Horticulture

Fall Tree Update

evergreentree.jpegExtension Educator, Kelly Feehan provided some good tips regarding trees which is listed below. The first is a question we usually receive on trees in fall/winter is yellowing of needles on evergreens. Kelly reminds us that this is a natural occurrence and we will soon see natural needle yellowing and dropping on evergreens like white pines and spruce.  This is a process where 2- to 4-year-old interior needles turn yellow, then brown, and eventually drop off.  Needle yellowing occurs throughout the interior of an evergreen from top to bottom.  For tree owners, not familiar with natural needle drop, this sudden yellowing is a concern. However, this is as natural for evergreens as fall coloring is for shade trees. The only difference is it only occurs heavily every 3 to 5 years in evergreens instead of yearly. It is natural and does not harm the tree. Check that only older, inner needles are affected. If needles on branch tips are affected, or needles that are dropping have spots or red bands on them, this could be a sign of a disease and a sample could be brought to the local Extension office for diagnosis and determine if a fungicide application might be needed next spring.

Also, if the leaves of shade trees and shrubs are off-color or have leaf spots, browning, or holes chewed into them; and you’re thinking about applying a pesticide for control, think again. Keep in mind the leaves of shade trees and shrubs will soon be naturally dropping from plants; so, is it necessary to apply a pesticide now to protect leaves that will soon be dead? Tree and shrub leaves have basically done their photosynthesis job for the year. Leaf buds for next year are formed; and photosynthetic products are stored in woody tissue for next year’s growth. Other than aesthetics, minor leaf diseases and insect chewing is not very harmful to trees and shrubs this late in the season; but a pesticide application can kill beneficial insects such as pollinators.  If the damage is unacceptable, or has occurred more than one year in a row, positively identify the cause of damage to help determine if and when control may be needed next season.

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