August 5, 2005 Volume 4 Number 16
1. View from the Field
2. Phytophthora Root Rot in Soybean
3. Is Armyworm “Falling” into Your Field?
4. Soybean Aphid Data Collection Need!
5. Growing Degree Days In NYS
6. Clipboard Checklist
7. Contact Information
View From the Field
I’ve seen numerous western and
northern corn rootworms in late-planted continuous corn in Ontario
County. In Wyoming County, potato leafhoppers continue to be
difficult to find in alfalfa. In several alfalfa fields in Ontario
County (new seedings and established stands), leafhoppers are
abundant but below threshold. Mike Stanyard (NWNY Team) reports
that he has seen fungal pathogens causing soybean aphid mortality
in Wayne County. With the recent hot, humid weather and heavy
morning dews, conditions have been ideal for development of
these fungal pathogens. Watch here for photos next week! Reports
from Cayuga County indicate that soybean aphids are in decline
many places thanks to predators. Also in Cayuga County, grasshopper
damage is prevalent, but below economic levels. Nancy Glazier
(NWNY Team) checks in with a report from the soybean fields
she is scouting in Orleans County: One field has 600 to 800
aphids per plant and numbers are still on the rise. Downy mildew
is present in many fields.
Soybeans: During a Soybean TAg
meeting Thursday night we observed soybean aphids that ranged
for 10 to 50 per plant. This is well below threshold. There
were also several lady beetles in the field feeding on the aphids.
A few of the growers stated that they had several grasshoppers
in a few of their bean fields. They indicated that the grasshoppers
were feeding in the leaves and showed about 20 % damage. Soybeans
can withstand up to 35 % leaf feeding without losing yield.
The following is a picture of a grasshopper on the soybeans:
Phytophthora Root Rot in Soybeans
Julie Stavisky, NYS IPM
Some areas of plants affected by
Phytophthora root rot (PRR) have been seen in soybean fields
recently. The symptoms include significantly rotted roots, dark
brown or black scars on the stem from the soil line up, and
wilting followed by death of leaves at the top of the plant.
A photo of the stem injury is shown in the following link:
PRR is caused by a water mold. In a dry year like this season,
the disease is most prevalent in low areas of fields and fields
with poor drainage due to compaction or soil type. In a wetter
year, PRR can affect plants even in well-drained soils.
If a large area of a field is severely affected or killed
by the disease, PRR may have an impact on yield. In less severe
situations, the ability of soybean plants to compensate for
yield when an occasional plant dies will typically prevent significant
Many common crop management practices prevent PRR from becoming
a serious problem in soybeans. When PRR is of concern, management
strategies include improving field drainage, planting resistant
varieties, and rotating to another crop.
Is Armyworms “Falling” in to your fields?
Ken Wise, NYS IPM
Lewis and Jefferson counties have
been reporting some corn fields with armyworm damage. Most likely
this time of the year it the pest would be fall armyworm. Fall
armyworm larvae are green, brown, or black about 1/8 inch to
1 ý inches long and have a dark head capsule usually marked
with a pale, but distinct, inverted "Y." Along each side of
its body is a longitudinal, black stripe, and along the middle
of its back is a wider, yellowish-gray stripe with four black
dots on each segment. Larvae are active at night, but can be
seen feeding on overcast days. Larvae will hide under the canopy
of the grass during the day. You will need to be aware that
armyworms can move from field to field every quickly. Fall armyworms
can show up starting in late June. This armyworm seldom causes
economic losses in corn. If there are sufficient numbers and
damage is present, an insecticide could be justified. Treat
only the affected area and a 20 to 40-foot border around the
infestation. (Note: the corn maybe too tall to treat with an
insecticide). Rarely does a whole field need to be treated for
armyworm. Larger armyworm larvae, greater than 1.5 inches long,
are much more difficult to control. These large larvae are more
tolerant of insecticides, reducing the effectiveness and economic
viability of this option.
Soybean Aphid Data Collection Need!
Keith Waldron, NYS IPM
Soybean Aphid threshold values
for SBA populations have not been extensively tested in NY.
More field data is needed to establish and validate practical
• If you have soybeans at the early
pod fill growth stage (or earlier), Soybean aphid populations
have reached the 250 per plant recommended threshold and you
plan to treat the field with an insecticide….
We Need Your Help!
Side by side field trial data with insecticide treated vs.
non treated check strips is critical to refine our New York
threshold recommendations for managing soybean aphids.
If you have fields meeting the conditions described above
and would like to participate..
Please contact your local Cooperative Extension office or
the NYS IPM Program office at 315 - 787 - 2432, firstname.lastname@example.org.
-Soybean aphid population assessments
- average number of SBA's per plant
-Soybean variety, growth stage at time of treatment
-Insecticide used, rate of application
-Yield information, date of harvest
-Field Location, grower contact information
PLEASE RECORD THE FOLLOWING:
Grower contact information
Field location (GPS if available)
Average number of SBA's per plant pre-treatment
Soybean growth stage
Insecticide Treated Not Treated with Insecticide
Rate of application
Date of harvest
Growing Degree Days in NYS
March 1 - August 4,
Base 50 F
Keith Waldron, NYS IPM
• Maintain crop
production activity records by field, including harvest date,
pesticides used, nutrient inputs including manure, etc.
Alfalfa & Hay:
• Continue monitoring for potato leafhopper- harvest early
or spray on basis of need.
• Monitor for diseases and record information on type and
location for future cropping decisions.
• Monitor for foliar and stalk diseases, nitrogen and other
nutrient deficiencies, European corn borer, weeds.
• Monitor corn rootworm adults at silking.
• Monitor for soybean aphid, soybean rust, foliar diseases.
• Continue livestock facility sanitation management (manure,
feed bunks and storage areas, waterers, etc.). Cleaner, less
• Mow around facilities to minimize rodent habitat.
• Monitor young stock for cattle lice and mange mites
• Check condition of pastures and animals on pastures
- Evaluate need for face fly and stable fly control measures
- Check and clean pasture water supplies.
Julie Stavisky: IPM Area Educator, Livestock and Field Crops,
Phone: (315) 331-8415
Fax: (315) 331-8411
Keith Waldron: NYS Livestock and Field Crops IPM Coordinator
Phone: (315) 787 - 2432
Fax: (315) 787-2360
Ken Wise: Eastern NYS IPM Area Educator: Field Crops and Livestock
Phone: (518) 434-1690
Fax: (518) 426-3316