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Fruit Tree Spraying

Fruit trees such as pear, apple, crabapple, peach, cherry, and plum are breeding grounds for insects and disease. Arborists will tell you that fruit tree spraying is an important part of an integrated fruit tree care program. Here are common conditions and what type of spraying should be applied. 

Target Pest: Worms and Caterpillars
The bane of apple and crabapple trees, you may have had the unpleasant experience of biting into a wormy apple. Worms and caterpillars bore into fruit and foliage for nourishment.

Treatment: Leaves and fruit are sprayed with a general insecticide such as Orthene. When caterpillars or worms feed on the fruit, they ingest a chemical that makes them stop feeding.  

This is a timed, dual spray, applied when buds are visible but still in tight clusters. A second application needs to be applied 10 to 14 days after the first for this to be fully effective. Worms and caterpillars may seem unaffected for several days so be patient.

Target Pest: Peach Borer
This insect will feed under the bark of peach, almond, plum and cherry trees. The adult moth emerges in late spring and again in late summer. The female moth lays her eggs on the bark. When hatched, the larvae bore deep into the bark reaching the crown and damaging the water transfer tissue.

Treatment: The most effective spray is done during the egg and early larval stage. Tengard, a permethrin based products or Sevin, a carbaryl based product more available at garden centers, need to be applied in early summer just as adults lay their eggs.  Borer eggs take 10 days to incubate. A follow up spray may be warranted in later in the summer.

Target Pest: American Plum Borer

An active borer in the decline of cherry orchards in Michigan and New York, the American plum borer typically has two flights, one in mid-May and again in July.  

A plum tree (and any fruit tree for that matter) will be more susceptible if it has any trunk damage, canker or improperly pruned branches oozing sap.

Treatment: An application of Sevin or Safari on the trunk in mid spring with a follow up spray in mid summer.

Target pest: Scale
Scale is a general term for a group of insects well known as a fruit tree pest in the eastern US.  Scale form armor as adults, making them nearly impossible to kill except in their larval stage. Larvae typically emerge in early spring.

Treatment: Dormant oil, a type of horticultural oil, is applied in early spring before the scale emerges. Oil spreads through the bark and coats dormant insects, effectively smothering them to death. Since dormant oil blocks spiracles (air holes), entire colonies within the tree can die of suffocation.

Target Pest: Mites
Mites overwinter within a tree as eggs but won’t emerge until the next summer, as  temperatures rise. Healthier apples trees and Bradford pear will tolerate mite activity, but if your ornamental is targeted by mites, it can quickly defoliate your tree.

Treatment: Dormant oils will trap and suffocate mite eggs before they emerge. A mid summer general insect spray mixed with a miticide offers late season control.

About the Author

David Merriman is an ISA arborist and owner of ArborScape, a Denver tree service.

David sees his occupation as more of a passion then a job. Read more tree care articles at http://www.arborscapeservices.com/articles

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