Scale control on seedling flats

Asked November 15, 2018, 11:10 AM EST

Good Morning. My question pertains to type and timing of scale control chemicals to be used on my seedling flats that I will be bringing into my home for the winter. These flats contain exotic species of conifer trees (cedrus, pinus, and abies) and number less than 100 seedlings less than 12" high. They have been outside since early spring. The problem is the presence of scales on a number of my cedrus libani trees. They are brown, oval/oblong, approximately 1/16" long, and are found on the stem and leaves. I have tried manually scraping them off, but with wearing trifocals this becomes tiring. Plus I obviously miss some. Whatever I apply will obviously be a small amount, but the question is: what to apply and when? Choices being a systemic insecticide (what) or insecticidal soap; and before bringing them into my growing area, just after they've warmed up and acclimated, or wait till bud swelling/burst. Thank you.

Anoka County Minnesota

1 Response

Your somewhat specialized question is beyond the expertise of most master gardeners. However, information at this website may be useful:

If you need more help, please direct your question to

Steven Frank
Professor and Extension Specialist Entomology & Plant Pathology
FAX:(919) 515-7746