Weekly Field Crops Pest Report 2008
View from the Field
Ken Wise & Keith Waldron
No reports this week of major field crop pest activity across the state.
Most observations reported this week include mention the impact frequent rain showers are having on field activities such as wheat and forage harvests, crop growth and development and apparent nutrient uptake. Moisture can help encourage epizootics of fungal diseases of insects that can help curb populations of such pests as soybean aphid. Moist conditions can also favor various field crop diseases. While moisture is needed for healthy crop growth, moderation and timing is appreciated!
Potato leafhopper (alfalfa) and soybean aphid (soybeans) counts appear to be low this week. Both insects, however, can be transported with weather fronts and may become more noticeable in the weeks to come. Only by scouting will we know for sure. Stable flies, a pest of dairy animals, other livestock and humans can also be transported on weather fronts. As noted in last weeks pest report, numbers of this pest have noticeably increased over the last several weeks.
There have been some reports of Japanese beetle defoliation injury in soybean fields across the state. The good news is that soybeans can withstand a lot of feeding before any yield losses can occur. The soybean defoliation threshold is 35 percent of leaf area eaten or missing from V1 to just before bloom. During blooming through pod-filling stages, the threshold is 20 percent defoliation.
Corn tasselling and silking is more obvious in many areas across the state this week. Make sure to monitor any corn field that will remain field corn next year for corn rootworm beetle assessments. For no-till corn or fields with high previous crop residue, watch for early signs of foliar diseases.
Temperatures averaged slightly above normal last week across
NY. The Southern Tier, Great Lakes and
Last week approximately 150 base 50 GDD accumulated across central
The pesky upper air low that has given us our fair share of rainfall
this week, will start to depart today and finally exit the region
on Friday, The next front approaches the state on Saturday and will
bring NY another showery weekend. By Monday the region should
see another 1 inch plus rain event with locations in the extreme
eastern parts of the state, including NY City and Long Island and
Beyond mid-week, a trough is expected to persist in the east continuing the pattern of frequent showers and generally normal temperatures.
Corn Rootworm Scouting TIP!
Remember, when taking beetle counts you are monitoring to assess
the potential that
When is the best time to control corn rootworm if a field exceeds the action threshold?
The following year!
If there is a field over the action threshold what are the options for control next season?
The best option to control corn rootworm is crop rotation. Corn after corn is prime habitat for corn rootworm and will increase infestations from year to year.
Crop rotation is not always possible so. The second management option is the use of a soil-applied insecticide at planting. To select an insecticide registered for corn rootworm, please consult the Cornell Guide for Integrated Field Crop Management.
<http://nysipm.cornell.edu/publications/crw_bro/default.asp>How to Monitor for Corn Rootworm
White Mold in Soybeans
Highly productive, wet and dense stands of soybeans favor white mold development. The fungus survives from year to year in the soil as hard black pellets called sclerotia. Sclerotia of white mold must be present to cause the disease, and a small number of sclerotia on the soil surface can lead to significant outbreaks if wet, cool conditions are present while plants are flowering. Under favorable conditions, sclerotia germinate and form small mushroom-like structures (apothecia). The apothecia produce ascospores which can be spread by wind and splashing rain. Ascopsores require a nutrient source to grow, and soybean flowers serve as ideal locations. The fungus colonizes dead flowers and the characteristic thick white, cotton-like moldy covering on stems and pods develops (see photo below). Close inspection should reveal the black (rat feces-like) sclerotia mixed in with the white mold on stems. Infected plants can show wilt symptoms and stems will have a soft rot. Infection leads to premature death of plants. If white mold infection occurs late in the season, yield loss will not be as severe. Temperatures over 90 degrees will typically stop disease development. During harvest, the sclerotia on stems and pods may end up in the soil or residue, or may stay with harvested seed. Fields where white mold has occurred in the recent past are where it will most likely occur, so these are the fields to scout the most closely for disease development.
The following photo shows the white mold infection on a plant that is starting to wilt.
Photo taken by Mike Stanyard
A key to white mold management is to find strategies to prevent the build-up of the pathogen in a field. In addition to soybean, common bean and sunflowers can serve as favorable hosts for this disease. . Rotation to nonhost crops such as corn, wheat or other grass for at least 1 year (ideally 2 or more years) is recommended. Additionally, weed management practices that reduce weeds that serve as alternate host for white mold (for example lambs quarters and pigweed) will help to decrease build-up of the pathogen. It is also essential to avoid the planting of contaminated or infected seed, and to avoid the movement of infected soil with equipment. A strategy for preventing movement of infected soil is to harvest fields infected with white mold last. Varieties of soybeans that are tolerant or moderately resistant to white mold should be selected. Yield protection by spraying fungicides has not been documented in New York.
Pollen Islands will Attract CRW
Remember those corn fields that had troubles with uneven emergence,
ponding, compaction, fertilizer, herbicide, or other planting time
issues? Drive by many of these fields this week and their up and
down plant height patterns look more like a side view of a crazy
roller coaster ride than the ideal production field. And now watch
the pattern of tassel emergence. Whatever the reason for the
uneven stand its effect on corn rootworm (
Since these areas can be at higher risk for egg laying make
a note of their location(s). Record any scouting information. Should
egg laying be high enough in those islands, it is a good bet that
they would be at higher risk for lodging from
NOTE: The sequential sampling method for sampling
If sampling for
Partial Alfalfa Field Harvest Increases PLH risks
Are PLH in your alfalfa fields? If so, avoid partial field harvests to best manage PLH populations. Clean harvest of whole alfalfa fields is optimal, however our recent stretch of rainy weather has surely messed up more than one harvest schedule sometimes stopping a hay harvest in mid-stride. These partially harvested fields can set the stage for future PLH problems. In situations where edges or portions of alfalfa fields have been harvested but other areas of the field are left intact watch closely for PLH populations and potential injury.
Adult PLH in the standing portion of the field can easily relocate to the shorter portion of the field and attack the vulnerable regrowth. The shorter alfalfa has a lower threshold for PLH than taller alfalfa so is at much higher risk for injury.
Harvesting remaining portions of the field as soon as is practical is recommended to minimize PLH population buildup and their easy movement to adjacent portions of the field.
Soybean Rust Update
Sentinel plots in
Since the beginning of 2008, soybean rust has been reported on
kudzu in one county in Alabama; one county in Georgia, thirteen
counties in Florida (two of these counties had reports on coral
bean and snap bean and one had a report on soybean); three counties
in Louisiana; one county in Mississippi, and three counties in Texas.
Reported infected kudzu sites in many counties have been destroyed.
Rust was also reported in three states (5 municipalities) in
Soybean aphid update
No soybean aphid issues have been reported in NY so far this season.
Crop Growth Stage - V-1 to R-2
Variations in planting dates have soybean growth stages ranging from early vegetative (V2-V4 to R1, some fields in western NY just beginning to enter R2 stage). Soybean heights also vary from 12 inches to nearly 30 inches tall.
Observation and Outlook - Insect
Soybean aphid (SBA) populations continue to remain low across areas reporting in NY. SBA's are present in many (but not all) locations reporting from across the state, generally averaging 0 to less than 5 SBA's per plant. Occasional individual plants may have higher numbers. All fields reporting well below threshold. Natural enemy populations, such as lady bird beetles, are present and increasing in many areas.
Field monitoring has been hampered by frequent storms. It is not clear whether the storms have been helping to physically knock down SBA numbers from populations that may have been in fields or if the storms will be a source of new SBA from other regions. It is also possible, though not yet substantiated by direct observation, that the moist conditions brought by storms may be enhancing the biological control of SBA by entomopathogenic fungi. As mentioned earlier, only by scouting will we know for sure.
Scouting and Management - Growers are encouraged to monitor for presence of soybean aphids, other insects and diseases. Fields entering the blooming stages should be monitored closely for SBAs, foliar diseases and white mold.
For more on the current national Soybean aphid perspective see: www.sbrusa.net.
* Emergency contact information ("911", local hospital, Chem. Spill emergency contact, other?) posted in central posting area
* Maintain crop records by field, including variety, planting date, pesticides used, nutrient inputs including manure, yields, etc.
* Watch for weed escapes, any patches of herbicide resistant weeds?
* Check crop growth stage and condition
* Check for European corn borer, armyworm, foliar diseases, vertebrate injury (birds / deer), weed escapes, herbicide injury, nutritional deficiencies, etc.
* Tasselling / Pollinating corn check corn rootworm populations
* Monitor weed populations noting presence of "who", "how many" and "where"
* Check herbicide resistant corn fields for herbicide resistant soybean
* Adjust post emergence weed control actions
* Evaluate standing crop for timing grain and straw harvest, evidence of sprouting (wheat)
* Storage areas cleaned and ready to accept next harvest?
Alfalfa & Hay:
* Monitor alfalfa seedings for weeds, for potato leafhopper & diseases.
* Check established alfalfa stands for potato leafhopper, weed and disease problems.
* Storage areas cleaned and ready to accept next harvest?
* Check crop growth stage and condition
* Evaluate stand for soybean aphid, spider mites, deer, weed assessment, foliar disease incidence
* Check herbicide resistant soybean fields for herbicide resistant corn
Dairy Cattle: Livestock Barn Fly Management:
* Monitor animals and facilities for house fly and stable fly populations
* Check facilities for favorable fly breeding conditions: (organic matter + moisture): leaks in watering systems, roof gutters for leaks and potential overspill, drainage,
* Sanitation, sanitation, sanitation - clean animal resting areas, feed troughs, minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal loafing yard * Continue fly monitoring: install "3X5" index card fly speck monitoring cards through out barn
* Order fly management materials: fly tapes, insecticide baits, natural enemies (parasitoids)
* Continue release of purchased natural enemies (fly attacking parasitoids)
Dairy Cattle: Pasture Fly Management:
* Monitor animals for presence of face flies, horn flies and stable flies.
* Check feed bunk / water source locations for signs of stable fly breeding (moist undisturbed organic matter ć spilled feed, round bales, etc.) , minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal loafing yard
* Check paddocks for forage quality / quantity, rotate as appropriate
* Check paddocks for vegetation poisonous to livestock
* Consider use of fly traps to help reduce deer, horse and stable fly populations
* Pre-clean in and around grain bins before adding newly harvested wheat.
* Keep areas around storage bins and silos clean and mowed
* Note any repairs needed for recently used equipment: tractors, tillage implements, harvesting equipment, etc. as they are cleaned and serviced.
* Calibrate manure spreaders - maintain records on amount spread per field
Keith Waldron: NYS Livestock and Field Crops IPM Coordinator
Ken Wise: Eastern NYS IPM Area Educator: Field Crops and Livestock