July 8, 2005 Volume 4 Number 12
1. View from the Field
2. Soybeans at Risk From Spider Mites
3. Start Thinking Corn Rootworm-What fields are
4. Do you have Wirestem Muhly?
5. European Corn Borer Opens the Door for Anthracnose
6. Clipboard Checklist
7. Growing Degree Days in NYS
8. Contact Information
Keith Waldron, NYS IPM
NY Weed Science Field Day, Robert
B. Musgrave Research Farm, Aurora, NY (Poplar Ridge Road, connects
90 and 34B) (July 13 Wednesday)
NY Weed Science Field Day, H. C. Thompson Research Farm,
Freeville, NY (10 miles Northeast of Ithaca, Fall Creek Road,
Rt. 366 extension) (July 14 Thursday)
Aurora Field Day, Robert B. Musgrave Research Farm, Aurora,
NY (July 15 Friday)
Potato leafhoppers on alfalfa at the SUNY Cobleskill farm
remain at low infestation levels. Both established stands and
new seedings had lower levels of potato leafhopper. One reason
that potato leafhopper are remaining at lower levels is the
heavy rains help control the insect.
While scouting field corn I saw several plants with European
corn borer damage. There were very few weeds in both the no-till
and conventional tilled corn fields.
Soybean aphid populations in most of our production areas
appear to be stable and still well below the 250+ SBAs per
plant action threshold. Opportunities for SBA Treat / No Treat
insecticide comparisons are being sought.
at risk from Spider Mites
Julie Stavisky, NYS IPM
While some areas of NY have received
substantial rain over the past week, other places remain very
dry. Compound the dry weather with the recent high temperatures,
and we have the ideal conditions for spider mite invasions into
Two-spotted spider mites are tiny, oval, 8-legged,
pale-bodied arachnids. The feeding of spider mites causes a
stippling of leaves. Severe feeding by many mites causes a bronzing
of the leaf. The injury from spider mite feeding can resemble
a foliar fungal disease infection. Another identifying factor
of spider mites is the silk-like webbing they produce. The webbing
can be seen on leaflets and petioles in a heavily infested field.
The mites are able to use the silk to transport by wind to uninfested
areas of a field. When scouting, to help to confirm the presence
of spider mites, hold a white piece of paper under a plant.
Tap on the plant, and some of the mites should fall to the paper.
They appear as yellow or yellow brown moving specs.
Spider mite injury to soybean leaf
Spider mite populations can increase extremely rapidly -
they can develop from egg to adult in 5 days with high temperatures.
Cool, damp weather often leads to steep declines in spider mite
populations by encouraging fungal pathogens to take control.
Spider mites are regular residents of weedy areas at field
edges. During dry weather, if these weed hosts become stressed,
spider mites may begin to move into the nearby crop. Thus, an
infestation usually begins at field edges and radiates into
the field. While a spot-treatment with an insecticide may be
helpful to combat the start of a severe infestation, it is critical
to scout the whole field. Low numbers of spider mites can be
present before the injury can be seen from a distance. When
chemical control is chosen for spider mite management, it is
critical to bear in mind the risks of "flare-ups" from use of
CORN ROOTWORM: What Fields are at risk?
Ken Wise, NYS
Corn rootworm populations build
in a cornfield from year to year. Fields that are not rotated
and remain in corn for several years are most at risk from corn
rootworm damage. A two to three year rotation reduces the risk
that a corn field will reach an action threshold for this pest.
This spurs the question, Do you scout a 1st year cornfield
after sod for corn rootworm? Yes, because any pollinating cornfield
can attract corn rootworm. Even worse, late pollinating corn
can attract many hungry corn rootworm beetles from fields where
they did not get enough pollen. After the beetles eat their
fill on late season pollen they will lay eggs in the soil. So
yes, you have to scout all cornfields for corn rootworm that
are going to be planted to corn next year. You do not need to
scout fields that will be rotated out of corn next year. For
more information on corn rootworm checkout our online publication:
Corn Rootworm Management Guide
972 pdf file
Do you have
Ken Wise, NYS IPM
Wirestem Muhly is a warm season
perennial grass. Itis native to the North America and has become
problematic in field corn in certain areas of NYS. The grass
spreads by short and scaly rhizomes. The stems are 2 to 3 feet
in length, smooth below joints, very tough, leafy, branch freely,
and often root at the lower nodes. Leaves are flat, rough, pale
green, scattered along the stem, and dense near the tip, giving
the plant a brushy appearance. The panicle barely protrudes
from the leaf sheath. This weed normally starts as scattered
clumps in a field and will spread over time. The problem with
wirestem muhly is that only glyphosate products can control
this weed. This limits your choices to using glyphosate resistant
corn plus glyphosate or rotate the field to a different crop.
One thing you need to think about is not transferring the weed
around your farm. If you have wirestem muhly make sure to clean
tillage equipment before working a field that is free from the
weed. The rhizomes can be transferred on tillage equipment from
field to field. For pictures of the weed view this website:
Corn Borer Opens the Door for Anthracnose Stalk Rot
Wise, NYS IPM
While scouting, I observed signs
of European corn borer (ECB) in field corn. There were broken
leaf midribs, frass in the whorls, and holes in the stalks.
European corn borer damage, can on occasion cause localized
problems for field corn producers. However, while it's damage
may be conspicuous, it more typically does not cause significant
economic losses in NYS. If a field has had a history of ECB
problems producers might consider crop rotation or the use of
an ECB resistant (Bt) hybrid. In addition to direct feeding
damage the holes bored by ECB larvae can provide a means for
the anthracnose fungus to enter the plant. Conditions that favor
anthracnose stalk rot are continuous corn, surface corn residue
(minimum & no tillage) and wet, humid, warm weather. Anthracnose
stalk rot symptoms may appear after tasselling. Look for vertical,
tan to reddish brown, water-soaked lesions (streaks) in the
rind. Lesions become large, dark brown to shiny black. The best
management practices to minimize or avoid anthracnose require
action before or at the time of planting, i.e. the use of diseases
resistant hybrids and hybrids with a good standability rating.
Crop rotation with non-grass crops and plow under infected residue
are also recommended. Fields with high amounts of anthracnose
leaf blight should be checked for indications of anthracnose
stalk rot. If stalk rot is found you may wish to target that
field for early harvest to avoid losses associated with premature
lodging. For more information on corn diseases checkout our
online publication: Diseases of Corn Management Guide
234k pdf file
Soybean Rust Update
Septoria brown spot and bacterial
blight have been observed in NY, but fortunately still no reports
From the NYS soybean rust website: 2005 Asian Soybean Rust
Soybean rust on soybeans has been reported in Florida and
some adjacent counties in Alabama and Georgia. Recent Alabama
and Florida finds were in sentinel soybean plots, the Georgia
find was on volunteer soybeans. Scouting and spore trapping
continues throughout the soybean production areas of the U.S.
Scouting of sentinel plots in NYS continues this week and to
date no soybean rust has been found. Septoria brown spot is
the most prevalent foliar disease in all 10 of the research
protocol sentinel plots in NYS over the past two weeks. Bacterial
blight has also been observed. Growth stages in NYS sentinel
plots range from V3 to R1 stages and several will come into
flowering soon. Scientists are monitoring two current tropical
storms for their potential to move soybean rust spores to wider
areas of the U.S. (Last updated 7/6/05). For more see
New York State Soybean Rust Information Center.
Soybean Rust in US 7.6..05
USDA Public Soybean Rust Website
National Map Commentary (updated: 07/01/05)
Intensive scouting is continuing throughout eastern North
America from the Gulf coast to southern Ontario wherever soybean
is grown with no new finds. Although many areas in the southeast
U.S. has been wet this past month, which encourages disease
spread, air temperatures are now climbing to levels that are
less favorable for spore production. However, if the winds and
rain associated with tropical storm Arlene were involved in
transporting soybean rust spores from known U.S. sources, and
potentially other unknown sources in the U.S. and the Caribbean
basin, new soybean rust infections could soon be observed.
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, particularly Verticillium wilt, record
information on type and location for future cropping decisions.
Prepare for summer seedings of alfalfa. Test soils. Lime
Prepare for grain harvest: combine ready?, check and disinfect
inside, under and around grain bins.
Watch wheat grain moisture. Be ready to combine at 18 percent.
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
Initiate integration of biological control agents into
house fly and stable fly management program.
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.
Growing Degree Days in NYS
March 1 - July 5,
Base 50 F
1053.5* * Missing data
Julie Stavisky: IPM Area Educator,
Livestock and Field Crops, Western NY
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