Armyworm Scouting and Assessment in Newfoundland & Labrador. Integrated Pest Management Research

Transcription

1 Armyworm Scouting and Assessment in Newfoundland & Labrador Integrated Pest Management Research Project Lead: Leah Madore Pest Management Specialist Department of Natural Resources 1

2 Acknowledgements I would like to thank the producers that took part in this monitoring project as well as the technicians that carried out field work; Peter Compagnon and Margaret Barnes. Also, others who helped include: Dr. Peggy Dixon, Dr. Carolyn Parsons and Todd Power of Agriculture and Agri- Food Canada as well as other various colleagues are thanked for all contributions, comments and suggestions that were made during this project and editing of this report. Department of Natural Resources 2

3 Table of Contents Executive Summary... 4 Introduction... 5 Funding & Partnerships... 6 Methodology Results & Discussion Conclusions References Appendix A Department of Natural Resources 3

4 Executive Summary During the summer of 2011 and 2012, armyworm (Mythimna unipuncta) devastated vegetable and forage crops across Newfoundland & Labrador. The estimated forage crop loss in 2012 is estimated at $2.5 Million. Although a sporadic pest, in the years in which they live up to their name they can cause extensive damage. The objectives of the project were to provide training on armyworm crop scouting techniques to Newfoundland and Labrador forage producers, evaluate arrival dates of the adult armyworm moths throughout Newfoundland and Labrador and to evaluate armyworm larvae populations throughout Newfoundland and Labrador. Pheromone traps were set-up mid-may at the chosen locations listed above. These were used to determine if large numbers of moths are moving up from the US on the storm fronts. Both a universal insect trap and a Heliothis trap were set-up at each location with armyworm pheromone placed inside to attract male armyworm Once adult moths were found in traps, weekly larvae assessments were conducted more thoroughly. Larval feeding was assessed during the site visits as well at other fields nearby. Scouting was conducted by randomly walking through fields and looking for feeding damage on timothy grass and host species of the armyworm. After feeding damage is found, a thorough investigation of the ground in those areas was completed to find the larvae that created the damage. Arrival of adult armyworm started the week after set-up of traps at all but one site. At sites that had high adult population trap counts, it was noticed that approximately six weeks after peak flights, there were high larval counts as well. It is important to note that other studies across Canada have found moths every month of the year, including Dec, Jan and Feb. These moths come in on the jet stream and/or storm fronts from Mexico, Texas and other warm areas, and drop down with wind currents. In NL, if they drop down in the winter, they will die, but they will survive, if minimal survival temperatures are met. Thresholds for armyworm adult populations can be measured on a Low-Medium-High scale. <6/week is low; ~ 12/week is medium and 20+ per week is high. Department of Natural Resources 4

5 Introduction During the summer of 2011 and 2012 the armyworm (Mythimna unipuncta) devastated vegetable and forage crops across Newfoundland & Labrador. The estimated forage crop loss during 2012 is estimated at $2.5 Million. Although a sporadic pest, in the years they live up to their name, they can cause extensive damage. They attack mainly grasses; including crops such as corn, forage grasses (timothy, fescues etc.) and small grains such as wheat, barley, and oats. Due to the economic losses that this pest may cause, it is an insect of interest for monitoring in NL. Forage producers and agricultural groups throughout the province have requested a scouting workshop to deal with the armyworm. This workshop included; how to properly assess adult arrival, larvae damage on crops, economic losses and action thresholds to control the armyworm. During this project, there will be relevant, local information for producers regarding arrival dates and crop scouting techniques for the armyworm in NL. This will provide producers with the knowledge to identify, assess infestation and to effectively apply control measures in order to avoid devastating economic loss. The objectives of the project were: To provide training on armyworm crop scouting techniques to Newfoundland and Labrador forage producers To evaluate arrival dates of the adult armyworm moths throughout Newfoundland and Labrador To evaluate armyworm larvae populations throughout Newfoundland and Labrador The project team included: Leah Madore, Pest Management Specialist Jane White, Crop Development Officer Peter Compagnon, Agricultural Technician, West coast Margaret Barnes, Agricultural Technician, East coast Amanda Green, Agricultural Development Officer, Labrador Dr. Peggy Dixon, entomologist and Dr. Carolyn Parsons, research assistant, Agriculture and Agri-Food Canada, St. John s Funding & Partnerships The Armyworm Scouting and Assessment in Newfoundland & Labrador project was funded by the Agriculture Research Initiative. In kind contribution was provided by Agriculture and Agri-Food Canada (AAFC), and numerous forage producers across Newfoundland and Labrador. Work was administered by the Newfoundland and Labrador Department of Natural Resources, aided by cooperating AAFC staff and producers. Methodology This project aimed to determine adult armyworm arrival dates and larval populations across Newfoundland and Labrador. The locations used for assessment included: Department of Natural Resources 5

6 The Goulds H&E Williams Dairy Farms Ltd. (Hector Williams) Torbay Leo Ryan s Farm (Leo Ryan) Lethbridge Beauty View Farms (Alvin White) Wooddale Glenfair Farms Ltd. (Art Gill) Cormack Rideout s Dairy Farm Inc. (Melvin Rideout) Maidstone New World Dairy (Brent Chaffey) Happy Valley-Goose Bay Grand River Farms (Frank & Joyce Pye) Adult moths arrive in spring on storm fronts from the southern United States. The number of moths that arrive in NL is variable. Moth presence will be determined through the use of pheromone traps placed in specific locations throughout Newfoundland and Labrador. If adults arrive, females can lay up to 2000 eggs (in clusters of ) in folded leaves or leaf sheaths. The larvae (caterpillars) pass through six stages (instars) where they get progressively larger, feeding on the leaves by night and hiding near the ground by day. Mature larvae (~1-2 ) crawl under leaf litter or below soil surface to pupate. Very few pupae survive the winter in Canada (Figure 1). Figure 1: Lifecycle of the Armyworm (egg, larvae, pupae, moth). Thresholds for the armyworm are 5.5 larvae per sq. ft. in most crops and 6 per linear foot of row for grain crops. Pheromone traps were set-up mid-may at the chosen locations listed above. These were used to determine if large numbers of moths are moving up from the US on the storm fronts. Both a universal insect trap and a Heliothis trap were set-up at each location with armyworm pheromone placed inside to attract male armyworm (Figure 2). Once inside, the vapour strip kills the adults in the trap. The traps were checked on a 7-10 day basis from May to October and population counts recorded. This information was relayed to forage producers in the area and they were advised to begin the crop scouting process. Department of Natural Resources 6

7 Figure 2: Heliothis trap (left) and a universal uni-trap (right) Once adult moths were found in traps, weekly larvae assessments were conducted more thoroughly. Larval feeding was assessed during the site visits as well at other fields nearby. Scouting was conducted by randomly walking through fields and looking for feeding damage on timothy grass and host species of the armyworm. After feeding damage is found, a thorough investigation of the ground in those areas was completed to find the larvae that created the damage. During the day, larvae curl up at the base of the plants they have been feeding on and may also be found under any debris at ground level. Identification of the larvae determined if the damage was in fact by armyworm. Figure 3: Feeding damage by Armyworm larvae. Department of Natural Resources 7

8 Results & Discussion A series of Armyworm Crop Scouting Workshops were held across Newfoundland (See Appendix A for presentation). The locations of the workshops were Lethbridge May 22nd, Attendees registered, Cormack May 28th, Attendees registered, and St. John s May 24th, Attendees registered. Forage growers were encouraged to attend a workshop in their area. These workshops included Armyworm identification, scouting & monitoring for Armyworm & field assessment after an Armyworm attack has occurred. The presentations prepared producers for arrival of this pest and how to properly manage if found. Producers understand economic thresholds and the management techniques for this pest. An infield training session was completed, which included how to assess and identify armyworm presence, infestation and crop damage through the use of pheromone traps and field scouting. Figure 2: Adult armyworm trap catches at the Lethbridge site. The peak flight of the adult armyworms at the Lethbridge Site (Figure 1) was on June 26/13. This peaked at 110 adults caught in both the heliothis and uni traps. Approximately six weeks later, considerable number of larvae were detected at this site. The total number of adults trapped by the Uni-trap from May to September was 121. The total number of adults trapped by the heliothis trap from May to September was 374. During larval monitoring, the highest count of larvae found was 50+ on August 8 th, This is approximately six weeks after the peak adult flight captured in the traps. It is important to note that during the larval monitoring at the Lethbridge site, most larvae found were dying/dead due to natural predation. This may be due to high levels of healthy bacteria/disease organisms, which is unique to this site. Department of Natural Resources 8

9 Figure 3: Adult armyworm trap catches at the Roache s Line site. The peak flight of the adult armyworms at the Roache s Line Site (Figure 3) was on June 26/13. This peaked at 50 adults caught in both the heliothis and uni traps. The total number of adults trapped by the Uni-trap from May to September was 74. The total number of adults trapped by the heliothis trap from May to September was 112. During larval monitoring, the highest count of larvae found was 7 on August 14 th, This is approximately six weeks after the peak adult flight captured in the traps. Figure 4: Adult armyworm trap catches at the Torbay site. The peak flight of the adult armyworms at the Torbay Site (Figure 4) were three count of two adults on June 11/13, June 18/13 and July 4/13. The total number of adults trapped by the Unitrap from May to September was six. The total number of adults trapped by the heliothis trap from May to September was zero. During larval monitoring, the highest count of larvae found was two on August 16 th, There were very small numbers detected at this site. Department of Natural Resources 9

10 Figure 5: Adult armyworm trap catches at the Cormack site. The peak flight of the adult armyworms at the Cormack Site (Figure 5) was on June 25/13. This peaked at 7 adults caught in both the heliothis and uni traps. The total number of adults trapped by the Uni-trap from May to September was 5. The total number of adults trapped by the heliothis trap from May to September was 14. During larval monitoring, there were no armyworm larvae found. Figure 6: Adult armyworm trap catches at the Maidstone site. The peak flight of the adult armyworms at the Maidstone Site (Figure 6) was on July 19/13. This peaked at 42 adults caught in both the heliothis and uni traps. The total number of adults trapped by the Uni-trap from May to September was 12. The total number of adults trapped by the heliothis trap from May to September was 88. During larval monitoring, there were no larvae found. Department of Natural Resources 10

11 Figure 7: Adult armyworm trap catches at the Cormack site. The peak flight of the adult armyworms at the Wooddale Site (Figure 7) was on June 28/13. This peaked at 12 adults caught in both the heliothis and uni traps. The total number of adults trapped by the Uni-trap from May to September was 4. The total number of adults trapped by the heliothis trap from May to September was 51. During larval monitoring, there were no larvae found. Figure 8: Adult armyworm trap catches at the St. John s site. The peak flight of the adult armyworms at the St. John s Site (Figure 8) was on July 11/13. This peaked at 76 adults caught in both the heliothis and uni traps. The total number of adults trapped by the Uni-trap from May to September was 30. The total number of adults trapped by the heliothis trap from May to September was 102. Department of Natural Resources 11

12 Figure 9: Adult armyworm trap catches at the Goulds site. The peak flight of the adult armyworms at the Goulds Site (Figure 9) was on July 11/13. This peaked at 126 adults caught in both the heliothis and uni traps. The total number of adults trapped by the Uni-trap from May to September was 80. The total number of adults trapped by the heliothis trap from May to September was 342. Conclusions Arrival of adult armyworm started the week after set-up of traps at all but one site. It is important to note that other studies across Canada have found moths every month of the year, including Dec, Jan and Feb. These moths come in on the jet stream and/or storm fronts from Mexico, Texas and other warm areas, and drop down with wind currents. In NL, if they drop down in the winter, they will die, but they will survive, if minimal survival temperatures are met Thresholds for armyworm adult populations can be measured on a Low-Medium-High scale. <6/week is low; ~ 12/week is medium and 20+ per week is high. At sites that had high adult population trap counts, it was noticed that approximately six weeks after peak flights, there were high larval counts as well. NL forage produces are encouraged to assess their land base that may be at risk of armyworm infestation and they should scout their forage and crop fields for the presence of armyworm caterpillars. Monitoring should take place on a weekly basis on all fields as a minimum precaution. Monitoring can be accomplished by inspecting mowing equipment as well as plants and the soil surface for caterpillars. Pheromone trapping can also be an aid in monitoring adult populations in the area. Monitoring methods can include: While walking fields, assess growth of grasses (and other host plants-) looking for feeding damage on leaves/stems and seed heads Checking the lower sections of plants can be important when monitoring. Department of Natural Resources 12

13 Caterpillars feed on lower leaves first, work upward and feed on the whorl leaves last When feeding damage is found, all field sections should be inspected by looking for larvae on the ground or under debris. Field edges can also be monitored for signs of migrating larvae. While walking through a field, check boots to see if there are caterpillars hanging on After cutting a field, thoroughly inspect mowers and tractors, as caterpillars may be hanging on equipment Pheromone trapping using heliothis trap, uni-trap, or wing traps may be used to monitor adult populations After cutting a pasture, grass should be removed as armyworm larvae may hide under debris. The presence of large numbers of birds in a field may also indicate that large numbers of armyworms are present. There are numerous control techniques that can be implemented if an infestation occurs: Cultural controls can include: Plow a deep ditch filling it with water to prevent larvae from migrating from one field to an adjacent area. Dig a deep ditch with vertical sides to prevent larvae from crawling out (holes, the diameter of a fence post, should then be dug every ten meters in the ditch, where caterpillars will congregate and they may be crushed (or sprayed). Biological controls can include: Larval populations are usually kept under control by parasitic flies and wasps and other insect predators and parasites. Armyworms are also attacked by viruses and fungi. In some instances, viruses have been known to cause armyworm populations to crash within a few days. Armyworm caterpillars infected with a virus appear limp and hang from plants after they die. Birds, toads and small mammals also feed on armyworms. Chemical control can include: Insecticides, these should be applied if larvae are at or above threshold levels and preferably when larvae are approximately 12 to 20 mm (1/2 to ¾ inches) long before most damage has occurred. Once larvae are mature, 30 to 35 mm (1.18 to 1.37 inches) long, they will have done most of their feeding damage and it would no longer be economical to apply a control measure. A control measure should be applied to the field edge, as a ten metre strip, to prevent armyworms from migrating to a neighboring area. Insecticides should be applied in the evening since armyworms prefer to feed at night. It is important to follow all precautions and directions listed on the pesticide label and ensure that the product is registered for armyworms on the specified crop. Pay particular attention to the required water volume to be used. Best control is achieved when using the highest water volumes. Department of Natural Resources 13

14 References Carolyn Parsons & Peggy Dixon Armyworm Factsheet. Agriculture and Agri-Food Canada. OMAFRA staff Insects and Pests of Field Crops: Cereal Insects and Pests. Available online at: Unknown. ND. Armyworm Factsheet. Center for Integrated Pest Management North Carolina State University. Available online at: Unknown Armyworm Fact Sheet. Government of New Brunswick. Available online at: Department of Natural Resources 14

15 Appendix A Figure 1: Armyworm factsheet prepared by Dr. Carolyn Parsons and Dr. Peggy Dixon, Agriculture and Agri-Food Canada for the Dairy Farms of NL meeting August Department of Natural Resources 15

16 Figure 2: Armyworm Scouting Workshop Presentation, prepared by Leah Madore for the Armyworm Scouting Workshops May Department of Natural Resources 16

17 Figure 3: Armyworm Factsheet, Government New Brunswick. Figure 4: Memorandum, Armyworm Scouting Memo sent to forage producers of NL. Memos were sent May 2013, June 2013 and August Department of Natural Resources 17