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We have gotten a number of inquiries from residents about areas where trees
have lost their leaves, including here at Warren County Municipal Center.
What's going on?


Unfortunately, it's turning into a bad spring for leaf-eating caterpillars, and they
are wreaking havoc on trees around Lake George, along the Northway and on
mountainsides in different parts of the county.


Warren County has created a reporting website to document areas of concern,
to be passed along to agencies that could respond.
Find it here:


We talked to Jim Lieberum, district manager for Warren County Soil and Water Conservation District, whose office is also fielding calls about it, and here is what he had to say:


"To my knowledge at this time, there is not any approach that can be done to effectively treat the outbreak that we are experiencing. Since their introduction into the United States, different parts of primarily the eastern US experience outbreaks ever few years. There is a bacterium in the soil Bacillus thuringiensis (also know as BT), that when activated will quickly destroy the caterpillars. 


If we have a dry year then it will not work as well and we will likely have more damage than we would want. If the recent rains activate the bacterium then hopefully it will begin the process of killing off the caterpillars. It does appear that landowners can apply BT to leaves of trees and it is an effective treatment if the timing and application rates are correct.


What research has shown is that trees should re-leaf in July after the caterpillars have going through their cycle.  There will be trees that do not make it and I would suspect those were already stressed in some way. 


If a landowner was concerned about some yard trees and/or new plantings, I would place a special insect tape (or search for other tape-inverted duct tape works from what I read) around the tree to capture the caterpillars as they go up the trunk, water trees that are defoliating and possibly using some natural type of fertilizer or compost to provide additional nutrients to the tree.    


While these caterpillars create unsightly trees and kill some newly planted stock and other
stressed trees, gypsy moths are one of the lesser invasive insects that we are experiencing. 


An example of this is the Emerald Ash Borer, of which there is no effective treatment and
the ash trees will be killed in 1-2 years. Problems will occur if we see this gypsy moth issue
for several years in a row and if we have hot, dry years.


We also suggest that you go to this Cornell Cooperative Extension’s link - or reach out to the Capital Region PRISM ( PARTNERSHIP FOR REGIONAL INVASIVE SPECIES MANAGEMENT), as they are dealing with numerous calls and questions daily and have several terrestrial invasive species folks on staff."

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