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Wisconsin and much of the United States endured an extended period of dangerously hot weather this week. Afternoon heat index values reached 100 to 115 degrees in parts of the state, with the most intense heat of the season occurring August 22-24. In addition to curbing alfalfa, apple, and potato harvest activities, the searing temperatures and high humidity levels kept DATCP field staff indoors on the hottest afternoons, slowing down completion of late August field surveys and inspections.
Meanwhile, the summer drought persisted throughout the state. The U.S. Drought Monitor released August 22 reports that 78 percent of Wisconsin is in moderate to exceptional (D1-D4) drought and 13 percent of the state is in extreme to exceptional (D3-D4) drought. Although drought improved by one category for much of southern Wisconsin after 2-4 inches of rain fell mid-month, longer term deficits remain. Precipitation deficits since June 1 are 4-6 inches in the severe (D2) drought area and 6-8 inches in the extreme (D3) drought area, which is about 50% of normal.
Cooler weather is expected to return for the weekend, but little or no precipitation is predicted over the next week and another hot spell is in the forecast for early September. Drought conditions are likely to continue for the foreseeable future.
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DATCP’s annual corn rootworm survey continued this week. Preliminary results show an overall decrease in beetle pressure as compared to 2022, although counts remained relatively high in the south-central and southeast parts of the state. Surveys in the south-central district found an average of 0.9 beetles per plant, a decline from 1.2 beetles per plant in 2022 yet still above the economic threshold of 0.75 beetle per plant. Similarly, the average recorded for the southeast district was also high at 0.8 beetles per plant.
In contrast, the survey found a pronounced drop in beetle pressure in southwest and east-central Wisconsin. The 2023 averages recorded for these two districts were 0.5 and 0.2 beetle per plant, respectively. In 2022, the averages were far higher at 1.3 beetle per plant in the southwest counties and 1.1 beetle per plant in the east-central area.
Sampling has been completed in 204 of the expected 229 fields and will be finalized by the end of the month. Continuous corn in at-risk areas should be scouted in the next two weeks to evaluate both adult rootworm pressure and the performance of Bt trait packages. |
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Western bean cutworm moth flights have subsided at pheromone trap monitoring locations. As of August 24, the state total count is 9,309 moths in 42 traps (222 per trap average), a considerable increase from the 4,804 moths in 36 traps (133 per trap average) collected last year and the highest state average count since western bean cutworm trapping surveys began in 2005. The highest individual count for the season was 850 moths near Princeton in Green Lake County, while nearly half of the sites recorded cumulative counts above 200 moths per trap for the season.
All western bean cutworm traps may be removed at this time. The DATCP Pest Survey Program wishes to extend its appreciation to all the volunteers who monitored traps again in 2023. THANK YOU to our cooperators for making this survey possible.
For regional western bean flight data extending across the northeastern U.S. and adjacent Canadian provinces, please see the Great Lakes and Maritimes Pest Monitoring Network (select WBC tab). |
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Late-season corn earworm moth migrations into Wisconsin escalated this week. Locally heavy flights were reported from the Beaver Dam (586 moths), Mayville (695), Pardeeville (225 moths), and Ripon (203 moths) monitoring locations, while eight other sites from Dane to Marathon counties collected fewer than 50 moths per trap. A cumulative total of 1,914 moths have been captured in 12 pheromone traps as of August 24.
The latest corn earworm activity signals that egg laying is likely to intensify with this late-season migration and the risk to fresh market and processing sweet corn will persist into September. |
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Detection efforts for the invasive spotted lanternfly and its preferred host, Ailanthus altissima (tree-of-heaven) are underway in southern Wisconsin. As of August 24, DATCP staff have conducted 27 miles worth of visual survey, spanning 14 high risk introduction sites. These surveys will continue into the fall and wrap up following southern Wisconsin’s first hard frost event. Spotted lanternfly has not yet been found in the state, but with recent detections in Indiana and Michigan, prevention and early survey efforts have become even more imperative for keeping this damaging “hitchhiker” insect out of Wisconsin.
Spotted lanternfly is one of the fastest-spreading exotic pests in U.S. history and has invaded 14 eastern U.S. states since first arriving in Pennsylvania in 2014. Established populations have so far been found in Connecticut, Delaware, Indiana, Maryland, Massachusetts, Michigan, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, Virginia, and West Virginia.
While these infested states have enacted quarantines to contain spotted lanternfly, the adult, nymph and egg stages move easily on firewood, tires, campers, vehicles and outdoor gear, and can be accidentally carried by tourists during summer and fall travel. Wisconsin’s southeast I-41 and I-43 corridors northward to Door County are considered especially high-risk for introduction. Grape vines in particular are a favored host, making vineyards likely sites for early infestations.
Below are measures to reduce the risk of carrying spotted lanternfly into Wisconsin and preventing its spread:
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Check your vehicle: Before leaving a state where spotted lanternfly is known to occur, inspect vehicles, campers and equipment for eggs or insects. Check doors, sides, bumpers, wheel wells, grills, and roofs. If found, immediately destroy the eggs or insects. At this time of year, the older nymphs (red and black with white spots) and adults are the life stages most likely to be observed.
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Remove host trees: Spotted lanternfly shows a distinct preference for tree-of-heaven or Ailanthus. Tree-of-heaven is also an invasive species, currently with a very limited distribution in Wisconsin. Learning to identify this tree and removing it from properties are important steps in preventing and managing the spread of spotted lanternfly.
Report potential sightings: Any suspected finds of spotted lanternfly should be immediately reported online to the DATCP spotted lanternfly site. Photos are necessary to verify a report and to confirm identification.
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