Historical Forest Health News – 1993 and 1968

News from 25 years ago (1993)

Jack pine budworm Choristoneura pinus (Rohwer)

Area of defoliation by jack pine budworm in 1993 shaded in black.

Area of defoliation by jack pine budworm in 1993 shaded in black.

“This defoliator erupted in northern and central Wisconsin to cause moderate to heavy defoliation on 400,000 acres of jack pine. This was the second year of defoliation in Clark, Eau Claire and Jackson counties, and first year defoliation in Monroe County. The largest areas of defoliation were in the northwest where periodic outbreaks are expected. Heavy defoliation occurred in Adams, Juneau, Wood, Clark, Eau Claire, Jackson and Monroe counties. Light feeding was apparent in the Conover area of Vilas county. In Oconto county a 90-acre planting of sapling white pine suffered heavy terminal and upper lateral defoliation. Spotty light to moderate defoliation occurred in Oconto and Marinette counties in the northeast. Defoliation in Marinette county was heaviest in over-mature natural stands of jack pine stands in Silver Cliff Township (Sections 22, 23, 27, 26, 34, 35, T34N, RISE).

In Juneau and Wood counties, tree mortality is expected to be high because many trees lost 90 to 100 percent of their foliage. Salvage harvests were scheduled in the defoliated stands that were predicted to suffer heavy mortality. Some of the harvests in the central and westcentral counties were in potential conflict with the protection of the Karner blue butterfly, a newly listed endangered species. Guidelines were developed to survey for the Karner Blue and for its food plant, blue lupine. The guidelines also contain procedures to prevent damage to known Karner Blue habitat during harvest operations. Many defoliated stands that were scheduled for salvage harvests were surveyed. Late season egg mass surveys revealed a 33% decline from 1992 levels in the northwestern counties portending a decrease in populations and defoliation in 1994. In western and central Wisconsin, the egg mass surveys indicate the budworm populations should remain high in 1994. Egg mass surveys in Wood County averaged 5.8 egg masses per plot. Egg mass surveys in Marinette county indicate defoliation will likely be spotty and variable in intensity again in 1994.”


“Heavy rain from May to July caused flooding of many stands of red and jack pine in central Wisconsin. Many trees were killed during the summer; others were very yellow and will probably die. In some areas the plantations were still under six inches of water in December. In Juneau County, a 20-acre sapling red and jack pine plantation was under 6 inches of water from May through August. Many trees were yellow, and many were dead by October. In Adams County, several scattered natural jack pine stands and red pine plantations were under water for two months. Mortality was heavy east of Highway 13 and south of Rome to Big Flats; the pine engraver was present in the dead trees.”


News from 50 years ago (1968)

Pink-striped oak wormAnisota virginiensis (Drury)

“The first known extensive defoliation by this insect in Wisconsin occurred near Bardon and other lakes west of Gordon in Douglas County during the summer of 1968. Approximately 400 acres of scrub northern pin oak were completely defoliated in an area that covered parts of Sections 15, 16, 21 and 22, T43N, R12W. The stand of oak was of no commercial value, but likely of high esthetic value to the owners of lakeshore cabins in the midst of the infestation. Larvae were near mature and very numerous in the leafless trees and on the ground when the area was visited on July 31. Many of the larvae perished from starvation and other causes before they completed their development.”

Jack pine budworm – Choristoneura pinus (Freeman):    

Northwest Area

  • “Severe defoliation of Northwest area jack pine stands in 1967 left few suitable feeding sites for young larvae and resulted in lower early instar larval counts in 1968. Second instar larvae left hibernacula about mid-May but persistent cold, cloudy, wet weather impeded their feeding. Later larval development was also slow and erratic as similar weather continued throughout the growing season.
  • Parasites were abundant in most infested jack pine stands in the northwest counties, with Apanteles wasps taking the greatest toll of budworm larvae. Late-instar larval counts were down throughout the Northwest Area and only a few isolated stands showed noticeable browning due to budworm feeding. Further evidence of the budworm population decline to endemic levels were low pupal and egg-mass counts over the entire area.
  • Tree mortality, principally due to bark beetle attacks on top-killed trees, continued in stands severely defoliated in 1967.
  • Many severely defoliated stands in Burnett, Douglas and Bayfield Counties were assigned high cutting priorities and harvested. Unfavorable market conditions temporarily hindered some landowners in the removal of budworm-defoliated jack pine from afflicted areas, but pessimism was displaced by optimism as marketability of timber improved toward the end of 1968.”

Northeast area

  • “Defoliation ranging in intensity from light to heavy occurred on 19,900 acres of jack pine timber in the Northeast Area. Acreage affected, by counties, was as follows:
    County Acreage
     Oconto 1,200
     Oneida 2,800
     Vilas
                  Boulder Junction 2,800
                  Conover vicinity 6,700
    Marinette 6,400
    Total 19,900 acres
  • Severe defoliation occurred for the first time in recent years (since 1956-57) near Lake Nokomis and Hazelhurst in Oneida County; in the vicinity of Thunder Lake and Caldron Falls in Marinette County; and near Stormy Lake and Lac Vieux Desert in Vilas County. Severe defoliation was apparent in stands near Boulder Junction for the second consecutive year, and near Conover for the third year. The last two communities named are in western and east central Vilas County respectively. Defoliation was generally most severe on large mature trees, and jack pine timber on a 120-acre area near Conover that was defoliated in 1967, was killed. High mortality also occurred in a younger adjacent plantation. Top-killing is anticipated in stands most heavily defoliated. 
  • Much of the damaged jack pine on state and county lands has been cut, and routine timber sales are expected to provide for orderly removal and utilization of remaining damaged trees.”

West Central area

  • “Budworm populations were higher during 1968 than previous years in jack pine stands in Adams, Jackson, Juneau, Monroe, and Wood Counties. Heavy defoliation occurred on approximately 3,000 acres in Juneau County. Light to medium defoliation (light browning and thinned foliage) occurred on 5,000 to 6,000 additional acres in Juneau County; 1,000 to 1,500 acres in Adams County; 4,000 acres in Jackson County; and 1,500 to 2,000 acres in Wood County. Total light defoliation in the West Central Area is estimated at 12,000 to 13,000 acres. 
  • Some top killing and loss of reproduction may occur in the area of heavy defoliation, but good moisture conditions and the young, vigorous condition of the stands are expected to keep tree loss to a minimum.
  • Egg surveys indicated lower budworm populations will occur in most of the infested areas in 1969, but medium defoliation may be expected in parts of four additional townships in southeast Wood County and northern Adams County. No apparent budworm defoliation occurred in jack pine stands in other areas.”

Phenological notes:

  • May 13 – Budworm larvae out of hibernation in Burnett and Washburn Counties. Jack pine leaders 3″ to 6″ long, pollen flowers large and yellow-green.
  • May 14 – Budworm larvae out of hibernation in Douglas and Bayfield Counties. Jack pine leaders 1″ to 1 ½” long on young trees, pollen flowers green and hard.
  • May 16 – Jack pine shoots 1” long and no 2nd instar larvae found in Vilas County trees examined.
  • May 22 – Larvae still small 2nd instar in Washburn and Burnett Counties. Jack pine leaders 3″ to 10″ long. Pollen ripe and mostly disseminated. Third instar larvae in Adams, Jackson and Juneau Counties.
  • June 3 – Larvae still small 2nd instar in Douglas and Bayfield Counties. Jack pine leaders 3″ to 6” long and pollen ripe, being shed.
  • June 5 – Larvae starting to feed in western Douglas County. Some 3rd instar larvae found. Pollen gone.
  • June 6 – Jack pine terminals 1” to 4″ long. Budworm larvae 80% in 2nd instar and 20% in the 3rd. Third instar larvae were feeding in staminate flowers in Vilas County. Most larvae in the 4th and a few in the 5th instar in Juneau County.
  • June 11 – Budworm larvae mostly in the 3rd instar and a few in the 4th in staminate flowers in Vilas County. Thirty per cent in 4th instar, 50% in 5th and 20% in 6th in star in Jackson County.
  • June 12 – Twenty percent in 4th instar, 50% in 5th and 30% in 6th and 2 pupae in Adams, Wood and Juneau Counties.
  • June 13 – Larvae ranged from 2nd through 4th instars in Sawyer and eastern Washburn Counties.
  • June 17 – First pupae on Scotch pine in Adams County; about 60% in 5th instar, rest in 4th and 6th instars.
  • June 18 – Larvae in 3rd, 4th, and 5th instars in Washburn County. First Apanteles cocoon found for the season.
  • June 20 Larvae pupating in Jackson County.
  • July 1 First pupae of the season observed in Douglas County.
  • July 2 – Most larvae in the late 4th or early 5th instars, feeding on old needles in Vilas County.
  • July 7 – About 17% of larvae pupated in Vilas County.
  • July 10 – Thirty per cent of larvae pupated in western Douglas County and about 50% in Washburn County.
  • July 11 – About 10% of larvae had pupated in western Douglas and Bayfield Counties. Moths had emerged from most pupae observed near Necedah (Juneau County) and most eggs had hatched in one egg mass. 
  • July 16 – Pupation completed in Polk and Burnett Counties and some moths emerged.
  • July 24 – Budworm moth emergence complete in Douglas County.
  • August 2-6 – Moths were numerous in Douglas County. Relatively few egg masses found, some still green, most masses hatched.”
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