Q • I noticed my pine tree starting to turn yellow on the inside and dropping a lot of needles. I’m worried it has some kind of disease.
A • Any time you think you have a disease it is a good idea to check for any irregular spots or discoloration. If your needles are turning an even yellow shade, starting from the inside of the tree without any blemishes, this is probably seasonal needle drop and there is no need for concern.
Evergreens don’t have the same striking leaf drop as deciduous species in the fall, but they do drop their old needles as they grow. Many species slowly shed needles as they grow, but pines, especially white pines, have a flair for the dramatic. White pines will hold their needles for two to three years, then drop all but the current year’s growth in the fall.
If you notice any irregularities, needles dropping outside of fall, or it just helps ease concerns, you can contact MU’s Plant Diagnostic Clinic to process a sample and verify any diseases for about $15: extension.missouri.edu/programs/plant-diagnostic-clinic.
Write to the Missouri Botanical Garden's Center for Home Gardening at email@example.com or the Horticulture Answer Service, 4344 Shaw Blvd., St. Louis, MO 63110.