Thanks to everyone who asked questions last year. I love reading the posts and every week we post the most interesting questions. Thanks for sharing your successes and challenges. Below is a summary of the three most frequently asked questions this year.
Question. Many homeowners submit photos of their birches showing dead or dying branches in various stages, mostly in the upper half of the tree. Many were interested to know whether their birch was affected by any disease and whether it would spread to other tree species.
A: Illness was not to blame. In almost all cases, I was able to see traces of an insect called the bronze birch borer, as the beetle leaves a visible D-shaped exit hole on the tree trunk as the infestation progresses.
As the borer makes its way under the bark, a sinuous series of raised undulations is revealed, giving the stem a "muscular" appearance. In the early stages, yellow, sparse and stunted leaves appear on the upper branches, leading to stem and eventually branch dieback. Trees can dry out for several years before dying.
Birch trees thrive in cool, moist conditions. The bronze birch moth may recognize birch trees affected by the heat and drought of 2021 and 2022, and may explain the outbreak. The insect affects only birches, it does not attack other types of trees.
The best protection is to water birch trees well during dry periods and mulch the root zone with shredded bark until soil temperatures are moderate. Unfortunately, there is little that can be done to alleviate prolonged heat stress.
Insecticides can be applied topically to kill larvae as they enter. If the moth has already landed on the tree, you can try systemic insecticides. But when large areas of the crown are affected, it is often too late to save the tree.
Question : A common question about tomatoes this year and many years to come is how to prevent large, sunken, brown or black spots from appearing on the underside of the tomato fruit, opposite the stem end.
A : The disease is called end rot and it is not a disease. Instead, the tomato plant can't use the soil's calcium and pulls it out of the developing fruit, leaving leathery, sunken areas.
Calcium is abundant in most regional soils, so adding more can be counterproductive. Instead, the plant cannot access the existing ore for various reasons. Growing too close together can break the roots, preventing them from extracting calcium from the soil.
Soil that fluctuates between wet and dry is the most common cause, as the roots must absorb calcium from the soil in aqueous solution, so moisture must be readily available. Maintaining even soil moisture in late June by mulching is the best prevention, along with frost-tolerant tomato varieties.
Question. Spruce trees with dead or dying needles were also at the top of the list of questions. Most of the fine brown needles on featured Christmas trees are on the lower half of the evergreens.
wall Diagnosing brown or thin needles on a Christmas tree requires a lot of research because there are many causes with similar symptoms. Spruce trees growing in wet, poorly drained soil are often susceptible to pine disease, but drought can also be to blame.
Low fertility, pesticide drift, site destruction, flooding, sap damage, improper planting, insects, and disease can cause needle drop. Deciphering the cause of each individual case requires gathering enough evidence to make a diagnosis.
If you have questions about lawn or yard care, please email Don Kinzler, NDSU Extension-Cass County, at donald.kinzler@ndsu.edu . General questions may be asked, so please include your name, city and state for proper advice.
