White Pine Weevil

White pine weevil, Pissodes strobi, is considered the most destructive insect pest of Eastern white pine in North America.  This insect kills the terminal leader (primarily of Eastern white pine), causing significant damage.  Infested trees often have a deformed top, leaving them prone to storm damage and stem failure.  White pine weevils prefer Eastern white pine and various spruces that are exposed to direct sunlight.

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White Pine Weevil Treatment Option 1

Soil applied systemic insecticides, such as Xytect™, work very well for the protection of valuable trees.  These products are poured on the soil at the base of the tree and work from the inside of the tree to control feeding larvae.  Applications are best timed in the fall to control next year’s larvae, since Xytect™ takes up to a month to reach the top of large trees.  Xytect™ lasts for one year in the tree, so annual treatments are recommended to maintain protection, especially for trees growing in full sunlight.

Application Type Soil drench

DIY Product/Equipment Needed:

• Xytect

• Soil Drench Kit

• Measuring or diameter tape

• Bucket or watering can

• Gloves

White Pine Weevil Treatment Option 2

Sprays of Up Star® Gold need to be completed either in the spring as adults are emerging from the soil, or in the fall after new adults emerge. However, perfect timing can be a challenge because most of the weevil’s life cycle occurs inside the tree.  Applications should be concentrated to the leader and upper branches to control adults as they are feeding.

Application Type Foliar spray

DIY Product/Equipment Needed:

• Up-Star Gold

• Hand pump sprayer with wand

• Gloves

• Safety glasses

White Pine Weevil DIY Kit

Option 1

Application Type Soil drench

DIY Product/Equipment Needed:

• Xytect

• Soil Drench Kit

• Measuring or diameter tape

• Bucket or watering can

• Gloves

Option 2

Application Type Foliar spray

DIY Product/Equipment Needed:

• Up-Star Gold

• Hand pump sprayer with wand

• Gloves

• Safety glasses

How Is It Spread?

Biology

Adult white pine weevils overwinter in the leaf litter underneath trees.  They emerge from this protection from mid-March through mid-April.  Adult females climb trees to feed on leaders and lay 1-5 eggs in the wounds they create.  Eggs hatch a week later as larvae, which mature and pupate in mid-July in spaces carved into the sapwood.  Adult white pine weevils emerge from pupation in late July and August and briefly feed on the upper tree branches before moving to the ground to overwinter.

Susceptible Trees

In theUnited States, white pine weevils may attack at least 20 tree species; however, they prefer Eastern white pine, jack pine, and Norway spruce.

Symptoms

  • The first evidence of white pine weevils is tiny glistening drops of resin exuding from punctures just below the terminal bud.
  • Wilted new shoots with reddish-brown needles.
  • Shepherd’s crook pattern to the terminal leader.
  • Repeated damage to terminal leader often causes a deformed or forked top.

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