Fielding Questions: Tree holes? Chances are, it’s nature’s carpenters wreaking havoc (2024)

Q: I’m not sure if the tree in our backyard has a disease. Can you help? — Bob W.

A: Thanks for sending the photo. The tree has been attacked by sapsucker woodpeckers, and based on the number of questions I’m receiving, this is a widespread problem.

Contributed

The sapsuckers create holes in the tree’s trunk, allow them to fill with sap, and then drink the liquid. The birds often go unnoticed, working in early hours, which is why they’re not often caught in the act.

The holes are usually created in rows, drilling into the tree’s sap-conducting tissue, although some holes are randomized. If the holes are frequent enough, and extend far enough around the trunk’s circumference, the tree can be damaged, as the holes disrupt the necessary flow of sap within the tree.

Keeping birds out of trees is a perpetual challenge. Sapsuckers usually begin working in a localized area of the trunk. If caught early enough, the area can be wrapped with burlap or aluminum foil, which can frighten the bird to leave the tree.

If a larger area is already affected, wrapping can still help, but it will be more difficult. Scare tactics — such as hanging Mylar balloons, reflective tape streamers, pie tins or old CDs in the tree — can be tried.

A product sold at garden centers and hardware stores for repelling birds is a sticky product made by the Tanglefoot company. The gooey material is applied to the trunk of the tree in the area of sapsucker activity, and birds will hesitate to land in the sticky zone.

There are no pruning paints or sealers that should be applied to the area of damage that can help the tree heal. The tree needs to self-heal from within, and any well-intended paints or sealers will be counterproductive.

Q: Recently on my walks I’ve noticed certain trees have dropped hundreds of leaves, leaving some branches bare and others sparse. It seems that it’s one variety of tree. Is this caused by the weather, or is it a disease? — Carmen D.

A: From the photo you sent of the leaves, the trees losing leaves are ash. The slight curling or cupping of parts of the leaves, along with leaf lesions, indicate the likelihood of the fungal disease called ash anthracnose.

Ash anthracnose, along with a slight disfiguration of leaves, also causes leaf drop, which is why the ground below the affected trees becomes littered with leaves.

The fungal disease is most common during cool, wet weather conditions like we’ve had this spring. An ash tree can lose up to 25% of its foliage without causing undue stress.

Fungicides are mostly preventive, and once the disease is causing leaves to drop, the window for effective application has already passed. Large, mature ash trees would be difficult to treat.

Ash trees have battled this disease for many decades, and although it can weaken trees, generally they persist and nature takes its course.

There’s a much greater ash problem on the horizon, and that’s the insect called emerald ash borer that has decimated ash tree populations across a great swath of the United States. The insect is also present in Minnesota, Winnipeg and South Dakota and continues to move.

Although it’s been discovered at North Dakota’s Red River doorstep, it hasn’t been caught yet in-state, although it is almost certainly here.

Q: I’ve got some trumpet-type lilies that I’d like to move. When would be the best time? I don’t want to lose them. — Anne M.

A: The preferred time to dig and move true bulb-type lilies is in the fall, around September. Most will be blooming in June and July and are now in very active growth. Moving them now would cause greater stress than waiting until fall.

If a lily absolutely must be moved, such as when a house is sold, they can be carefully dug and potted, keeping as much soil intact as possible, although there is a much greater chance of something going wrong, versus waiting until the preferred fall date.

If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at donald.kinzler@ndsu.edu . Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.