Q: I planted this bur oak on my boulevard about 17 years ago. It’s been a beautiful tree, but this spring, it looks like it’s dead or dying and the bark has this strange orange shredded appearance on branches and the upper trunk. Do you know what might be happening? — Rod Dahl, Fargo.
A: Thanks for the photo. North Dakota State University’s Extension Horticulture and Forestry team was just discussing this issue, which has become prevalent in several counties in the region. Bur oak is the most common victim of this damage, in which bark is stripped away from trunk and branches, leaving shredded remnants clinging to the tree, which are often orangish in color.
Woodpeckers are the culprit. They’re pulling off bark pieces in search of insect larvae. If enough of the bark and underlying tissue are destroyed, the tree can die or be severely injured. There is no remedy once the damage happens.
Preventing woodpeckers from attacking a tree is a challenge. If the damage is noticed immediately, applying sticky Tanglefoot to the area might discourage the woodpeckers to move along. Hanging aluminum pie tins in the tree sometimes frightens birds, although it’s unattractive and not always effective.
Researchers are checking if systemic insecticides containing the active ingredient imidacloprid could prevent insect larvae from moving into the trees, which might prevent woodpeckers from searching for them. It’s also possible this has become a learned behavior by woodpeckers, causing them to search oak trees, whether or not insects are present.
Q: My neighbor and I are having a disagreement. She says ants are necessary for peony flowers to open properly, but I don’t think it’s true. Can you settle the issue? — Linda M., Jamestown, N.D.
A: I hesitate to get in the middle of a peony spat, but you are right, ants are not necessary for flower buds to open. But there is a connection.
Healthy peony flower buds exude sap, which attracts ants to the sugary sweetness. Ants are good little insects, as far as plants are concerned. They don’t harm the peonies, and may even ward off a few harmful insects.
Although they often coexist, proving ants aren’t necessary is easily demonstrated in controlled conditions where ants are excluded from the plants. If peony flowers fail to open, possible causes include too-deep planting, lack of direct full-day sun, botrytis blight and competition from encroaching grass.
Q: I’m always unsure whether I should be using pruning sealers or a paint of some kind when I prune off tree branches. Will aerosol pruning sealers help the pruning cuts heal faster? — C. Hanson, Fargo.
A: We can all save our money, because pruning sealers offer no benefit and might actually harm the wounds they were meant to heal.
Pruning sealers were discredited decades ago by studying treated pruning cuts versus untreated. Untreated cuts and wounds recover faster than cuts to which sealers have been applied. Rather than seal out infection, wound dressings often seal in moisture and decay, creating a haven under which disease and rot organisms can flourish as they attack the wood.
It’s best to simply let wounds seal on their own. Trees don’t actually heal; instead, they compartmentalize wounds with layers of cells that prevent damage from spreading any further. A properly pruned tree or shrub will seal off wounds naturally and prevent decay organisms from entering.
If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at firstname.lastname@example.org or call 701-241-5707. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.