Many woodland owners and others around the state noticed a recent browning of white pines, followed by needle drop reminiscent of autumn. As one observer said, “Golden needles are falling like snow!” The July 1 WoodsWiseWire included a segment outlining the problem known as White Pine needle cast disease. Recent rains have brought down most if not all the affected needles, leaving some crowns green but a little thin looking, and leaving many to wonder if Maine’s white pine trees are in danger.

Growing Eastern white pine is generally a rewarding activity both ecologically and economically.  Eastern white pine is one of the faster-growing and most valuable native conifers in Maine and, for this reason, offers a great opportunity to observe forest growth and developmental changes over a relatively short period of time.  But as with all living things, white pine is susceptible to a variety of pest problems, including both insects and diseases. Woodlot owners and managers growing white pine should become familiar with these principal pests so that if problems arise, the problem can be identified quickly, and timely management actions can be taken. Besides the needle cast, other diseases such as white pine blister rust and Caliciopsis Canker may be present. Insects that commonly cause problems for white pine include the white pine weevil, the pine leaf adelgid, and the red turpentine beetle.

It’s very important to remember that no one of these pests is an automatic killer of pine trees. Rather, they all add stress to the viability of infested trees, each in their own way. For instance, the needle cast reduces the amount of live crown, thereby reducing the ability of a tree to perform photosynthesis and store sugar (energy) for future growth, seed production and defense from other pests.

Besides insects and disease, other sources of stress on pine (and all trees really) include site (too wet, too dry, not enough room for roots to grow); weather (prolonged drought is probably the worst case); or mechanical damage from snow plows, logging equipment, and the like. It’s usually an accumulation of problems that weakens trees over time, until one last factor (perhaps red turpentine beetles) delivers the final blow to a given tree.

While all this may seem depressing to a woodland owner, keep in mind that most of our forests have a healthy mixture of species and sites, and a range of individual tree health and vigor. It is very unlikely that an entire stand or woodlot will be devastated all at once. Keeping an eye on your woods, seeking professional advice, and planning and carrying out practices such as thinning, weeding, and (when needed) regeneration cutting.  These practices will greatly reduce the chance of any one pest becoming a major problem. Active stewardship will help you reach your goals and objectives for your land.

To find out more, check out MFS information Sheet # 24, Principal Disease and Insect Pests of White Pine in Maine.

As always, you can call the Maine Forest Service for more information or assistance at 1 800 367-0223 (in state) or (207) 287-2791, or e-mail forestinfo@maine.gov