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Aphids Causing a Sticky Situation

Post Date:09/01/2017 4:03 PM
AphidleaveThere are several neighborhoods around town that have the Modesto Ash planted in the parkways. They were the theme tree of choice back when the tracts were established 50-60 + years ago, in fact, it is the second most numerus street tree species in San Luis Obispo. Currently many of these trees  are being fed on by Woolly aphids, feasting on the tree’s sugar supply, causing a sticky residue to cover everything under their canopies. 

The City’s Urban Forestry team has found that one way to help reduce aphids on infested trees is to squirt them with a garden hose using a concentrated spray to wash them off the leaves, disrupting their lifecycle. The University of California’s Integrated Pest Management Program has also found that highly selective use of commonly available insecticides around the trunk of the tree about knee high in a concentrated band will discourage ants that are attracted to the sugar drip produced by the aphids feeding. The ants protect the aphids from predators. Predator insects can keep the sucking aphids in check if the ants are not able to enter the top and fight the predators off. This will further reduce the pest numbers as well. Repeat these procedures every two weeks until the problem subsides. Remember, this treatment will reduce the pest levels but not eliminate them. As fall approaches this problem will subside. Additional information can be found on the website for the University of California’s Integrated Pest Management Program.