I believe my euonymus shrub has euonymus scale. How do I treat this organically, if possible?

Gardens & Landscapes September 05, 2011 Print Friendly and PDF

You may want to read the following Cooperative Extension fact sheet (EntFact 428) from the University of Kentucky: Euonymus Scale. The following information on organic control was excerpted from the fact sheet: Cultural Control:  Scales tend to thrive on stressed plants. Following a recommended fertility program and watering regime will promote plant health. However, overfertilization favors scale buildup. If practical, improve plant sites to reduce stress and promote growth. Severely prune back heavily infested branches, and protect new growth with insecticide applications. • Insecticidal Sprays:  Horticultural oils kill by suffocation or after-penetrating overwintering stages of the insect. Consequently, they may not be effective where several layers of scale coverings have accumulated. Dormant oils are typically applied during February or March, but may not be very effective against armored scales. Highly refined supreme, superior, or summer oils can be used on many trees and shrubs during the growing season. Read the product label for guidelines on plant sensitivity and temperature restriction before buying and using these products. Insecticidal soaps are long-chain fatty acids that kill susceptible insects through direct contact. Like horticultural oils, these soaps require thorough coverage. Soaps leave no residue, so repeated applications may be needed for some pests. These products may burn the foliage of sensitive plants, such as Japanese maple, so check the label for information about the plant species you intend to treat. A variety of natural and synthetic insecticides are labeled for use as sprays to control scale crawlers on landscape trees and shrubs. While the residual life of these products is generally longer than oils and soaps, timing, coverage, and precautions on damage to some plant species are very similar to those for oils and soaps. When using pesticides, organic or not, read the entire label and follow the label instructions for use.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.