CORVALLIS - Have a deciduous tree that doesn't look quite right this summer? Did some buds or entire branches never leaf out? Did all the leaves wilt?
Every year a number of people call their local county office of the Oregon State University Extension Service or the OSU Plant Clinic with questions about their deciduous trees not looking healthy or not leafing out as much as they should.
Diagnosing deciduous tree problems is not easy. Barb Fick, home horticulturist with the OSU Extension Service offers some hints at how to give your less-than-thriving tree a closer look:
Closely examine a branch where some leaves are normal and some of the buds never broke. Cut into a bud. Is it brown and dead inside? This means the bud died quite a while ago.
Is the bud brown inside, but green outside? This is probably cold injury, as the interior of the bud is most active metabolically, therefore more susceptible to injury from cold temperatures.
Is the twig and branch still alive? If it is, the wood underneath the bark will be green and not hard, brittle and dry. If a lot of the buds are completely dead, but the twig and branch is still alive there is a good chance that the tree has been growing poorly for a couple of years or more. Trees that have been putting on little growth are suffering from either a root problem or chronic stress. Trees planted between curbs and sidewalks are commonly stressed from a combination of heat, drought, compaction and air pollution. Make sure you water your trees deeply and regularly - once per week if it is a young tree and once a month if it is a mature specimen.
Did entire branches not bud out at all? This could be a symptom of disease. Maples, for example, may suffer from verticillium wilt. If you have a maple, cut into a suspected diseased branch along the long axis. If you see brownish streaking in the wood, the plant is probably infected with verticillium fungus. Prune off infected parts to control this disease. Some plants with this disease may die in a few weeks. Others may live for many years. There are no chemical controls.
Branches failing to bud out are also a symptom of problems including severe root rot, an infestation of root weevils, insects girdling the branch, and many other factors.
Did your tree leaf out then all the leaves wilt? This is a symptom of cold injury from sudden cold temperatures, as during last December.
Make some observations and notes and take samples. Then bring them into a Master Gardener at your local county office of the OSU Extension Service. They can help you figure out your problem.