July 20, 2018

NYS IPM Weekly Field Crops Pest Report, July 20, 2018

View from the Field

Potato Leafhopper (Empoasca fabae)

Potato Leafhopper (PLH)  populations in alfalfa are sporadic across the state. Under drought conditions, PLH populations can increase rapidly. With rain coming next week this may or may not slow PLH on alfalfa.

Potato Leafhopper Adult

It is very important to check fields now before damage occurs. The PLH nymphs are currently in fields. Nymphs do more damage than the adults. New seedings are more sensitive to PLH damage than established stands, and when a field has the added stress of drought will make the damage worse.  If the weather stays hot and dry, PLH populations may explode. Make sure to get out and check your fields, NOW!

We have an IPM training video for PLH in Alfalfa (8 minutes long). The video helps you understand how to monitor and determine thresholds for PLH. It also outlines IPM strategies for control of potato leafhopper, including harvesting early, planting resistant cultivars and utilizing insecticides.  Check out the video here: IPM for Potato Leafhopper in Alfalfa

And, See articles below for more information on PLH.

 Common rust (Puccinia sorghi) on corn

Mike Hunter (CCE Northern NY) reports finding common rust on corn in Northern New York. This fungus is brought on storms from the southern US. The spores become airborne and are blown here on fronts that move north. Since we have had several storm fronts this year, we have received the inoculum and the disease is spreading. The disease proliferates at 60 – 70◦ F with wet weather. The best way to combat this disease is to select resistant hybrids.


Common rust on field corn

“The symptoms are small, round to elongate brown pustules form on both leaf surfaces and other above ground parts of the plant. As the pustules mature they become brown to black. If disease is severe, the leaves may yellow and die early.” Common rust generally does not require a fungicide application and is not economical in field corn.  Source: https://fieldcrops.cals.cornell.edu/corn/diseases-corn/common-rust

 Soybean aphids (Aphis glycines)

Soybean aphid populations are increasing across the state. There have been some reports of aphids approaching the 250 aphids/plant economic threshold between the R1 and R5 stage of soybean growth. See article below on how to scout for soybean aphid.


Two-spotted spider mites (Tetranychus urticae) on soybeans

Mike Stanyard reports spider mites are reaching levels that are causing damage to soybeans. Spider mites in soybean occur when there are drought conditions in the field. Two-spotted spider mites can commonly be found in soybeans, but they become problematic under severe drought conditions in the field. Two-Spotted Spider Mites are not insects. They are more closely related to spiders, and they are VERY tiny… less than 0.002 inches long. They look like a speck of dust on the plant to the naked eye. To really see them well you will need a 30+ hand lens or a dissecting scope. The anticipated rain in the forecast for much of the state should help reduce two-spotted spider mites in soybeans

True Armyworm (Pseudaletia unipuncta)

True armyworm has been found sporadically in cornfields across the state. Some growers decided to spray for them. Armyworm issues should end soon though as the corn gets taller and armyworms pupate and will no longer feed. In years with large populations, the 2nd generation could be an issue. I do not expect that this year.

Weather Outlook –July 19, 2018

Jessica Spaccio

NOAA Northeast Regional Climate Center, Cornell University

Last week temperatures were near-normal to 6 degrees above-normal. Precipitation has ranged from a trace to 4”. Base 50 growing degree-days ranged from 100-180. Moderate drought expanded in western NY, where the rain has missed; abnormally dry conditions expanded farther north.


Dry sunny weather to end the week, unsettled weather starting over the weekend.


Today will be dry and sunny with temperatures in the mid 70s to low 80s. Overnight lows will be in the upper 40s to low 60s.

Friday highs will be in the mid 70s to low 90s with sunny and slightly humid conditions. Overnight temperatures will be in the 60s with light scattered showers possible in western NY.

Saturday temperatures will be in the upper 70s to 80s with light scattered showers possible in western NY. Overnight temperatures will be in the 60s with scattered showers and thunderstorms beginning in some areas.

Sunday highs will be in the 70s to low 80s with widespread showers and scattered thunderstorms. The potential exists for flooding for some areas. Overnight temperatures will be in the 60s.

Monday temperatures will be in the mid 70s to 80s with scattered showers and thunderstorms. Overnight temperatures will be in the 60s.

Tuesday highs will be in the mid 70s to 80s with scattered showers and thunderstorms. Overnight temperatures will be in the 60s.

Wednesday possible scattered thunderstorms with in the 80s. Overnight temperatures will be in the 60s.

The seven-day precipitation amounts will range from one and a quarter inches in western areas up to 5 inches in southeast NY.

The 8-14 day outlook (July 26 – Aug 1) favors near-normal temperatures for most of the state, slightly favoring below-normal temperatures for extreme western NY and slightly favoring above-normal temperatures in part of eastern NY. The precipitation outlook favors above-normal precipitation for all of the state.

Maps of 8-14 day outlooks:


National Weather Service watch/warnings map:


US Drought Monitor


Drought Impact Reporter:


CLIMOD2 (NRCC data interface):



Time to Scout for Potato Leafhopper in Alfalfa!

Ken Wise


Scouting alfalfa fields is the key to early detection of potato leafhopper infestations. Use a 15-inch diameter sweep net to determine the potential risk a potato leafhopper infestation may pose to your alfalfa.

Scouting for potato leafhopper starts after the first cutting of alfalfa (about the first part of June) till the first fall frost. You will want to use a potato leafhopper sequential sampling plan to determine if an infestation requires management or not. The first thing to do is determine the height of your alfalfa. Smaller plants are more vulnerable to potato leafhopper; thus there are different action thresholds for different heights of alfalfa. The second thing you will need to know is how to sample for potato leafhopper. A sample consists of a set of 10 sweeps of the net. A sweep is one pass in front of you as you walk through the alfalfa. The return swing is counted as another sweep. Sequential sampling reduces the time spent in each field and tells you whether to treat (management action) or not treat (no management action). Sequential sampling is particularly helpful in minimizing time required to make a management decision in situations where PLH populations are very high or very low. Use the following chart to determine potato leafhopper infestation levels.

Potato Leafhopper Adult

Write down the number of potato leafhoppers for each sample taken on the card. Add each sample to the next, keeping a running total of potato leafhoppers. You will need to take at least 3 samples using the sequential sampling method. On the sequential sampling card “N” is defined as no treatment (no management) needed at this time and “T” is defined as treatment (management) needed within in a week. If the sample is smaller than the “N” number stop and scout 7 days later. If the number of leafhoppers is larger than the “T” number then management action needs to be taken within a week. If the number of potato leafhoppers fall between “N” and “T” then continue and take the next sample till a decision can be determined. A guide with a printable version of the sequential sampling chart can be found at: http://www.nysipm.cornell.edu/publications/plh.pdf


Source: Growing Alfalfa the IPM Way

Be Ready for Potato Leafhopper before the damage occurs!

Ken Wise-NYS IPM

As temperatures increase and weather fronts roll through NY, so does the risk of potato leafhopper populations reaching levels damaging to alfalfa yields and quality. Do you know what to do if a field reaches an action threshold for potato leafhopper in alfalfa? Here are the management options for potato leafhopper in alfalfa!

Option 1: Early Harvest

You can harvest the alfalfa early to control potato leafhoppers if the field is within a week to ten days of a scheduled harvest. By harvesting the alfalfa early, you’ll prevent potato leafhopper from reaching infestation levels that can cause yield and quality loss to the forage. Make sure that the whole field is harvested at the same time. If a field is not clean harvested then the alfalfa that has not been cut will serve as a refuge for potato leafhoppers and can re-infest; thus severely damaging alfalfa re-growth.

Option 2: Use an Insecticide

To protect yield and health of new seedings and established alfalfa, insecticide control can be warranted when a field is not within a week of harvest. For selection of an insecticide consult the current issue of Cornell Guide for Integrated Field Crop Management. Remember to read the label and be aware of blooms, bees and the days until harvest restrictions.

Option 3: Plant Potato Leafhopper Resistant Alfalfa

A third option for control is planting potato leafhopper resistant alfalfa. Obviously, it is a little late for this season’s crop but something to consider for future seedings. Research has shown that potato leafhopper resistant alfalfa is consistently higher in quality than susceptible alfalfa varieties with or without potato leafhopper pressure. PLH resistant varieties yields are comparable and generally better than susceptible varieties when PLH are present. A bonus benefit is that currently available alfalfa varieties with PLH resistance have come down in price over the past several years.

For management information, check our on-line IPM video: Time to Scout for Potato Leafhopper in Alfalfa

Scouting Soybean Aphid

Keith Waldron-Cornell University, NYS IPM

Soybean aphid (SBA) appeared this week in central NY. The economic threshold is 250 SBA’s/ PLANT. It is the time to begin checking soybean fields for soybean aphid.

What to look for:

Check the under surface of leaves for presence of very small aphids. If present, the aphids are usually seen in small clusters near the leaf veins. They are tiny, 1/16″ long at their largest, with distinctive black cornicles (tail pipes).  Soybean aphids are the only aphids to successfully colonize soybean plants. These aphids may or may not have wings.

Infested fields may also be stunted, have areas leaf curling and the sticky “honey dew” residue associated with a high aphid population and relatively low numbers of natural enemies. A large colony of soybean aphids often includes white, shed skins and brownish carcasses killed by fungal pathogens. Plants with very high SBA populations can also attract ants that can be seen on and in the plant canopy.

190 soybean aphids on leaflet

Soybean Aphids

Threshold guideline:

SBA threshold guideline is 250 soybean aphids per plant if populations are actively increasing on 80% or more of the plants prior to early pod fill (R4). The 250 SBA / plant action threshold is based on an average of aphids per plant over 20-30 plants sampled throughout the field. This threshold incorporates an approximate 7-day lead time between scouting and treatment to make spray arrangements and handle weather delays. Midwestern research has found that treating earlier than this threshold in most cases does not pay for itself. When scouting the early vegetative stages of soybeans for soybean aphid, it is just as important to watch for the aphid’s natural enemies, including ladybugs, syrphid fly larvae, parasitic wasps, and fungal pathogens.

If fields are approaching threshold, a follow up field visit is recommended within a week, particularly following rain storms, to determine if SBA populations are increasing, assess potential impact of natural enemies and re-assess if rains have affected aphid numbers on plants.


Insecticides labeled in NY for treatment of SBA’s are shown in Cornell Guide for Integrated Field Crop Management. If fields are treated, re-evaluate fields for SBA numbers at least 7-10 days following treatment. Information from any treat / no treat side-by-side comparisons is always appreciated.

NYS Western Bean Cutworm Report for Field Corn 2018

The 2018 Western Bean Cutworm (WBC) Monitoring program is underway and WBC moth collections have begun. Western Bean Cutworm (WBC) is an emerging pest in NY with the potential to cause substantial damage to corn, Zea mays and beans, Phaseolus vulgaris. WBC is native to North America and has historically been a pest of corn and dry beans in the high plains region of the western US.  WBC larvae feed on developing corn kernels, bean pods and seeds. Larval feeding damage causes direct yield losses and can increase subsequent risk of ear mold issues including infection by mycotoxin producing fungi.

WBC moths were first confirmed in Pennsylvania and western New York in 2009, one year after they had been detected in Ontario, Canada.  Extensive monitoring during 2010 – 2017 has determined that WBC moths are well distributed across these areas and have expanded their range into Quebec and parts of Northeast.

NY WBC populations have increased annually since 2010 as indicated by the average and maximum range in number of WBC moths captured per location (Table 1). A total of 19, 476 WBC moths were collected in 2016 less than the 20,844 collected in 2015, compared to 11,353 collected in 2014, and more than 3 times the 6,110 WBC moths collected in 2013. In 2017 we caught more moths in the pheromone traps than any other year. It is 14,866 more moths than the highest pervious year (35,710 moths) Location and relative moth counts for 2017 trap sites are shown in Figure 1. On average, higher WBC counts continue to be captured in northern and western counties with the majority of high trap counts occurring in locations north of the NYS thruway (Interstate 90).

Table 1. New York Western Bean Cutworm 2010 – 2017 Collection Data Summary*

  2010 2011 2012 2013 2014 2015 2016 2017
No. Counties 29 37 44 39 41 39 40 40
No. Traps 54 67 88 89 96 91 101 101
Avg. No. WBC / Trap 13 23 42 66 117 266 193 361
Range in Totals 0 – 99 0 – 165 0 – 344 0 – 853 0 – 1019 0 – 1688 0 – 1662 0-2464
Peak Flight 2-Aug 2-Aug 25-Jul 21-28-Jul 3-Aug 2-Aug 31-Jul 8-Aug

*Data compiled from WBC trap catch information provided by field corn, sweet corn, and dry bean monitoring networks across NY.



Figure 1. Western Bean Cutworm trap location and accumulated moth capture for 2017.


To keep watch on WBC populations and help determine this season’s risk of potential impact WBC pheromone traps are again being monitored across the state by a dedicated network of cooperative extension, agricultural consultant and producer volunteers. WBC trap deployment began in June. WBC numbers are beginning to trickle in indicating moth emergence has begun. Peak WBC moth flight activity is anticipated towards the end of July or early August. As of today (7/20/2018) we have caught about 270 moths across the state. It will pick up as the summer progresses.


Western bean cutworm updates for sweet corn and dry beans will be available at this blog throughout the season and the NYS IPM Sweet Corn Pheromone Trap Network Report.

Clipboard Checklist

Keith Waldron, NYS IPM 


*Walk fields to check general field condition, weed 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.

Small Grains:
*Monitor spring small grains for signs of Fusarium Head Blight, foliar diseases

*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 crop growth stage, 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
*Review/Plan rotations


* 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