The NYS IPM Field Corn Pheromone Trapping Network has started trapping black cutworm (BCW) Agrotis ipsilon and true armyworm (TAW) Mythimna unipuncta moth flights in NYS. While it seems like it might be early, we have caught BCW and TAW moths this week in Western, NY in pheromone bucket traps. These moths migrate north on weather fronts from the southern US every year. Both BCW and TAW prefer feeding on grasses, such as grassy weeds, hay fields, small grains and corn.
Even though the number of moths caught this week were low, it indicates that they have arrived. From this point forward, we can set the “Biofix Date”. The biofix date is the point where we start to calculate the number of BCW and TAM degree-days. We can predict when the eggs that were laid by moths will hatch. Degree-days are calculated by taking the high and low temperature each day and averaging them from the biofix date. Next, subtract the base temperature of 50 degrees Fahrenheit, and this will give you the daily degree-days. Each day, add the number of BCW degree days and this will give you a total. When this reaches 90 BCW degree-days and 113 TAW degree-days, the eggs will start to hatch.
High Temperature + Low Temperature/2 – 500 F = daily BCW degree days
The easy way to calculate this is to use the NEWA Degree Day Calculator. This will calculate the degree-days from a weather station near your farm. Below is the information on degree-days for the lifecycle of BCW and TAW.
A large number of moths in a trap does not necessarily mean there is going to be damage in your corn. It will depends on where the moths lay eggs. If a trap near your farm has a large number of moths, it would suggest it is time to scout for larvae and signs of feeding damage.
A good time to start scouting is when you take plant population counts. BCW damage is easy to identify. The larvae will cut the plant near the base at the soil surface, while TAW will feed from the edge of the leaf to the mid rib.
BCW and TAW larvae are primarily nocturnal or night feeders. Normally, you will not see them during the day. BCW larvae are ½ inch to 2 inches. They appear as greasy gray with darker raised spots on each segment. They normally hide in the soil near the base of the corn or under residue that might be on the surface.
TAW larvae range from ½ to 1.5 inches long. They have orange and white strips running along the side. They also have a white strip running down the back. TAW will hide under surface residue, in the whorl of the plant or in cracks in the soil.
If you are at threshold, and the larvae are still small, try to treat only the infected corn and a 20 to 40 foot border around the area. When the larvae are large (1.25 inches +) they are harder to kill with an insecticide, and they will pupate soon. When pupating, they will stop feeding.
One of the issues with BCW and TAW is that there can be multiple flights on different weather fronts throughout the spring. This can cause multiple infestations with different sizes of larvae in a field. Still follow the economic threshold, and manage if needed.
Our pheromone-trapping network has 25 traps of each BCW and TAW placed in 19 counties across the state. The counts and degree-days for many locations across NY will be published weekly starting later in April in the NYS IPM Field Crops Pest Report .
The full version of What’s Cropping Up? Volume 30 No. 2 is available as a downloadable PDF on issuu. This issue includes links to COVID-19 resources on the back page. And as always, individual articles are available below:
Jaime Cummings and Ken Wise (NYS Integrated Pest Management Program), Mike Hunter, Mike Stanyard, Aaron Gabriel and Kevin Ganoe (Cornell Cooperative Extension), and Michael Dorgan (NYSDAM)
Annual funding in the Plant Protection Act 7721 supports the Cooperative Agricultural Pest Survey (CAPS) pest detection program, led by the USDA Animal and Plant Health Inspection Service (APHIS), to safeguard against introductions of potentially harmful plant pests and diseases. These surveys ensure the early detection of potentially invasive species that could negatively impact U.S. agriculture and/or environmental resources. The NYS Department of Agriculture and Markets (NYSDAM) works with APHIS to prioritize the potentially invasive species to monitor in economically important commodities in NY each year. In 2019, NYSDAM partnered with the NYS Integrated Pest Management (IPM) program to coordinate a soybean CAPS survey to monitor for two potentially invasive moth species, as well as to expand monitoring of the soybean cyst nematode across New York soybean production areas.
The overarching goal of the CAPS program is to monitor for species that shouldn’t be here, and to confirm that they still aren’t in NY or even the U.S. These surveys are often the result of cooperation among state and federal employees, such as APHIS pest inspectors, NYSDAM inspectors and extension specialists. This ‘boots on the ground’ approach allows for broad coverage of the surveys across the state involving many individuals with agricultural and pest identification expertise.
For the 219 soybean CAPS survey, two moth species that are already problematic elsewhere in the world, but not known to exist in the U.S. were selected. The Golden Twin Spot moth (Chrysodeixis chalcites), which currently causes yield losses in Africa, Europe, the Middle East and Canada, has a larval stage known as a ‘looper’ which can cause significant damage to soybeans, tomato, cotton, tobacco, beans and potatoes (Fig. 1). Feeding by the loopers can result in defoliation, and they can also cause foliar damage due to rolling leaves with webbing for nests. The Silver Y moth (Autographa gamma), which is already a concern in many countries in Asia, Europe and Africa, also has a caterpillar larval state that can cause significant damage to soybeans and many other agronomically important crops, including beets, cabbage, hemp, peppers, sunflower, tomato, potato, wheat, corn and wheat (and many more) (Fig. 2). These caterpillars also defoliate and harm leaves through rolling and webbing. Given how potentially damaging an introduction of these pests could be to U.S. agriculture, it’s important that we are vigilant in our efforts to monitor for them and ensure they aren’t in NY.
In addition to monitoring for these two moth species, we also prioritized a pest that has very high potential to affect soybean yields in NY, and one that has thus far only been confirmed in one field in NYS. The soybean cyst nematode (SCN) is considered the number one pest of soybeans nationally and globally, causing an estimated 109 million bushels of yield loss in the U.S. in 2017. Extensive collaborative sampling for this pest from 2014-2017, supported by the NY Corn and Soybean Growers Association and Northern NY Agricultural Development Program, was coordinated by Cornell University and Cornell Cooperative Extension programs. Over the four years of the SCN survey, numerous fields in 17 counties were sampled, and one field in Cayuga County was identified as positive for SCN in 2016, albeit at very low levels (Fig. 3). Though it’s promising that SCN wasn’t identified widely across NY, we are fairly confident that it is very likely in many more than just one field in one county. Given the potential impact this pest could have on NY soybean (and dry bean) production, we decided to include this pest in the 2019 CAPS survey.
Six collaborators (Jaime Cummings and Ken Wise of NYS IPM, and Mike Stanyard, Mike Hunter, Aaron Gabriel and Kevin Ganoe of CCE) spent part of their typical summer soybean scouting efforts from western, to central, to eastern and northern New York setting up and checking pheromone traps intended to monitor for the Golden Twin Spot moth and Silver Y moth (Fig. 4). They communicated the importance of these surveys to cooperating farmers who agreed to host these traps in 25 fields across the state. Any suspicious moths caught in the traps are submitted to the Cornell Insect Diagnostic Clinic for thorough identification. Thus far, we have not caught any Silver Y or Golden Twin Spot moths. And that’s good news! As the growing season winds down, we will collect soil samples from the same 25 fields for SCN testing at the SCN Diagnostics laboratory.
Most corn and soybean growers in New York plant seed treated with insecticides. But are those treatments really needed in every field? The recent scrutiny on neonicotinoids (aka: neonics) causing harm to pollinators has brought this question to the forefront. Given all the negative attention that neonicotinoid have received in the media in recent years regarding pollinator health, it’s no surprise that they are on the chopping block in some NY legislative bills. These bills follow similar bans on neonics that have already taken place in Europe and Canada. Neonics have a bad reputation as having negative effects on bee health. Think about all the news you’ve seen or heard about the “bee-pocalypse”. And, it’s true that they can be lethal to bees and other beneficial pollinators, especially if applied to crops at incorrect timings or under the wrong conditions. They are insecticides, after all, and they are effective at killing insects, the good ones and the bad ones. But, let’s not forget about the bad ones they are intended to target to help farmers raise healthy and productive crops to feed livestock and all of us. It’s important that we consider both the positive and negative effects of these seed treatments when determining an overall need and value in our agricultural systems.
Neonic insecticides are used in many cropping systems, from fruits and vegetables to ornamentals to corn and soybeans to protect against some troubling pests. Neonics are available as seed treatments, soil drenches or foliar sprays to various crops, depending on the target pests and formulation of the products. And farmers everywhere have been using them for years, often as part of an integrated pest management program, to help minimize losses to some destructive pests. They were so widely adopted because they are effective pest management tools and because they were perceived as having a reduced overall negative impact on the environment and human health compared to many of the older insecticide chemistries, such as the organophosphates. But then it became apparent that these neonics, though safer for human health than many other insecticides, were taking a toll on beneficial insects, especially our bees that we rely on for pollinating many of our important food crops. And we need to pay attention to that issue and determine ways to mitigate those risks.
As mentioned above, neonics are used in various ways in many cropping systems. But their use as corn and soybean seed treatments has received a lot of attention because of the known potential for the neonic seed treatments to drift off-target as dust during planting. Because corn and soybeans cover such vast acreage in NY and across the country, mitigating these risks could potentially have a large impact on reducing bee mortality. Therefore, these seed treatments seem a likely, and potentially easy target for negative attention when folks start looking to reduce overall neonic usage. In response, the seed and seed treatment industries working with the EPA, USDA and other organizations started looking into ways that they could reduce the negative impacts that neonic treated corn and soybean seed could have on bees. In 2013, the EPA held a Pollinator Summit to focus on reducing exposure to dust from treated seed. Much research went into this focus group with collaborations between industry, academia and governmental regulatory agencies to address the off-target movement of dust from planting neonic treated seeds. I encourage you to read all the details for yourself regarding what they did and what they discovered in the Dust Focus Group and the Seed Treatment Group. For the sake of this article, I will briefly summarize their findings, conclusions and recommendations:
Start with clean, quality seed with minimal dust to begin with – many major seed companies have high standards for starting with clean seed which allows seed coating to better adhere, resulting in less dust.
Use improved polymers for adhering treatments to seed coats: seed coating technologies have improved dramatically over the years, meaning that less active ingredient ‘falls off’ the seed coat.
Use bee-safe seed lubricants: this minimizes the dust moving to off-target plants. New seed coating polymers and polyethylene wax lubricants for talc replacement can result in 90% total dust reduction and 65% active ingredient reduction in the dust.
Eliminate flowering weeds in and around fields prior to planting – this reduces the number of flowers that may accidentally have neonic dust that bees may forage on. The goal of many field crop growers is to ‘start clean’ meaning that they often try to minimize or eliminate competition from weeds prior to planting.
Be aware of wind speed and wind direction at time of planting – be a good neighbor. Avoid planting on the windiest days (when possible) and be aware of nearby bee colonies and wind direction. There are actually apps available to connect bee keepers with farmers to raise awareness of pesticide applications and locations of bee colonies.
Re-direct the exhaust flow of vacuum planters downward to minimize off-target movement of dust. Simple modifications can be made to some planters to re-direct the flow of the exhaust down toward the soil, which can significantly reduce dust movement. (Many planters don’t exhaust, and most air seeders already exhaust downward).
Follow labeling instructions for handing, storage, planting and disposal of treated seed and containers.
The findings, improvements and recommendations from this summit can greatly decrease the risk of negative effects of dust from neonic seed treatments on pollinators. However, some people are also concerned about neonics that might move through soil or water showing up in water and non-target plants. Because of these issues, neonic seed treatments might still be banned on corn and soybean in NY, so growers are concerned.
Neonic seed treatments come standard in just about every bag of corn and soybean seed planted. Some say we do need them, others say we don’t. If we look back in history a few decades, before the neonic seed treatments became available, farmers in NY struggled with early season pests like the seedcorn maggot, which can significantly reduce stand counts (and yields) under high pest pressure. The seedcorn maggot is favored by situations with actively decomposing organic matter, such as manure applications and terminated cover crops. Both of these situations are quite common in NY corn and soybean production systems. But, since the neonic seed treatments became so widely used, the seedcorn maggot issues have decreased dramatically, and possibly faded from memory.
But it still begs the question: Do we have pest pressure that warrants neonic seed treatments on the vast majority of our acres of corn and soybean every year? That is a good question. From an integrated management perspective, it’s never recommended to rely so heavily on one tool in the tool box for as long as we have with these neonics. We know that our insect pests can develop resistance to insecticides, just like weeds develop resistance to herbicides. There is also some evidence from various academic studies showing that the neonic seed treatments can negatively impact predatory insects, such as ground beetles, and other beneficial insects that serve as natural biological control of some of our other pests, such as slugs.
Given those reasons, it seems like it might be a good idea to reduce our dependence on neonic seed treatments, and only use them in situations where we know we need them, right? But, on the other hand, it’s important to keep in mind that, for now at least, it’s not easy to buy corn or soybean seed without a neonic as part of the seed treatment package. It’s very efficient and economical for the seed industry to include these standard treatments on their seed, and it’s also important for their liability for the guarantees they may offer farmers who purchase their seed. Not to mention that it’s not easy to anticipate when and where we need the neonic seed treatments each year. Sure, we know that fields with a history of manure and/or cover crops may be more likely to have seedcorn maggot issues, but there’s no guarantee they won’t also show up in a clean, tilled field. And, once the crop is planted, it’s too late to scout and determine whether or not the seedcorn maggots are going to be a problem. This unpredictability is why the neonics are used as an ‘insurance plan’ against these sort of pests.
This conundrum is why this is such a highly polarizing debate, and why the proposed legislative bans have some farmers riled up. It’s not that farmers want to use or pay for any more pesticides than they need, but the risk can be too high for their bottom line to just stop using them altogether. We need local research to back up any claims for or against the use of insecticidal seed treatments in corn and soybean production, and specifically the need for neonics. Much of the research from other states shows that they may not be necessary after all, because they don’t seem to cause a yield benefit. But, upon closer inspection of some of those results, many of those trials didn’t have measurable insect pest pressure to produce meaningful comparisons of treatments. And, many of the areas where those trials were conducted do not have the same practices with high organic inputs from manure and cover crops that many NY farms do.
So, it’s complicated. A great deal of pollinator risk research is being conducted at Cornell, including a risk assessment of neonic use. The results of that assessment could influence the future of legislation on the availability or restriction of these products. We know the dust from the neonic seed treatments poses a potential threat to pollinators (especially bees). But we also know from the EPA pollinator summit that there are ways to mitigate those risks through improved seed coating and seed lubricant technologies, which have been widely implemented. However, we still don’t know if there are other risks from these seed treatments, and we need more concrete evidence to know whether or not these neonic seed treatments are really necessary in such a large percentage of our NY corn and soybean acreage.
That’s why we decided earlier this spring to coordinate five statewide large-scale, on-farm trials with NYS IPM and Cornell Cooperative Extension specialists to try to evaluate the effect of these neonic seed treatments on 1) plant populations, 2) yield, and 3) how they compare to the anthranilic diamide seed treatments which could potentially replace them if the neonics are banned. These corn silage trials will be located in eastern, western, northern and central NY, all on farms that have typical NY cropping practices that incorporate manure and/or cover crops. Stand counts will be taken to measure plant populations and to determine insect pest pressure, and yields will be measured to compare the three seed treatments: 1) neonic + fungicide, 2) diamide + fungicide, and 3) fungicide only.
Regardless of our results, we will need multiple years of study to better characterize the pest pressure. Ideally, we would determine methods to predict and monitor seedcorn maggot pressure in individual fields and years for exploring biological, cultural and genetic means for suppressing these insects. However, this has proven challenging, as evidenced by the current situation in Canada.
Stay tuned for the results of these studies later this fall. And, I want to extend my sincere gratitude to all parties involved for coming together to conduct this research on extremely short notice. Thank you to Seedway for donating the seed, to Syngenta for donating the seed treatment products, to the participating farmers who are taking time out of their busy schedules to plant and harvest these trials, and to our CCE and PRO-Dairy collaborators (Joe Lawrence, Mike Hunter, Mike Stanyard, Aaron Gabriel and Janice Degni) for volunteering their time to conduct this important research. THANK YOU!!!
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