Above- ground oak wilt infection can generally be prevented by not wounding oaks from April through July when (1) oaks are most susceptible to infection, (2) the oak wilt pathogen is commonly producing spores, and (3) the two sap beetle species most responsible for carrying spores are abundant.
As such, you should cut down oak wilt trees in either fall or winter, when your trees are dormant or entering dormancy, to minimize the risk of spreading the infection. If you cut down an infected tree that is partially alive in spring or summer, the disease can easily spread to other trees in your yard.
It is recommended to avoid pruning any oak trees throughout the growing season which is April 1 - November 1. Overland spread of the disease occurs mainly by sap feeding beetles that pick up fungal spores and carry them to freshly pruned (or wounded), healthy trees.
Oak wilt is most active from April to July, which is why you should never trim oak trees in the summer. To be safe, you should avoid pruning between April 1 and November 15. Davey arborists recommend pruning oak trees between November 15 and March 31.
Live oaks go through a process called molting every year when the weather starts warming up after winter. Molting is the process when live oaks drop at least 50% of last year's leaves and then grow back fresh leaves within the next month or so. Typically, this would start around March or April.
Most leaves abscise (fall) from deciduous trees in autumn. But, at about the time of bud-break in the spring, many oaks, beeches, and other woody plants go through a second phase of leaf-fall.
There are a few signs that you can look for to tell if a tree is overwatered. The leaves will start to turn yellow and drop off, the bark will start to peel, and the roots will start to rot. If you see any of these signs, it is important to cut back on watering so that the tree can recover.
Pruning mature oak trees at home is best kept to the smaller, lower branches that need pruning. Any branches up high in the tree should be left to a professional to cut.
A good indicator of oak wilt infection is a carpet of leaves under an oak in mid-summer. Red oaks infected with oak wilt lose about 90 percent or more of their leaves in 1–2 months; bur and white oaks quickly lose leaves from a few branches during the summer over several years.
As the beetles feed on the sap of the pruning cut, fungal spores get into the fresh wound, infecting the tree. Pruning oak trees in winter greatly reduces the risk of an oak wilt infection as the beetles and fungal mats are not present at that time of year.
If there is concern that a red oak may have been infected with oak wilt, then its wood should be immediately burned, buried, or chipped. Fire will kill oak wilt, and there is no risk of spores being transported by smoke.
If the roots are not completely removed, they can continue to grow and eventually lead to new tree growth. However, this process takes many years and is not guaranteed. Herbicide can also be used to kill the roots to prevent regrowth.
Look for wilting, yellowing, and premature leaf drop. Cankers may form at the base of the trunk, accompanied by a distinct mushroom growth near the tree base, particularly during wet conditions. Caused by various Armillaria species, this is an opportunistic disease because the fungus targets weakened or stressed trees.
While high risk of infection decreases to lower risk after mid-July, it's prudent to simply avoid pruning oak trees from just prior to bud break to leaf drop. This means April to November.
Fungicides have been developed that may be effective in preventing oak wilt when injected into living oak trees without active symptoms. A single treatment can protect red oaks from developing symptoms for 2 years following injection.
Live oak trees infected with oak wilt usually die within two to four months.
While the best time for tree treatment may be in the spring after the new leaves have set, successful treatments can be made at any time that there are sufficient green leaves on the tree to be treated. We've found that if the Oak Wilt threat is imminent, a treatment should happen soon to avoid major damage.
Oak wilt has been identified in over 20 states. Once an oak tree is infected with the oak wilt fungus, the tree will die and there is no treatment to save the tree. When an oak wilt infection is confirmed treatment can be applied to the surrounding trees to prevent the spread of this disease.
The disease is a particularly serious problem for species in the red oak group such as northern red, northern pin and black oaks. Once wilting symptoms are apparent on a red oak, the infected tree will lose most of its leaves and die within approximately one month.
Oaks in general do not require much maintenance and when pruning is needed it is best to do it in the winter months or early spring, between November and March.
The closer to the tree's trunk roots are cut, the more significant and harmful the damage will be. The 25% Rule – Never cut roots beyond 25 percent of a tree's total volume. The tree may die or fall as a result of this.
This is a naturally occurring process with live oak trees. Your tree isn't losing its leaves because it is dead or dying, but it loses its old leaves to make room for new leaves. While most trees lose their leaves in the winter, live oak trees drop their leaves in January through February.
Leaves Turn Brown and Wilt
While it might seem counterintuitive, overwatering can lead to brown and wilted leaves just as underwatering can. Excessive moisture prevents the roots from absorbing nutrients properly, causing the leaves to lose color and vitality.
Most of the root system occurs within the top three feet of soil. In shallower soil, the root system is concentrated in an even shallower zone, typically one to two feet below the surface.