bees when spraying
insecticides. This is for the benefit of both sunflower growers and beekeepers.”
Figure 2. Adult Banded Sunflower Moths
congregate in ditches during the day. The best
time to scout is during the evening.
Figure 3. Pollinators are busy in flowering fields.
BEE-friendly; pay attention to timing and
insecticide choices.
Wednesday July 17, 2013
Downy Mildew (figure 1) continues to be noted in fields around the province. Infected plants samples are
being analyzed to identify the race of downy mildew to ensure that the seed industry is abreast of the
prevalent races. The disease produces symptoms which include a lighter green color along veins on leaves
and a thickened, club like root. Some fields have up to 15% infection of plants. There are no control op-
tions for later infection of downy mildew.
Sunflower Rust pustules have not yet been noted. Continue to monitor for the brown pustules as the
disease may still develop if we receive more rains and heavy dews. A fungicide application is most
economical when disease severity is 1 percent on the upper four leave prior to or during flowering.
The incidence of Sclerotinia basal rot (figure 3) continues to increase, however levels remain low on av-
erage.
Despite the presence of basal rot, the incidence of mid-stalk rot is very low. This may be an indication
that the level of spores in the air is low. However, there have been a few precipitation events recently that
may cause for some infection.
It is currently hard to predict the risk for sclerotinia head rot in flowering fields. Despite some areas
receiving rain, significant soil moisture is required for the sclerotia bodies to germinate and release spores.
Manitoba Sunflower Surveillance Survey 2013 CanadaSunflower.com
Figure 1. Sunflower planted affected by Downy
Mildew. Underside of leaves show white, powdery
mildew.
Disease
Figure 3. Wilted plants like the middle sunflower
plant above, often contains a basal lesion that
girdles the stem reducing water uptake.
R-2 R-3 R-4 R-5.1
Figure 2. Aecial cups on underside of sun-
flower leaf.