Damage from previously active White Pine Weevil larvae (Pissodes strobi) has been evident for the past several weeks on Eastern white pine, Norway spruce, Siberian spruce, Colorado blue spruce, & Douglas-fir. The larvae began feeding within the terminal leaders last April. When the terminal leader is heavily infested, larvae feed side by side in a ring encircling the stem. By late spring or early summer, most White Pine Weevil larvae have pupated & emerged as adults. The terminal leader has become stunted and wilted. It is too late in the season to save the leader and it should be pruned out. To re-establish a new leader and retain the desirable Christmas tree shape read further & follow the procedures suggested.

The 2014 leader & laterals of this Eastern white pine were killed by White Pine Weevils this past spring. Photo Credit: Steven K. Rettke of RCE

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The announcement that the invasive pest Emerald Ash Borer (EAB) is present in NJ will lead to many discussions between professionals and concerned clients on what to do about their ash trees. EAB represents a broad threat – it attacks all true ash (Fraxinus) species. In the U.S., trees die within a few years without treatment. Research out of Ohio by Dan Herms points to the need for long term control efforts – possibly 15 to 20 years. Feasibility of treatment on an individual basis balances the cost of effective treatment vs the cost of removal of trees killed by EAB – which is not small.

Landscape Options for EAB

Confusion arises when discussing management of ash tree populations (forest or landscape) at risk due to EAB. Any discussion involving treatment does not apply to whole forests because methods and treatment costs make that impossible. Specific options available to landscaped areas include: elimination, preservation, and conservation.

June 2006 Urban Ash Trees Pre-EAB	August 2009 Urban Ash Trees Post-EAB
Photos by D. Herms, Ohio State University

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Black Vine Weevil Adults Are Noctural and Cause Feeding Damage at Night. Proto Credit: Steven K. Rettke of RCE

Many landscape & nursery managers consistently state that attempting to manage the black vine weevil insect (Otiorhynchus subcatus) as one of the most problematic pests they encounter. These leaf notching weevils feed on many kinds of ornamental plants including yews, rhododendrons, azaleas, laurels, leucothoe, forsythia, euonymus, hollies, viburnum, most deciduous and evergreen shrubs, ground covers and many kinds of perennials and annuals.

Controlling Black Vine Weevil adults during the month of June will prevent egg laying during the weeks of July. This beetle only has one generation a year.

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