Spruce Budworm has arrived - March 7, 2015

Posted on March 07 2015

Spruce budworm has arrived in New Brunswick.

In recent years the New Brunswick Department of Natural Resources in coordination with several local forestry groups (University of New Brunswick; Government of New Brunswick; Natural Resources Canada; Twin Rivers; Fornebu Lumber; J.D. Irving, Limited; AV Group; Acadian Timber; Forest Protection Limited) has intensified regional surveys for budworm, using a combination of both pheromone traps (to monitor adults) and branch sampling to determine densities of hibernating larvae (aka “L2 larvae”). Sampling for hibernating larvae involves snipping three branch tips (about 75 cm) in a plot (Picture 1) and then ‘washing’ these branches back in the laboratory with a chemical that separates the larvae from the branch so that they may be counted (Picture 2). The budworm density estimates these samples provide are considered to be a strong indicator of the local population density and can help us predict how much defoliation to expect in the following year.

In 2014, the province sampled 1349 plots throughout New Brunswick (Picture 3). Through these surveys the province discovered some unusually high budworm densities in the spruce-fir forests south of Campbellton. At least six plots within a ~15,000 hectare area, just south of the city, had as many as 10-12 larvae per branch (Picture 4). Of course, these budworm levels are still far below those observed during the 1980`s, when some branches could occasionally yield as many as 200+ larvae; however, 10 or more larvae per branch is far above anything seen in New Brunswick since the previous outbreak, and is sufficient to cause noticeable defoliation.   

From the perspective of our ongoing research project, this apparent ‘hot spot’ provides an ideal opportunity to test the Early Intervention Strategy, whereby small pockets of spruce budworm are targeted to prevent the local outbreak from rising. However, more surveys are needed to better understand the shape and contours of the spruce budworm population in the area. As such, during the months of January and February, our research group braved the cold on snowshoes and snowmobiles to collect additional survey branches in the area aiming to both confirm and map out the forest stands most affected by budworm.

We will be periodically updating the blog to provide further details on the results of these surveys and our plans for 2015.

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