Town of Pelham staff have assessed the Town-owned trees in Hillcrest Park through multiple site visits. At this time there is no action being taken, as staff are expecting the trees to recover - reaffirmed by the information provided by NPCA Forester Dan Drennan, R.P.F.
In following these recommendations, staff may consider options for future preventive treatment, in consultation with the NPCA.
Regarding cankerworms on private trees, the Town is not currently planning pest-management efforts on private property. This position is consistent with complaints from residents regarding squirrels, mosquitos, tree seedlings, lady bugs, wasps, etc. on private property. The Town does not perform pest management for individual residences.
The following information is from Dan Drennan, R.P.F, Forester, of the Niagara Peninsula Conservation Authority.
The NPCA has experienced cankerworm infestation on its properties in the Grimsby and Lincoln area. The cankerworm population has crashed there and I expect the same for Pelham. This insect only has one generation per year and the hardwood trees will put on new leaves over the next couple weeks. The insect will not kill the tree on its own. A combination of other factors like drought, age and existing disease will cause mortality. Controlling the population is best done in the spring when they are emerging.
Appearance and Life Cycle
There are two species of cankerworm, spring cankerworm and fall cankerworm. Adult spring cankerworms emerge and deposit eggs in late March and throughout April, whereas fall cankerworm adults emerge and deposit eggs from late September throughout October. Adult males are small-bodied, brownish-grey moths with a 25 mm wing span, whereas females are dark brownish-grey, wingless and 12 mm in length. The larvae of both species emerge in the spring just as the leaves begin to appear and will feed on the foliage until mid-June. Full grown larvae measure 30 mm in length and they range in color from yellowish-green to brownish-green to black. The only means to distinguish cankerworm during the larval stage is to view the false legs at the rear of the caterpillar. Spring cankerworm have two pairs of false legs compared to three pairs on the fall cankerworm. When feeding is complete, the larvae enter the soil where they remain until they emerge as adults, that fall or the following spring depending on the species.
Damage
Cankerworm cause damage by defoliation during the larval stage. Initial feeding causes a shot-hole appearance in the leaves, but advance feeding results in the entire leaf being consumed except for the main veins. Most trees will re-leaf within three weeks after a severe attack. Trees that are defoliated several years in a row will show branch die-back in the crown area.
Control
Landowners with a small number of trees, tree banding is an effective method for controlling cankerworm and gypsy moth. The bands are covered with a layer of sticky adhesive which prevents the wingless females from climbing the trees to lay eggs. For the spring cankerworm, the bands must be in place from mid-March to late April, whereas for the fall cankerworm, the bands should be in place from late September to early November. It’s important to put a barrier such as broad tape or tar paper on the trunk first so that the sticky compound (Tanglefoot™) doesn’t come into direct contract with the bark. Otherwise the Tanglefoot™ will soften or kill the bark. This type of products can be purchased from local hardware/gardening stores or specialized natural insect control stores
While the sticky band will be of benefit in the fall, that still gives time for the caterpillars to defoliate the trees this spring. A biological insecticide known as Bacillus thuringiensis (Btk) can be applied as a foliar spray to kill the caterpillars now to limit the amount of defoliation. Given the early emergence of this insect, Btk applications would need to be done immediately to prevent further defoliation this season.
Chemical control can be achieved by using carbaryl or methoxychlor. The chemical application would not be the ideal option over a broadcast Btk spray as conducted in 2008. The chemical application would require a licensed pesticide applicator and would be ground based. A broadcast chemical spray would unlikely be approved or welcomed by the public.
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