Elson Shields, Entomology, Cornell University, Ithaca, NY
Corn rootworm (CRW) is the number one pest of corn in both NY and the U.S. Recent NY field data are showing that the biocontrol nematodes being released against alfalfa snout beetle are also having an impact on CRW after the field is rotated from alfalfa into corn. Research in NNY for the past 18 years has shown that a single field application of persistent biocontrol nematodes inoculates the field for multiple years and across rotations. In 75 fields following a typical alfalfa-corn rotation, not only did the biocontrol nematodes persist for multiple years at sufficient populations to suppress soil insects, but biocontrol nematode populations were higher after 4-years of corn than in the alfalfa before being rotated to corn. These results suggested the biocontrol nematodes were attacking CRW during the corn years of the rotation.
In test plots on the Cornell Musgrave farm, biocontrol nematodes applied in 2014 in continuous corn production prevented CRW larval feeding damage in 2016 at the same level as the best BT-CRW traited corn (Fig 1 & 2). Even though the CRW populations were sub-economic in 2017 and 2018, the biocontrol nematodes continued to persist at levels where they can react to an economic population of CRW larvae. We are anticipating an economic population of CRW larvae in the research plots in 2019. Similar results were recorded in a cooperative study with Texas A&M in Dalhart, Texas under extremely heavy CRW pressure. Cornell joint research projects against CRW continues in 2019 in NY, Texas, and Michigan with new cooperative research plots planned in Pennsylvania, Vermont and SW Kansas. Research on impact of these biocontrol nematodes on wireworms in the Hudson Valley has shown reduction in the soil populations of these soil insects along with reduced root injury in areas where these biocontrol nematodes have been established.
The Shields’ lab at Cornell has just been awarded a NE SARE grant to work with NY corn producers interested in inoculating a corn field with native biocontrol nematodes to replace other CRW management practices such as Bt-CRW corn varieties. Full establishment of the biological control nematodes requires a full year and will be fully effective in year 2. Farmers interested in apply biocontrol nematodes to corn for corn rootworm control have the opportunity to participate in a NE SARE grant for the next 3-years. This grant is focused on the biological control of corn rootworm with persistent biocontrol nematodes. Participants will receive a reduced biocontrol nematode price for their first field entered into the program. Biocontrol nematodes are applied through conventional spray equipment in 50 gallons of water per acre. In order to use the spray equipment, 1) all screens and filters need to be removed; 2) sprayer needs to be cleaned similar to changing of herbicides and 3) Nozzles need to be replaced to fertilizer stream nozzles similar to TeeJet 0015. The cost of the biocontrol nematodes for fields participating in the NE SARE program will be $50/ac which is a 50% reduction in the price of the biocontrol nematodes. The application window for biocontrol nematodes on corn is between pre-planting and growth stage V4. If farmers are interested in participating in the application of biocontrol nematodes on their fields for CRW control, they need to contact the Shields’ Lab no later than 45 days prior to a planned application.
For more information please contact your area CCE specialist:
Ken Wise & Jaime Cummings, NYS IPM, Cornell University
Many species of birds, including crows, ravens, black birds, starlings, grackles, Canada geese and wild turkeys, are a pest problem annually for corn growers in several areas in New York State. Many growers have issues with birds picking corn seed and seedlings out of the ground after planting.
Birds can greatly reduce corn plant populations in fields. Many farmers indicate that they do not achieve high yields in fields with high bird pressure. Bird damage is not easily predictable. But small fields surrounded by roosting areas with soils that are compacted or gravelly, and where seed is planted shallow tend to be most susceptible. However, damage can be observed in any corn field where a random flock of birds decides to feast. Many farmers have this problem annually, and struggled to find effective options to keep birds out of the fields.
A biological seed treatment, called Avipel Shield, developed by Arkion Life Sciences, is marketed to repel birds from feeding on newly planted corn seed and seedlings. The active ingredient is “anthraquinone”, which is a plant extract found in aloe, rhubarb, buckthorn and more. The corn seed is coated with Avipel Shield, which is also compatible with other conventional seed treatments. As it states on the product’s website, “Avipel Shield (AQ) creates a powerful negative intestinal reaction in all birds”. This product does not harm the birds, but causes them to forage elsewhere. The product can come pretreated on seed, or the farmer can apply it themselves.
Corn growers in NY were interested to know if this product really worked. Therefore, NYS IPM and CCE collaborators around the state conducted 3 years of research to determine the efficacy of this product for deterring birds from feeding on newly planted corn fields.
Methods and Procedures:
We worked cooperatively with nine CCE educators/specialists who organized 11 farms in eight counties (Schenectady, Delaware, Jefferson, Ulster, Green, Lewis, Oneida and Franklin) to implement this on-farm research project. Trials were established in fields that traditionally had a history of excessive bird damage to newly seeded field corn. Each trial involved a split-field design on 5 acres. Half of each trial (2.5 acres) was treated with Avipel Shield and the other half was not. A 97-day, multi-purpose triple-stacked hybrid was selected with a typical insecticide and fungicide seed treatment package from Dairyland (HiDF 3197RA) in order to minimize other possible variables from interfering with the research. Any remaining acreage of each field was planted to a hybrid of the farmer’s choice. Data was collected at each trial from each treatment at the V3 growth stage from two random samples in four quadrants of each treatment area. Plant populations were measured in each of the quadrants in 100 ft lengths of two consecutive rows. Observations on crop damage from birds were recorded at this time. Yields were recorded, when possible, for both silage and grain trials. For silage trials, scales and wagons/trucks were used to measure the wet plant weight of the entire treatment area (2.5 acres), or were hand harvested at five random locations in each treatment block, cut a 20’ row length at 10” above the soil surface. For grain trials, yield monitors were used to determine bushels/acre.
The results of the five replicated trials in 2016 showed that the seed treatment significantly reduced feeding by birds. On average, the plant population in the Avipel treated plots was 30,237 plants/acre, compared to 27,604 plants/acre in the non-treated plots, resulting in 2,632 more plants/acre in the Avipel treated plots. In 2017, there were 16 replicated trials, and the Avipel treatment resulted in significantly higher plant populations overall when compared to the non-treated control, with an average of 612 more plants per acre. In 2018, there were 20 replicated trials. Once again, the Avipel treatment resulted in significantly higher plant populations overall when compared to the non-treated control, with an average of 962 more plants per acre. With plant population data pooled from all three years of the study, the difference between the Avipel treatment and the control was highly significant (Figure 1). Despite the significant increase in plant populations in the Avipel treated plots, there was no significant difference in yield between the treatments. However, many factors account for end of season yields in field corn, including weather and other environmental factors.
Impacts and Observations:
In this study, crows were the main pest observed in the fields, but there were also turkeys, seagulls and red winged black birds observed. It is thought that the birds learn the effect of the product, and likely do not return to those fields in subsequent years, though this was not specifically measured in this study. The main impact of this research revealed that Avipel Shield helps maintain plant populations, especially in fields with high bird pressure. But, birds, like crows, are complicated in how they select where they want to roost and feed from year to year, making it difficult to predict bird damage.
One observation from this study is that there may have been an effect within the same field where Avipel-treated seed is planted next to the non-treated seed. The birds may have left and avoided the entire field after experiencing the Avipel, rather than seeking to feed on the non-treated half of the field. A second observation is that once the birds learned the taste of Avipel in certain fields, they did not return, and many of the fields used in this study were planted to the same trial each year. This may explain the low bird pressure in some fields.
Avipel Shield has since been registered for use in New York, and some of the growers involved with this project have decided to treat all of their corn with Avipel based on the results of participating in these trials.
This research was made possible with funding from the NYS Corn Growers Association and the NYS Farm Viability Institute, and with extensive assistance from CCE collaborators Aaron Gabriel, Kevin Ganoe, Jeff Miller, Mike Hunter, Dr. Kitty O’Neil, Joe Lawrence, Paul Cerosaletti, Dale Dewing and Dr. Paul Curtis.
Ken Wise (NYS IPM) and Mike Hunter (CCE North Country Regional Ag Team)
Western bean cutworm (Striacosta albicosta [Smith]) (WBC) was first discovered in New York State in 2009. It has been expanding its range from its origin in the high plains area of the US over the last 20 years. WBC is an insect pest of corn and dry beans, and can cause significant yield and quality losses to field corn grain. In other parts of the Corn Belt, it has become a pest causing significant economic losses in field corn. WBC is a Lepidopteran Noctuidae moth species that lays eggs on the upper surface of leaf just before tasseling (Fig. 1).
Once eggs are laid on leaves, they appear white and will turn tan, and then a purplish color before hatching (Fig. 2). The 1st instar larvae will eat their egg shells before finding other food and an area of protection from predators or parasitoids. The small larvae will move to the whorl and/or leaf axil, and they will eat pollen, tassels and silks (Fig. 3). By the 4th instar the larvae will bore into the corn ear and feed on kernels of corn (Fig. 4). One difference between WBC and other species of worm pests of corn ears (European corn borer, corn ear worm) is that you can find multiple worms in one ear. Other species are cannibalistic, and allow only one larvae to enter the ear, while WBC does not mind if there are several per ear.
One to several larvae per ear can really affect the yield. Once the larvae reach the 6th instar they drop from the plant to the soil surface, where they burrow into the soil and create a chamber where they will overwinter in a pre-pupa stage (Fig. 5). They will finish the pupation in late spring and early summer, and emerge from the soil from mid-July through mid-August with peak flights during the last week in July to the first week in August.
Since the discovery of western bean cutworm in New York in 2009, we have monitored its progression across the state. In 2010, we developed a WBC pheromone trap monitoring network. This network of Cornell Cooperative Extension Educators, crop consultants and agricultural professionals placed out bucket pheromone traps to capture moths each year from late June through August. A female WBC pheromone lure is placed in the trap which attracts and catches only the male WBC moths. Each week the number of moths are counted and reported by the location of the trap. These traps are deployed to monitor moth presence and determine the peak flight. Traps help us identify fields at risk and when scouting should take place, but we cannot use trap counts to determine when a field should be sprayed with an insecticide.
Since 2010, the population of the WBC in New York has increased exponentially. We started with 19 volunteers and 44 traps in 29 counties, and in 2018, we had 50 volunteers and 118 traps in 45 counties.
The total number of WBC moths captured per trap in New York by year are depicted in Table 1. In 2010 there were less than 15 moths caught per trap with a high of 99. In 2018, we had 118 traps that caught 39,290 moths with an average of 333 moths per trap. Some traps in Northern NY had 1000 to almost 3000 moths in a single trap. Northern NY is the hot spot for WBC, and the number of moths caught in this region of the state far exceeds the rest.
When looking at the average number of moths caught per trap, 67% of the traps caught more than 100 moths and only 15% caught less than 20 moths (Fig. 7). Jefferson County had a single seasonal trap accumulation of 2964 moths. The range of trap counts were 0 to 2964. While the average came down just a bit from 361/trap in 2017 to 333 /trap in 2018, we had many more traps in areas of the state that do not have the same pest population densities of Northern NY. This brought the average number of moths/trap down for the first time since 2016. In 2016, we had drought conditions that might have caused a reduction in population of WBC.
A very important aspect of managing WBC is knowing when peak flight occurs. The annual peak flights are outlined in Figure 8. From 2010 to present, the peak flight has ranged from the last week in July to the first week in August. By knowing the peak flight, you know when most of the moths will be laying eggs in pre-tassel corn because the female moths prefer to lay eggs on this stage of corn growth. And this peak flight time is when we should be vigilant about scouting for WBC egg masses and small larva.
The data is starting to show that the population is beginning to build up in areas of the state that have previously had lower populations of WBC. The data in Figure 9 indicates that the average number of moths caught per trap is increasing across the state outside of Northern NY. In time, WBC populations will likely rise across the state to the point that management will be needed for this insect pest. Widespread, high WBC populations in many areas of Northern NY have resulted in some corn fields being treated with insecticides to manage this pest.
While WBC damage to corn ears can be significant and may have detrimental effects on corn grain yield and quality, the economic impact on corn silage is less understood. For corn silage growers, determining whether or not this pest significantly impacts the yield or quality of the forage is critical to their decision making for managing this pest.
Scouting corn at the pre-tassel stage of growth is an important aspect of managing this pest. The economic threshold is 5% of plants having egg masses and small larvae. The 5% is an accumulated threshold, meaning that if in week one 3% of the plants have egg masses and the folowing week there are 2% more, this equals a cumulative 5%.
Current strategies available for control of WBC in corn are the use of foliar insecticides or selecting transgenic corn hybrids with the Vip3A trait. Foliar insecticide treatments are effective but can be difficult to correctly time applications. If a field is found to be over threshold for WBC, an insecticide should be applied only if fresh silks are present. If no tassel is present there is no reason to spray an insecticide because it would be too early and the larva will not survive. Once the larva make their way into the ear tip it is too late to spray as the insecticide will not come into contact with the larva. Currently, only corn hybrids with the Vip3A trait will provide control of the WBC. There have been reports from Michigan, Indiana, Ohio and Ontario, Canada suggesting varying levels of control of WBC with the Bt corn trait containing the Cry1F protein, (DiFonzo, C., Krupke, C., Michel, A., Shields, E., Tilmon, K. and Tooker, J; 2016). Based on 2016 to 2018 on farm research trials in Northern and Western NY, it was determined that incomplete control from the Cry1F trait was confirmed, (Hunter, M., and O’Neil, K.; 2018, 2017, 2016).
Acknowledgements: Thank you to Jaime Cumming (NYS IPM) and Marion Zuefle (NYS IPM) for editing and providing additional data for the article.
2018 New York WBC Pheromone Trap Monitoring Network: Thanks to cooperating growers for allowing us to use their fields for sample sites. Special thanks to the following individuals for their enthusiasm, dedication, excellent data collection and maintenance of the WBC trap network: Adam Abers, Brian Boerman, Chuck Bornt, Elizabeth Buck, Sara Bull, Paul Cerosaletti, Mike Davis, Janice Degni, Dale Dewing, Natasha Field, Cassidy Fletcher, Jennifer Fimbel, Aaron Gabriel, Kevin Ganoe, Jeffrey Gardner, Don Gasiewicz, John Gibbons, Ethan Grundberg, Mike Kiechle, Ariel Kirk, Jeff Kubeka, George Krul, Christy Hoepting, Mike Hunter, Amy Ivy, Joe Lawrence, Jodi Lynn Letham, Jen Masters, Laura McDermott, Carol MacNeil, Sam Meigs, Stephanie Melancher, Sandy Menasha, Jeff Miller, Anne Mills, Eric Nixon, Kitty O’Neil, Jessica Prospers, Bruce Reed, Teresa Rusinek, Erik Kocho-Schellenberg, Jack Steele, Abby Seaman, Keith Slocum, Paul Stackowski, Mike Stanyard, Dan Steward, Crystal Stewart, Allie Strun, Linda Underwood, Katherine Vail, Ken Wise, Anastasia Yakaboski, Glenn Yousey, Marion Zuefle, WNYCMA. The WBC Bt corn trials were made possible with support from both the New York Corn Growers Association and the Northern New York Agricultural Development Program.
Hunter, M., and O’Neil, K.; 2018 Evaluation of the Efficacy of Bt Corn for the Control of Western Bean Cutworm in NNY. Northern NY Agricultural Development Program. Cornell University (report forthcoming)