Volume 15 Number 13
View from the Field
Potato leafhopper (Empoasca fabae) is increasing rapidly in population in alfalfa. The hot dry weather is ideal for potato leafhoppers. Several growers have sprayed an insecticide in fields over threshold for potato leafhopper. If you have short alfalfa that is turning yellow it is best to clip it off and monitor for the pest. The quality of the forage will not be very good. Spray when you reach an economic threshold on the regrowth. For more information view the following short video on potato leafhopper in alfalfa. IPM For Potato Leafhopper in Alfalfa
Northern Stem Canker has been found in a field of soybeans in Dutchess County. It was an early detection. Here is an article By Dr. Jaime Cummings and Dr. Gary Bergstrom (Cornell Plant Pathologists) on this disease: Northern Stem Canker: A New Challenge for New York Soybean Producers
Mike Stanyard (CCE Dairy and Field Crops Team Northwest NY) report corn rootworm beetles and Japanese beetles at high number feeding on silks of field corn. In some cases there were 12 corn rootworm beetles per plant across the field. If the silks are clipped to too short the kernels cannot be pollenated. A few fields were sprayed for the beetles because the silks were clipped to less than a ½ inch. If the silks are starting to turn brown the corn has been pollenated and the beetles cannot reduce yield at this point.
Threshold for Corn Rootworm Beetles on Silks in NY
If 10 or more adults are found per plant at silking, less than 50 percent of corn silks are brown, and silks <0.5 inch long, treatments to control adults may be warranted, and pollination has not yet occurred, apply an insecticide. Pollination generally occurs within three to four days after silk emergence. The silks quickly dry up after pollination.
Threshold for Japanese Beetles on Corn Silks.
The following is the threshold for Japanese Beetles feeding on corn silks. (Sources: Japanese Beetle Scouting and Thresholds for Corn-University of Wisconsin)
Consider a foliar insecticide treatment during tasseling and silking if there are
- 3 or more beetles per ear
- Silks have been clipped to ½-inch
- Pollination is less than 50 percent complete
Extension educators are starting to see northern and western corn rootworm beetles in field corn. Do you know the difference between these two beetles? See article below on identification and monitoring for corn rootworm.
Dr. Elson Shields (Cornell University Professor-Field Crops Entomology) reports that an experiment he is conducting on biological control with soil applied entomopathogenic nematodes to control corn rootworm is working well. Root feeding on corn by corn rootworm larvae was dramatically reduced in the treated areas. The nematodes attack and infest the corn rootworm larvae in the soil and kill them.
There are reports of very high populations of pea aphids in alfalfa. We generally do not worry much about pea aphids but in combination with potato leafhopper and drought may be adding more stress the alfalfa.
Several Extension educators are starting to see spider mite damage in soybeans. Spider mites LOVE hot-dry-drought like conditions. Keep a close eye on this pest.
Weather Outlook – July 28, 2016
NOAA Northeast Regional Climate Center, Cornell University
Last week temperatures ranged from 2 to 6 degrees above normal for most of the state. Precipitation ranged from a tenth to 2 inches. Base 50 growing degree-days ranged from 120 to 180.
Some unsettled weather brings hope for rain, temperatures heating up again next week…
Today will be hot & humid, a cold front will bring isolated showers and thunderstorms with temperatures in the upper 70’s and 80’s. Overnight lows will be in the 60’s to low 70’s.
Friday showers and non-severe thunderstorms will bring locally heavy rain to eastern portions of the state with highs in the mid 70’s to mid 80’s. Lows will be in the mid 50’s to 60’s.
Saturday will be dry with temperatures will be in the mid 70’s and 80’s. Overnight temperatures will be in the mid 50’s to mid 60’s with a chance for showers and thunderstorms.
Sunday there will be a continued chance of showers and thunderstorms with highs in the mid 70’s to mid 80’s. Overnight temperatures will be in the upper 50’s to mid 60’s.
Monday the highs will be in the upper 70’s to mid 80’s. Lows will be in the mid 50’s to mid 60’s.
Tuesday temperatures will be 80’s to near 90. Lows will be in the upper 50’s to mid 60’s.
Wednesday temperatures will be in the mid 80’s to low 90’s. Lows will be in the 60’s.
The five-day precipitation amounts will range from 1/10 ” to 2.5”, with the highest amounts in southeast NY .
The 8-14 day outlook (August 4-10) shows equal chances for above or below normal temperatures for most of the state, an increased chance (33-40%) for above normal temperatures for southeast and southwest NY. There is an increased chance (40-50%) for below normal precipitation for the entire state.
The Drought Monitor: There has been a slight expansion of severe drought in central NY and moderate drought in the Hudson Valley. U.S. Department of Agriculture (USDA) rating topsoil moisture at least half short to very short on July 24 New York (54%). Drought was also apparent in low streamflows, particularly across western New York. Buffalo, New York, received 1.80 inches of rain during the first 26 days of July, 68% of normal, following its driest April-June period since 1941. Buffalo’s precipitation totaled just 4.42 inches (44% of normal) in April-June 2016.
Maps of 8-14 day outlooks:
National Weather Service watch/warnings map:
US Drought Monitor:
CLIMOD2 (NRCC data interface):
Know your corn 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.
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.
Northern Corn Rootworm
Scouting for Corn Rootworm
Ken Wise-NYS IPM
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 female beetles–the ones that, when you squeeze their bodies, release white eggs from their posteriors.
Here’s how you scout:
- 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.
- Grasp the silk with one hand.
- Count the beetles on the entire plant.
- Start counting at the top working down.
- Gently pull leaves away from the stalk so you count any beetles that may be hiding in the whorls.
- 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 are found.
Using the Sequential Sampling Card for Corn Rootworm
- 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 later.
- 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 accuracy.
Western Bean Cutworm Update 7.29.16
Western bean cutworm trap catches took this past week with 4X as many moths caught this week than last. Higher moth captures more often found in western and northern county than southern or eastern locations. See summary table below.
Monitoring fields for WBC egg masses:
As trap accumulations approach 100 moths per traps risk of WBC infestation increases and field monitoring for egg masses and young larvae is recommended. Pre-tassel corn is the preferred host for egg laying WBC moths. Egg masses will be laid on the upper surface of leaves close to emerging tassels including leaves in the whorl. Check 10 – 20 consecutive plants in at least 5 random locations in the field. Threshold for field corn is 5% of plants with WBC egg masses. Egg masses are typically laid on upright leaves or those just beginning to lay over. I usually check top 4 leaves.
If leaves are oriented towards the sun you can see the egg masses better on the top side of leaf or if looking at the bottom surface of leaves look for a shadow of an egg mass on the upper surface of the leaf. WBC eggs take ~5 – 7 days to hatch turning purple 1 – 2 days prior to hatch. Newly hatched larvae initially feed on their egg case and then make their way to silks or ears. If suitable food sources are not found the larvae will starve.
Several video’s are available on-line on how to monitor for WBC egg masses in corn.
For dry beans it is suggested that fields be monitored for signs of pod damage when nearby WBC trap catches approach 100 WBC’s per trap or local corn fields reach threshold. Further details regarding monitoring for WBC can be found in the Weekly Pest Report (http://blogs.cornell.edu/ipmwpr/2014/07/25/nys-ipm-weekly-field-crops-pest-report-july-25-2104/). Pictures of WBC larvae and moths including look-a-like moths and larvae can be found at: http://www.msuent.com/assets/pdf/07WBCID.pdf
|St. Lawrence||South Colton||1||2||15|
|St. Lawrence||North Lawrence||0||6||132|
|St. Lawrence||Chase Mills||4||9|
|Steuben||North Cohcoton Hill||0||0||0||4||4||6|
|Avg WBC / Trap||0.0||0.0||0.3||1.5||11.6||54.5|
|> 0 WBC||0||1||14||27||53||60|
|% Traps Catching||0.0%||3.6%||26.9%||44.3%||82.8%||93.8%|
Keith Waldron, NYS IPM
*Walk fields to check general field condition, weed, vertebrate and other issues
*Watch for crop maturity, stand assessments, weed escapes, nutrient deficiencies, lodging issues
*Evaluate established legume stands for approximate days until harvest
*Monitor potato leafhopper, foliar, systemic and crown rot diseases.
*Monitor new seedings for potato leafhopper, pythium blight, phytopthora root rot.
*Monitor grain fields for growth stage, disease and lodging issues, grain maturity, harvest timing
*Record diseases present, location and types of weed escapes
*Monitor for mid-season corn pests including European corn borer, corn rootworm, western bean cutworm, slugs, foliar diseases such as northern corn leaf blight and gray leaf spot, weed issues, nutrient deficiencies, vertebrate damage.
*Monitor for soybean aphid, defoliators, foliar diseases, white mold, weed issues, vertebrate damage
*Check water sources, mend fences as needed.
*Check crop growth, clip pastures between grazing as needed
*Monitor for invasive species, plants harmful to livestock
* Check stored grain bins for temperature, moisture and signs of mold and insects. Aerate, core, transfer grain or treat as necessary
* Clean and disinfect empty storage bins in preparation for grain harvest
*Check forage allocation and anticipate feed program adjustments as forages from previous year are used up
*Mow around storage bins and facility to minimize pest hiding places
Dairy Cattle Barn Fly Management:
*Monitor animals and barn area for house fly, stable fly and other pest management needs including presence of rodents and birds.
*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 throughout barn
*Use, replenish, replace fly management materials: sticky fly tapes/ribbons, insecticide baits, natural enemies (parasitoids), fly population monitoring (3 x 5) spot cards
*Consider purchase and release of Muscidifurax raptor and/or M. raptorellus natural enemies of house and stable fly pupae.
Dairy Cattle on Pasture:
*Monitor animals for presence of face flies, horn flies and stable flies. Action guidelines: face flies (average 10 per animal face), horn flies (average 50 / dairy per animal side, 200 / beef cattle per animal side), stable flies average 10 per animal (all four legs)
*Check feed bunk / water source locations for signs of stable fly breeding (moist undisturbed organic matter – spilled feed, round bales, etc.), minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal exercise yard.
*Check pasture for forage quality / quantity, rotate as appropriate
*Check pasture for vegetation poisonous to livestock
*Consider use of pasture fly traps to help reduce deer, horse and stable fly populations