View from the Field
Western NY and Finger Lakes
Spider mites have been reported in soybeans in Cayuga, Seneca
and Wayne counties. The fields where these pests are being seen
are in areas that seem to keep missing the spotty rain showers from
the last several weeks. Remember, hot, dry conditions tend to contribute
to spider mite infestations.
Soybean aphid numbers have taken off in areas of Ontario, Onondaga,
and Cayuga counties in the past week.
Phytophthora root rot has been reported in soybeans. Nancy Glazier,
NWNY team, found a patch in Monroe County, and Sarah Woodard, Cayuga
County CCE, found several affected plants. Sarah also reports that
downy mildew is around in soybeans.
Corn rootworm beetles are beginning to emerge around the area.
Most reports are of low numbers of potato leafhoppers, except in
The soybean sentinel plot field in Columbia County I monitor
was over threshold for soybean aphids last week (average of 600
The grower sprayed the field for soybean aphids on Saturday July
14. What seems odd to me is that there is still a fair number aphids
that seemed to have survived or re-infested the soybeans. These
soybean aphids were mostly on the lower leaves. There were plants
with as few as 10 aphids and some as high as 170 aphids/plant. The
average of aphids/plant was far below threshold at 55 aphids/plant.
Jeff Miller in Oneida County also reports that one of the fields
they monitor for soybean aphids was over threshold.
Potato leafhoppers are alive and well making a nice yellow effect
to alfalfa fields at the Cornell Research Farm at Valatie, NY. In
one field after counting 3 samples (10 swings of the 15” sweep net
= 1 sample) I counted 260 potato leafhoppers which is 3 times the
threshold limit for 10 to 12 inch alfalfa.
Know your corn rootworms
Corn is starting to tassel, and I observed male corn rootworm
adults for the first time in 2007 last week. Corn rootworm beetles
will be feeding on the pollen for the next few days, and then they
are most likely to be observed in the silks of developing ears.
Here’s a review of how to identify the adult rootworms:
Western corn rootworm (WCRW) adults are black and yellow beetles
that are approximately 1/4 inch long. The female is yellowish with
3 black stripes on its back, while the male is solid black with
a pale yellow area at the tip of its abdomen (see photo, and
stay tuned for a picture of a male WCRW). Northern corn rootworm
is slightly smaller than the western, and it is bright green in
color (see photo).
The northern corn rootworm (NCRW) used to be the predominant
species in New York State, but since the arrival of the western
in the 1980’s, the western has become the dominant species. When
scouting, 1 western corn rootworm equals 2 northern corn rootworm
adults. During pollination, developing ears can tolerate many rootworms
feeding on silks (10+ per ear) without suffering economic losses.
Do you know how to scout for Corn Rootworm?
You will need to scout all corn fields that will be kept in
corn next year from emergence of the tassel until pollination is
complete. Pollination occurs for three weeks and monitoring takes
about 20 minutes per field. You will need to monitor each field
once a week until you reach a threshold or until pollination is
over. Look for gravid, (i.e. mature, egg laying) corn rootworm females
beetles--the ones that, when you squeeze their bodies, release white
eggs from their posteriors.
Here’s how you scout:
Using the Sequential Sampling Card for Corn Rootworm
Are female beetles present? Mature and capable of egg laying?
Conduct the squeeze test (see above) to determine if they are
ready to lay eggs.
Approach a corn plant carefully because the beetles will
fly off if they disturbed too much.
Count the beetles on the entire plant.
For each corn plant monitored, record the total number of
beetles observed. See the sequential sampling chart below.
Since western corn rootworms are potentially more damaging than
their northern cousins, count each western (yellow striped)
beetle observed as “one” and each northern (green type) as “1/2”.
Check several plants at random (not next to each other!)
in several parts of the field.
Continue sampling at seven-day intervals until the ear silks
are brown, approximately 3 weeks after tassels are first visible,
pollination is complete or an above threshold number of beetles
Keep a running total (RT) of the number of corn rootworm
beetles you have counted on each plant. Each northern corn rootworm
has half the value of each western corn rootworm. The western
corn rootworm does twice the damage to corn than does the northern.
So if you count 3 westerns and 4 northern (2 western equivalent)
on a plant you would have a total of 5 beetles.
If the number of corn rootworm beetles observed is smaller
than the “N” (“Not at threshold”) number stop and scout 7 days
If the number of corn rootworm beetles observed is larger
than the “T” (“At threshold” or “Treat”) number then you need
to manage rootworms next year.
If the number of corn rootworm beetles observed fall between
“N” and “T”, continue sampling additional plants until you finally
go over or under.
In a very low or very high rootworm population a sampling
decision can be made in sampling as few as 3 to 8 plants. For
moderate populations more samples may be necessary to insure
N= No Treatment
T = Treatment
RT = Running Total
For more information on corn rootworm checkout our online publication:
Corn Rootworm Management in Field Corn
An Army of Worms Invading: True or Fall?
There has been recent discussion on armyworm in Eastern NYS and
Vermont. There are two common types of armyworm that can feed on
forage grasses, field corn and small grains. These are true and
True armyworm (Pseudaletia unipuncta) larvae appear
smooth , cylindrical, pale green to brownish when they are still
small. Mature larvae are smooth, hairless, and brown with a narrow,
mid-dorsal stripe and two orange stripes along each side.
True armyworm ranges in size from 1/8 inch to 1.5 inches long.
These are normally a spring pest and the adult moth travels on storms
from the south in May and lays eggs on grasses or small grains.
They feed on grasses, small grains and field corn as they develop
and are normally finished with their development by late June. There
can be exceptions since I have seen true armyworm larvae into mid
July feeding on field corn.
Fall Armyworm (Spodoptera frugiperda) larvae
are green, brown, or black, and about 1/8 inch to 1.5 inches long.
They 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.
Signs of Armyworms! Because armyworms feed at night, look
for chewed leaves, cut stems, lodged plants, pellet-like frass on
the ground, and larvae hidden under plant canopy and surface residue.
You will need to be aware that armyworms can move from field to
field every quickly. If larvae are less than ˝ inch long when you
monitor fields, and 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. Rarely does a
whole field need to be treated for armyworm. Larger armyworm larvae,
greater than 1/2 inch long, are much more difficult to control.
These large larvae are more tolerant of insecticides, reducing the
effectiveness and economic viability of this option.
Corn - More than 50% of plants show armyworm feeding, and live
larvae less than 1 - 1/4 inches long are numerous in field
Grasses - no specific guidelines available, need for treatment
based on the level of damage observed in relation to the expected
value of grass harvest.
Soybean aphids - Natural Enemies - Fungus Among Us
Soybean field surveys conducted in 2002-2003 by Cornell Entomologists
and the NYS IPM Program documented a rich diversity of natural enemies
attacking soybean aphids (SBA). These biological control agents
included various coccinellid species (lady bugs), lacewing and syrphid
fly larvae, minute pirate bugs, spiders, 60 species of ground beetles
and more. These surveys also found 2 parasitoids not previously
described as attacking soybean aphids (see last weeks issue).
In addition to various arthropod species, Cornell Entomologist Ann
Hajek and colleagues identified at least 7 species of entomopathogenic
fungi attacking soybean aphids in central NY. These fungi include:
Pandora neoaphidis, Neozygites fresenii, Lecanicillium lecanii,
Conidiobolus thromboides, and Entomophthora chromaphidis,
Zoophthora occidentalis and another undescribed species of Pandora.
None of these pathogens had previously been reported from soybean
aphids in the literature.
While many soybean fields have remained below threshold for SBA
in NY this season, above threshold soybean aphid numbers have been
reported in recent weeks. Relatively low populations of natural
enemies have been observed in some of these fields and many are
from areas that have experienced dry weather conditions. Recent
rains are welcome and may create the conditions favorable to stimulate
fungal diseases that help curb soybean aphid populations.
Fungal pathogens with the potential to cause substantial infection
in soybean aphids are clearly present in New York State. Can insect
diseases help moderate SBA populations? Given favorable weather
conditions and sufficient inoculum, our experience while limited,
has been favorable. For example, in 2003 SBA collections in heavily
infested soybean fields yielded 3% to over 75% of the aphids infected
with a fungal disease. One late planted field tracked closely yielded
an 84% infection by P. neoaphidis on August 8th. Although
the plants were sensitive to damage (early pod fill stages), the
grower decided not to spray with insecticide. Soon after, aphid
populations were observed to decline precipitously on their own,
as might have been predicted by the high rates of infection in samples
Take home message?
Watch fields closely. Continue to monitor fields for presence of
soybean aphids. Should monitoring detect a population at the 250
SBA's / plant threshold evaluate the crop for yellowing, stunting,
leaf curling and other signs of stress and note the presence of
natural enemies. Resample the field within the week to determine
if SBA populations have continued to increase.
Diseased aphids? What to look for...
Search for soybean aphids on the underside of leaves, stems and
petioles. Healthy aphids have a greenish-yellow color. Diseased
aphids appear "fuzzy" due to sporulation of the fungus and may be
pinkish, white, tan, or brown in color. The photo shows a healthy
soybean aphid compared to one infected with Pandora neoaphidis.
Also in the photo is a smaller white cast aphid skin.
(Photo courtesy of James Liebheer, Cornell Entomology).
Soybean Aphid Update
Soybean aphid update - July 20, 2007.
Sentinel site soybean fields reporting this week range from
the V2 - R2 growth stage, with most fields in the V5-R1 range. Soybeans
generally 12-16 inches, a few R stage fields at 20-24 inches.
Frequent field monitoring provides useful information for making
management decisions. Sentinel site reports this week from Monroe,
Ontario, Oneida, Seneca, and Wyoming counties indicate soybean aphid
populations all well below the 250 SBA / plant threshold. Onondaga
county reports V7 soybeans at 250 - >500 SBA / plant. Cayuga county
reported data for six fields, all in R-stages. All fields are at
or have gone over threshold. Four fields have been sprayed. Columbia
and Cortland county sentinel fields were treated last week for above
threshold SBA populations. The Wayne county sentinel site was treated
for a spider mite infestation. Natural enemy populations vary across
fields being monitored, numbers generally appear to be increasing
since last week. It should be noted that field by field monitoring
on individual farms has detected numerous situations where some
fields have high SBA populations while others are much lower.
Recent rains are expected to provide welcome relief to areas facing
dry conditions. Aphid populations can also be disrupted by heavy
rainfall events by washing them from leaves and exposing them to
predators. Rain may also help to create conditions more favorable
to entomopathogenic disease epidemics with potential to moderate
SBA populations. Surveys in the next weeks will provide more insights.
Growers are advised to continue monitoring fields for SBA's, crop
condition and growth stage. If fields reach the 250 SBA / plant
threshold, resample fields within a week to re-evaluate the
population level before taking action. Watch for presence of winged
(alate) aphid types on more heavily infested plants. An abundance
of winged aphids often indicates the aphid population is preparing
to emigrate. Notes could also be used to mention if any predators
or parasitized aphids (mummies) are present or other general relevant
observations. It is recommended that notes of presence and/or infestation
levels of other economically important pests of soybean such as
foliar, stem and root rot diseases, white mold and Bean leaf beetle
For assistance on soybean growth stages and soybean aphid decisions
"Reproductive Soybean Development Stages and Soybean Aphid Thresholds".
Thanks to: B. Aldrich, J. Lawrence, J. Degni, J. Dennis, M. Dennis,
K. Ganoe, N. Glazier, J. Miller, M. Stanyard, B. Tillapaugh and
K. Wise for sharing their Soybean aphid observations this week.
For more on the current national Soybean aphid perspective see:
Soybean Rust Update
Plant Pathology, Cornell University
Weekly scouting is being done in twenty New York State sentinel
plots located in the following counties: Cayuga, Chautauqua, Chemung,
Chenango, Columbia, Cortland, Jefferson, Monroe, Oneida, Onondaga,
Ontario, Oswego, Otsego, St. Lawrence, Seneca, Steuben, Suffolk,
Wayne, and Wyoming. Plant stages in these plots reported to date
range from V-2 to R-1. Low levels of septoria brown spot and downy
mildew have been reported in some of these plots.
Soybean rust has been recently reported in the last week in several
states in the Southeastern U.S. Mississippi reported their first
find of soybean rust this year on kudzu in Wilkinson County. Texas
reported soybean rust on soybean in a sentinel plot as well as a
surrounding commercial field in Victoria County. Florida reported
its first find on soybean this year in a sentinel plot in Marion
County. To date in 2007, soybean rust has been detected in ten counties
in Florida, five counties in Georgia and Alabama, five Parishes
in Louisiana, four counties in Texas and one county in Mississippi.
Weather in the Southeast remains favorable for rust development.
(Updated July 16, 2007 )
* Maintain crop production activity records by field, including
harvest date, pesticides used, nutrient inputs including manure,
* Enjoy your family. Take them swimming!
Established Alfalfa & Hay:
* Begin second harvest of alfalfa about 40 days after first cutting
if weather conditions are favorable
* Record hay yields by field and quality by storage facility; take
samples for forage analysis
* Top dress hay fields if necessary.
* Monitoring alfalfa regrowth for potato leafhopper
* Monitor for diseases, particularly Verticillium wilt, record information
on type and location for future cropping decisions.
* 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 summer seedings. Plant birdsfoot trefoil by end of July.
* Watch wheat grain moisture. Be ready to combine at 18 percent.
* 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.
* Monitor corn rootworm adults at silking.
* Observe corn for weeds and fertility
* Monitor for soybean aphids, and other insects, including natural
enemies such as lady bird beetles.
* Check droughty fields for presence of spider mites
* Monitor for soybean aphids, and other insects, including natural
enemies such as lady bird beetles.
* Check droughty fields for presence of spider mites
* Continue manure management and release of biological control agents
(parasitic wasps) for house fly and stable fly control.
* 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.
* Note any repairs to harvesting equipment as they are cleaned and
- Repair forage harvest equipment as needed
* Ready combine for small grains or finalize arrangements for custom
Julie Dennis: IPM Area Educator, Livestock and Field Crops, Western
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