Tag Archives: Spruce

April 12, 2018

Gypsy Moth Caterpillars -Scout for them now

We often don’t think of gypsy moths as damaging conifers but it can be a big problem!  Left unchecked young trees can be killed in a single season.

 

Spruce trees killed by gypsy moth defoliation in the 2017 growing season – Upstate NY.

Scouting for egg masses in nurseries and Christmas tree plantings is important from autumn to early spring before the eggs hatch into tiny caterpillars.     It’s not too late! Stick your head in the trees and look at the trunks to see if there any tan-white egg masses.

Gypsy moth egg mass on trunk.

Egg mass removed from tree.

Egg mass broken up to reveal individual eggs.

 

Recently hatched caterpillars on the egg mass.

Normally the caterpillars begin to hatch outdoors sometime in early May.

Young caterpillars on the move!  These hatched  from an egg mass that was left in the lab for several days at room temperature.

Close up of a  juvenile gypsy moth caterpillar.

The young caterpillars are the most susceptible and easiest to control compared to caterpillars that have grown larger.
For more information see the Cornell Insect Diagnostic Laboratory factsheet on gypsy moths.

July 8, 2013

White Pine Weevil

Dieback due to white pine weevil larva feeding.

Noticing a wilted leader on pines or spruces?  White pine weevil is likely the culprit. Although it’s almost officially summer when the symptoms are first noticed it all started back in the early spring when, on a warm day in March- April, the female weevil lays her tiny eggs a few inches below the terminal bud. Those eggs soon hatch and the young larvae start to consume the stem’s vascular tissue.    With the loss of this vascular pipework the tree’s terminal leader wilts and brown dieback soon becomes visible.

With the bark peeled back, a white pine weevil larva is visible inside spruce leader.

In late July and August adult weevils emerge through small holes they carved at the base of the dead terminal.  After the adult weevils emerge they enter leaf liter and are not seen until March of the following year.  If you prune out and destroy the affected leaders before the holes appear and the adults emerge (Late June to mid-July for most of New York) you can reduce numbers of adults that will lay next year’s eggs.

Exit holes of at base of area damaged by White Pine Weevils. Prune and destroy before these are visible.

A blue spruce disfigured due to a missing leader caused by White Pine Weevil damage.

White pine weevil is one of the earliest pests we treat for in the spring.  Knowing when to treat can be tricky.  Using growing degree days in the spring can be helpful to prevent damage.  

See the Insect Section of Pest Management Guide for Commercial Production and Maintenance of Trees and Shrubs for growing degree day target window for treatment  and other control information.