Current Conditions
The past couple of weeks the weather has been a variable grab bag of weather extremes. While May ended dry and cool, much of the region experienced higher than normal seasonal temperatures and humidity over the past week. Daytime highs have ranged from the dry 50s along the coast to the 80s with 90% humidity inland. There has been a mix of sunny, overcast and partially sunny days with little in the way of precipitation accumulation. The region averaged only about 0.65 inches of rainfall, significantly shy of the seasonal norm. Lawns are still thriving and green, although weeds such as clover, aster and vetch are also popping up. In many places rhododendrons and azaleas continue blooming spectacularly, while multiflora rose, peonies, red twig dogwoods, many viburnums, weigela, honeysuckle, lupines, phlox, black cherries and black locust have all been flowering. On average 331 growing degree days have been added so far this season, and the soil temperatures have reached an average of 63 degrees. Of course as the growing season continues so do the potential pest problems, mosquito and tick populations are burgeoning and very active. While wintermoth caterpillars have stopped feeding and pupated, fall cankerworm, forest tent caterpillar, azalea sawfly, european pine sawfly, roseslug sawfly, lily leaf beetle, spruce spidermites and lacebugs remain active while a few new pests arrive on the scene.
Contemporary Concerns
As the season progresses, weather changes and plants continue to grow so do pest populations. Discussed below are some current pests of concern, now being sighted and reported around the region. Mosquitoes and ticks continue to be of great concern, as vectors of disease you need to remember to always take measures to protect yourself from these pests. Contact your arborist regarding additional treatments to safeguard yourself, your property, your family and pests from ticks and mosquitoes.
Larvae of the viburnum leaf beetle and fallen to the soil for pupation, adults, like the one pictured here, will begin to appear in July. The adults will continue to feed on larval host plants and are able to completely defoliate these plants.
Mountain ash sawfly can be a serious problem, females lay eggs in marginal points of serrated-leaf bearing plants. Egg sites will turn into brown, necrotic patches and larvae emerge and immediately begin consuming surrounding foliage, leaving only a midrib uneaten.
The mustard sallow caterpillar is out and active. They prefer witchazel plants and cultivars thereof, populations are capable of near complete defoliation.
There are many species of fruitworm caterpillar, but green fruitworm, as pictured here, is very common. They feed on a wide variety of deciduous host plants. These pale green caterpillars bearing white stripes resembles wintermoth caterpillars but they are much larger and have more prolegs. Fruitworm caterpillars can be found feeding on crabapples, apple, blueberry, oaks, maples and deciduous azalea among others plants.
Euonymus caterpillars are yellow with black spots and produce copious amounts of silk which they use to move throughout the plant. Upon pupation the euonymus caterpillar spins a silken cocoon which ends up resembling a furry grain of rice, control becomes difficult at this point.
Treatments need to occur at the times when they will be most effective, of course, sometimes the weather prohibits the ability or effectiveness of products. Your arborist and plant healthcare technician will schedule applications and monitoring as suited to your landscape’s needs, expected leaf out, insect life cycles and ideal weather. Because weather patterns are not one hundred percent predictable and pest problems are not an exact science, plant healthcare has to be flexible and adaptive, be assured they are doing their very best to get and maintain the optimal results for your landscape.
