July 13, 2006 Volume 5 Number 13
1. View from the Field
2. Fusarium Head Blight of Wheat Considerations for Harvest
3. Why Use Potato Leafhopper Resistant Alfalfa?
4. Soybean Aphid Update
5. Soybean Defoliators Do They Do Damage?
6. Barn Fly Populations On The Increase
7. Soybean Rust Update
8. Clipboard Checklist
9. Growing Degree Days in NYS
10. Contact Information
View From The Field
Ken Wise, NYS IPM
Western NY and Finger Lakes
Julie Stavisky, NYS IPM
This week at the Cornell University Research Farm in Valatie
potato leafhopper population were very high. In a second year field
I got 120 potato leafhoppers in 3 sets of 10 sweeps. The alfalfa
plants are showing the typical v-shaped yellowing at the tips of
the leaflets that indicates PLH damage. By contrast, PLH populations
at the SUNY Cobleskill Farm remain very low, i.e. 1 or 2 leafhoppers/10
sweep sample in 24 inch alfalfa.
While scouting the soybean sentinel plot in Columbia County I
found a few plants with soybean aphids (SBA) on them. The aphids
were hard to find and only 5 of 50 plants inspected had aphids (1-8
sba’s per plant) on them. I scouted the rest of the field and found
a few more plants with aphids but still well below economic threshold
of 250 SBA’s/plant. I did find this plant (see photo) with ants
tending the aphids. The ants protect the aphids from predators and
in turn the ants eat the aphid’s honeydew secretion.
There were also some Japanese Beetles feeding on the soybean
leaves. While beetle feeding can be conspicuous, plants can generally
tolerate up to 40 % damage and not affect the yield. (See article
Jeff Miller (Extension Educator: Oneida County) discovered a
field infected with Glume Blotch which is the same disease that
is called Stagonospora Nodorum Blotch on the leaves. On wheat heads
the lesions begin as either grayish or brownish spots on the chaff,
usually on the upper third of the glume. As lesions enlarge, they
become dark brown and the centers turn grayish-white in color as
tiny brown or black dots (pycnidia) develop within them.
Across western NY and the Finger Lakes, it has been a dull week
for soybean aphids and an active week for potato leafhoppers.
Fortunately, soybean aphid numbers have been below 75 aphids for
plants from all reports that I have heard and observations that
I have made. These encouraging observations come from soybeans
(mostly at or close to R1 growth stage) in Wyoming, Wayne, Seneca,
Ontario, and Onondaga counties.
Potato leafhopper (PLH) is a different story. Last Friday
in Cattaraugus County, we swept an alfalfa field at a TAg team meeting,
and the field was close to threshold. Some yellow V-shaped
areas on leaf tips were already visible. Harvest was just
a day or 2 away, so treatment with an insecticide was not necessary.
Nancy Glazier made similar observations at the farms participating
in the Yates County TAg team. In particular, new seedings
were under severe threat from PLH. One field that was 18 to
24 inches tall and close to being cut had over-threshold numbers
of PLH. On the same farm, two alfalfa fields - one planted
to PLH resistant alfalfa, the other non-resistant. Interestingly,
the same numbers of PLH were observed, but visual symptoms of damage
were considerably less in the PLH resistant alfalfa. In other
PLH news, Nancy observed only very few PLH in alfalfa (first re-growth)
in Livingston County. In Onondaga County, I also saw few PLH in
a mixed alfalfa/grass stand. For a review of PLH thresholds
and the sequential sampling plan, check out our brochure
Potato Leafhopper on Alfalfa Management Guide.
One field in Livingston County had numerous leaf blotch miners,
approximately 30-40% of the tips mined. Generally this insect pest
does not do much damage to alfalfa. Much of the recommendation for
other states suggest that the economic threshold for this insect
pest is right around 50% of the leaflets showing the serpentine
trails where the larvae has feed on the cells just under the epidermis
of the leaf. See picture below:
Fusarium Head Blight of Wheat - Considerations
Julie Stavisky, NYS IPM
Last week at the Cornell Seed Growers Field Day, Gary Bergstrom
reviewed for us the serious situation of wheat scab infestation
occurring across the wheat-growing areas of NY. We reviewed
an article earlier this season, and you may want to visit the
Wheat Scab Prediction Model
Wheat scab reduces yield by decreasing the number of viable kernels
and reducing test weight, but the more significant impact is that
the fungus in diseased kernels may result in the production of a
mycotoxin known as DON, or vomitoxin. A wheat head showing the salmon/orange
colored spores that indicate Fusarium head blight (scab) infection
is shown below.
Gary reminds us that it is critical for farmers to be scouting
their fields now, before harvest, to determine if wheat is heavily
infested. An infected head of wheat will have “tombstoned” kernels
(those that are small and shriveled), or chalky white kernels.
Seeing a salmon-pink color on the heads is another sign of infection.
Free testing of wheat for the vomitoxin is available at The Star
of the West Mill in Churchville, near Rochester. If scab is
present in a wheat field, Gary recommends turning up fans on the
combine to blow out small, lightweight kernels, and taking measures
to clean the wheat.
Why use Potato Leafhopper Resistant
Ken Wise, NYS IPM
Have you had problems with potato leafhoppers (PLH) in your alfalfa?
You know that large infestations of PLH in alfalfa can reduce the
plant protein by 5% and yield by a half ton per acre per cutting.
If you see V-shaped yellowing on the tips of the leaves you have
a good chance potato leafhopper has been in your alfalfa. If V-shaped
yellowing has appeared you have already lost protein and yield,
plus the alfalfa will have slower re-growth after harvest and increased
chance of winter kill. A good option for reducing losses to this
insect pest is to plant PLH resistant alfalfa. Research has shown
that potato leafhopper resistant alfalfa is consistently higher
in quality than susceptible cultivars with or without potato leafhopper
pressure. The benefits of PLH resistance are particularly obvious
in years with high PLH infestations, a situation that can be expected
at least once or more during the life of the typical alfalfa stand.
Some of the most recent releases of PLH resistant alfalfa are as
high as 85 percent resistant. (Note: a “ highly resistant” cultivar
is 50% or more of the plants are resistant.) The newer potato
leafhopper resistant varieties have comparable yields as susceptible
alfalfa. You will still need to monitor this alfalfa because resistant
does not mean that it is immune to the pest. In the first 3 to 4
weeks the young plants have not developed their resistance to PLH.
The resistance is the granular hairs that grow in the surface of
the leaflets. In the young plants these hairs do not become fully
functional until about a month of growth. For management information
check out our on-line IPM guide
IPM for Potato Leafhopper in Alfalfa.
Soybean Aphid Update
Keith Waldron, NYS IPM
Statewide monitoring for soybean aphids is being conducted through
volunteer efforts by many individuals participating in New Yorks’
Soybean rust sentinel site network. These individuals provide weekly
summaries of their findings. These reports and input from other
cooperative extension, crop consultant and agricultural professionals
working with soybean producers are summarized and posted to the
USDA soybean rust / soybean aphid
Soybean aphid populations have been slowly increasing but have
typically been at low to trace levels at most locations reporting
across the state. No economically significant populations have been
reported in any NY soybean fields so far this season. SBA populations
can be expected to increase in the next weeks should warm temperatures
continue. A few reports indicate finding winged soybean aphids.
Natural enemy populations such as lady bird beetles have begun to
increase in many areas. Fields are generally at the V6 to early
Soybean Defoliators: Do They Do Damage?
Ken Wise, NYS IPM
Japanese beetle and Mexican bean beetle are the main defoliators
of soybeans in NYS. While they are minor pests, defoliation of soybeans
sends up many red flags by growers. The question normally is how
much leaf defoliation is too much in soybeans? The good thing is
that soybeans can withstand much defoliation without losing yield.
The soybean defoliation threshold is 35 percent of leaf are eaten
or missing from V1 to just before bloom. During blooming through
pod-filling stages, the threshold is 20 percent defoliation. The
following pictures are a guide that depict 10, 20, 30 and 40 percent
10 percent defoliation
20 percent defoliation
30 percent defoliation
40 percent defoliation
(Source: Purdue University Field Crops Pest Management Manual,
Populations on the Increase
Keith Waldron, NYS IPM
Warm temperatures and summer rains provide two ingredients that
can lead to a rapid increase in house and stable fly populations
- heat and moisture. Add undisturbed organic matter such as spilled
feed / silage, straw or soiled bedding and conditions are quite
favorable for a potential booming increase in house and stable fly
The Cornell Veterinary Entomology summer research crew (Colleen
Strong, Joy Tomlinson, Kay Russo, and Meaghan Pimsler) reports house
fly numbers appear to have dropped this week, although stable fly
counts rose significantly demonstrating the highest populations
they have seen on and around herds in the central NY (Finger lakes)
region yet this summer. The continued storm fronts seem to
be bringing in the stable flies. Trends in the stable fly
populations are being monitored on three local dairy farms (within
1 hour drive of Ithaca) using adhesive fly traps strategically placed
throughout the pastures. On one of the farms during the week
of 6/26 there was an average of 16 stable flies caught by the traps.
On the following week, the week of 7/3, the average jumped up to
127 stable flies, representing a significant increase in stable
fly populations. This same drastic increase was observed on
the other two dairy farms as well. It is speculated that the
large stable fly populations will persist for the next couple of
weeks at least. Horse flies on a local horse farm peaked about
a month ago and seem to be causing fewer problems now.
Now would be a good time to walk barns with an eye for evaluating
fly populations and the effectiveness of sanitation efforts.
Recall that each female house fly can lay between 100 and 150
eggs in each of the 4 - 6 batches of eggs produced over her 3+ week
lifetime. At a constant temperature of 86 F, house fly eggs can
hatch in 10 hours, go through their maggot stages in 5-6 days, pupate
and emerge as adults in another 4-5 days. Total time egg to adult
as few as 9 - 11 days.
Potential for population growth? One study showed that 25,000
to 40,000 stable and house flies could develop from bedding of a
single calf hutch during the summer. Under favorable environmental
conditions it is easy to see how fly populations can explode in
a very short amount of time.
Shutting down fly production relies heavily on cultural practices
that eliminate conditions favorable to fly breeding. Since house
flies and stable flies both breed in moist undisturbed organic matter
such as spilled feed, moist hay, wet grain, and manure-soiled bedding
eliminating these conditions on a regular schedule reduces fly population
growth by minimizing conditions favorable to successful fly breeding.
Cornell's Veterinary Entomology program reminds us that sometimes
innocuous routines such as dragging the hose between water buckets
in a calf greenhouse can create great fly breeding spots.
Especially in the calf greenhouses and coveralls, try to keep the
area in front of pens clean and dry. Sweep up spilled grain
Likely Fly Breeding Locations. Calf rearing areas, near water
sources and feed troughs / bunks, adult animal resting areas, maternity
and hospital pens, manure traps / conveyor systems. Outside areas
adjacent to barns prone to fly breeding include the water and feed
troughs in the animal loafing yard, base of stored big bales, and
edges of bunk or standing silos. Hard to clean corners and other
areas where organic matter can accumulate.
Evaluating Fly Populations: spot cards and direct observation.
Spot cards provide an objective means to monitor relative fly activity
over time. White index cards (3X5 inches) serve as a clean surface
to collect fly "specks" left by resting flies. Cards can be mounted
on posts, beams, walls, etc. Select areas 10 areas throughout the
barn where flies are seen resting. Do not put cards in windy areas
or within reach of curious "critters" and children. Draw a map to
indicate card location and save as part of your fly management record.
Date and number the cards and change them weekly. After 1 week remove
the cards and replace them with a fresh set. Count the number of
spots found on each index card. One hundred (100) spots per card
can be used as a guide to indicate a fly problem. Spot cards provide
an objective means to monitor relative fly activity over time. Each
farm can adjust this number to their individual tolerance threshold.
Check areas surrounding spot cards with high counts for fly breeding.
Stable fly (the biting flies) monitoring involves direct observation
to check the legs and bellies of 10 animals and count number of
resting flies. Check calf legs for patches of thin hair which can
indicate a reaction to stable fly feeding. Ten stable flies per
animal are considered a high number. Keep records of spot card and
stable fly counts for reference. More information can be found in
the Cornell IPM Factsheet:
Integrated Management of Flies in and around Dairy and Livestock
Soybean Rust Update
Weekly scouting is occurring on 19 sentinel plots located in
Cayuga, Chautauqua, Chemung, Chenango, Columbia, Genesee, Herkimer,
Jefferson, Montgomery, Oneida, Onondaga, Ontario, Seneca, Tompkins,
Wayne, and Wyoming Counties. Plant growth stages in NY state have
been reported to range from V2-R1. Low levels of Septoria brown
spot continues to be found in several of the sentinel plots. The
current risk of soybean rust infection in New York is extremely
low. Future risk in New York will depend on rust build-up in the
southern U.S., especially in commercial soybean fields. To date,
in 2006, soybean rust has been reported in five counties in Alabama,
12 in Florida, one in Texas, five in Georgia, and two in Louisiana.
Currently, there are no known reports of rust on commercially planted
soybean in 2006. Last updated ( July 12, 2006 )
For more see the
New York State Soybean Rust Information Center website.
Growing Degree Days in NYS
Ken Wise NYS IPM
Accumulated Growing Degree Days for March 1 to July 12
Base 50 F
*indicates missing data
Keith Waldron-NYS IPM
* Maintain crop records by field, including crop condition, inputs,
observations, issues, concerns, etc.
* Storage areas cleaned and ready to accept wheat harvest? Check
and disinfect inside, under and around grain bins.
* Mow around barn and farm facilities
* Clean and store weed sprayers. Flush tanks, booms, nozzles.
Established Alfalfa & Hay:
* Monitor for potato leafhopper- harvest early or spray on basis
* Monitor for diseases, particularly Verticillium wilt, record
information on disease species and location for future cropping
* Continue monitoring for potato leafhopper, weeds and diseases.
* Monitor fields for weeds and diseases: record information on
type and location for future cropping decisions.
* Plant birdsfoot trefoil by end of July.
* Adjust combine in preparation for winter grain harvest (late-July)
or spring grain Harvest (early to mid-August). Contract custom-operation
* Clean grain storage areas.
* Watch wheat grain moisture. Be ready to combine at 18 percent.
* Monitor corn rootworm adults at silking.
* Observe corn for crop growth and condition, weeds, foliar diseases
* Monitor for crop condition and growth stage, soybean aphids,
natural enemies, foliar diseases, soybean rust
* Continue manure management and release of biological control
agents (parasitic wasps) for house fly and stable fly control in
* 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,
adjust paddock rotation as needed.
* Provide annual maintenance to fertilizer and pesticide application
* Note any repairs to harvesting equipment as they are cleaned
* Ready combine for small grains or finalize arrangements for
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