Lawn Herbicide and Trees

Watch for Possible Broadleaf Lawn Herbicide Injury to Trees
Damage to trees due to broadleaf lawn herbicides is a rare event; but when it does occur, it can create a lot of anxiety and customer dissatisfaction. This year, damage has been observed on certain tree species (primarily Norway spruce and white pine) following spring applications of a new herbicide called Imprelis. Pete Landschoot, Professor of Turfgrass Science, recently provided an update on this situation. Here’s a brief summary of his report.

Effects on trees:
First, not all applications of Imprelis result in tree injury. The recently observed injury seems to be related to the soaking spring rains we experienced in April and May. We are not aware of any tree injury following fall applications.

In cases where injury did occur, symptoms to Norway spruce began as yellowing, curling, and browning of the current season’s growth. In some cases, injury does not progress much further than slight curling and browning of new growth; however, in other cases complete dieback is observed. In severe cases, the entire tree turns brown and begins to lose its needles. Trees of all ages have been affected to varying degrees. White pine injury appears as severe twisting and curling followed by needle drop of the new season’s growth. Because of the spiral pattern of the vascular system in many conifers, damage from herbicide uptake may even appear as a spiral on foliage.

What can be done about injured trees?
Since a number of factors can cause symptoms similar to Imprelis injury it’s important to make sure tree injury is a result of herbicide uptake. Call a qualified arborist or bring in samples to your local Penn State Extension office.

In cases where injury is clearly herbicide induced, do not fertilize trees for at least one growing season (excess growth can compound injury). If drought begins to set in, watering to alleviate stress may be useful on trees that received slight to moderate damage. Place a soaker hose on the soil near the trunk of injured Norway spruce trees that have low hanging branches. This allows slow irrigation of the soil directly under the tree, and reduces the risk of additional active ingredient being taken up by the tree. On trees with dieback, pruning should be delayed for up to a year to fully assess the extent of the damage, and to allow for recovery.

Penn State Cooperative Extension will provide updates as more information becomes available. To find the latest updates go to http://extension.psu.edu/ and search on the term Imprelis.

To read Dr. Landschoot’s full article go to http://extension.psu.edu/greenindustry/giec/news/2011/some-observations-on-imprelis-injury-to-trees Or contact your local cooperative extension office. In Lackawanna County ask for the Garden Help line at 963-6842 or email LackawannaMG@psu.edu


Terry Schettini, Extension Educator
Penn State Cooperative Extension in Lackawanna County

Choosing a Christmas Tree

Do you need some guidance in choosing a Christmas tree? Trying to decide artificial or real? As another holiday season approaches, here are some considerations to guide you:

In general, artificial trees are easier to manage and are less messy than real ones. They are also hypoallergenic. Artificial trees can be used for many years to come, spreading their cost out. They never need watering either. However, as they become worn, damaged or outdated, they end up in landfills. They will spend centuries of holiday seasons buried, taking up valuable space.

Choosing a real Christmas tree is important for Pennsylvania. There are about 2,000 Christmas tree farms in the state, adding to the local economies. These farms cover 35,000 acres producing 1.2 million cut trees each year. Almost fourteen million dollars in sales are generated by PA Christmas tree farms.

These farms also stabilize the environment. The land itself is productive, preserving habitats lost in development. Plus soil erosion is reduced and trees are great air purifiers and give off oxygen. Tree farms help abate soil erosion, storm water runoff, and add aesthetically to the areas around the farm.

Ready to shop for a real tree? There are many varieties of trees from which you can choose. Seventy percent of PA Christmas trees are Douglas fir and Fraser fir. The Fraser fir is usually the top choice due its fragrance and needle retention.

• Balsam Fir: soft, dark green foliage, with flattened needles about three-quarters of an inch in length, has a distinctive “balsam” aroma, excellent needle retention.
• Colorado Blue Spruce: stout, three-sided needles about three-quarters of an inch in length. Its foliage can vary in color from dark green to indigo blue. Its sturdy branching and good needle retention make it a desirable Christmas tree, while its excellent form and outstanding color make it the premier ornamental evergreen.
• Douglas Fir: widely used as a Christmas tree in the Northeast. Its lush, blue-green foliage, with needles about one inch in length, and outstanding needle retention make this a holiday favorite.
• Scotch Pine: one of the first farm-grown Christmas trees in the United States. Its sharp, blue-green foliage, with needles about two to three inches in length. It conical shape, excellent color, and needle retention made it the Christmas tree of choice for many years.
• White Pine: native to the Northeast, has soft, lacy, blue-green foliage with needles about three to four inches in length. A very graceful-looking evergreen, it fragrance and excellent needle retention made it a popular Christmas tree.
• Fraser Fir: closely related to Douglas Fir. Its soft, emerald-green needles with silvery undersides are about three-quarters of an inch in length. Its bottlebrush texture, sturdy branching, and outstanding needle retention make it a superb Christmas tree whose popularity has grown rapidly in recent years.

Just as importantly, care is crucial for you to get the most out of your selection. For more information on Christmas tree selection, please contact the Penn State Master Gardeners in Lackawanna County at 570 963-6842 or email: LackawannaMG@psu.edu and ask for the publication “Caring for Your Cut Christmas Tree”.

Steve Ward
Master Gardener Coordinator
Lackawanna County