Oak Wilt 

Ceratocystis fagacaerum

"The creation of a thousand forests is in one acorn."

                                   Ralph Waldo Emerson 

Oak Wilt

Prompt diagnosis is necessary!  

For verbal diagnosis our fee is $150; for a laboratory testing diagnosis our fee is $225.

The diagnosis includes consultation regarding plan of action and preventative measures.  We, at the Gardens are able to treat your oak and other trees for any health issues that may present themselves.  For oak wilt preventative, we have two systems - macro infusion and micro trunk injections.  Oak wilt symptoms and preventative treatment systems are listed below.

Many homeowners are receiving a diagnosis of Oak Wilt, when actually the health issue with their oak tree is Anthracnose or the Two-line Chestnut Borer.  Anthracnose and two-line chestnut borer damage is commonly misdiagnosed as oak wilt.  Many homeowners are removing oaks that have been misdiagnosed...although anthracnose and two-lined chestnut borer can be a precursor to oak wilt, there are measures that can be taken to improve the health of the anthracnose and two-lined chestnut borer diagnosed tree and stave off the possible next step of oak wilt.

(Anthracnose, Two-lined Chestnut Borer & Oak Wilt symptoms below)

Isolate diseased trees from healthy trees!

Quercus - Oak Wilt

Treat healthy oak trees with fungicide micro trunk injections or macro infusions as a preventative!  

Oak wilt is a lethal disease caused by the fungus Ceratocystis fagacaerum. The fungus inhabits the water conducting vessels of the tree, and all species of oaks are susceptible in varying degrees. The fungus disrupts water movement to the crown and the leaves by plugging the vessels and eventually the foliage wilts and falls to the ground. Red and pin oaks typically die within 4 to 6 weeks of infection, while white and bur oaks have more resistance and may survive if only a small percentage of the tree is diagnosed with the disease and treatment is started immediately.

Most of the underground spread of oak wilt is through root grafts (root-to-root contact) between adjacent trees. Red oaks are social below ground and interlock and graft below the soil; they also share nutrients, water, elements and sap.  White oak trees are not as social.

It can also be spread by sap feeding beetles(Picnic beetle) (Nitidulidae) or bark beetles (Scolytidae) carrying fungal spores from tree to tree.


The primary symptom of oak wilt is the wilting of leaves and defoliation. The foliage in various areas of the canopy may have a very glossy or oily look before browning appears and they drop. Browning begins on the margin of the leaf and moves inward, and there is a distinct line between dead tissue and living tissue. Leaves normally fall before they have completely browned. In red and pin oaks, wilting progresses from the top of the canopy downward, while in white and bur oaks the wilting may occur on branches scattered throughout the tree.


 Streaking of the sapwood beneath the bark is a sign of the defense response of the tree and provides further evidence of oak wilt. An additional sign of the disease is the presence of fungal spore mats on red and pin oaks. They split the bark open and attract insects with their fruity odor.  These fungal mats do not appear until after the tree is dead or declining and usually the season after death, i.e: tree dies in fall, the fungal spore mats may show up the following spring.  The fungal mats are produced primarily in the spring and cooler seasons and they are found on red oaks in various degrees of decline.  The fungal spores live or are viable for disease spread for two to three weeks.

This is how oak wilt spreads over ground.  The mats produce a fruity odor that attracts the beetle. Fresh pruning or storm damage wounds on oaks attracts the beetle also.  The sap sucking beetle carries the spores from tree to tree and infects new trees.

Also, remember .... never prune your oak trees in the summer. We at the Gardens, never prune oaks (unless an absolute emergency) until the temperature is a consistent 40 degrees or below.  There are many sites that say that pruning oaks is fine after July. The beetles emerge during what is called degree days.  If the season starts early or ends late because of temperatures (degree days), the beetle will still be out or emerge early.  The beetle does not understand that it is July and it is supposed to disappear for the season; it is the temperature that determines its emerging or hibernation - so to speak.  That is why we make sure to prune oaks in temperatures that the beetle cannot withstand.

If removal of a diseased oak is necessary in the spring, summer, or fall, trenching is necessary to break the grafting between other oaks on the property.  Even if oak wilt is not present on your property; it is recommended that oak trees be removed in the designated degree days - late fall through winter.  If storm damage occurs in the spring, summer or fall, and pruning is necessary, wound paint all cuts.

If you are worried about your oak trees, please contact us. The Arborists will diagnosis your oak trees and recommend a treatment plan. Oak wilt can be treated if diagnosed early enough in white oaks and must be treated (preventative) in red oaks before the disease is diagnosed.  Remember there is no cure for oak wilt - only preventatives and possibly a suppressant

Although we do not recommend treating trees when they are not 'sick,' we do feel that it is necessary to prevent the spread of oak wilt.  If a tree on your property, a tree on your neighbor's property, or a tree in your neighborhood has been diagnosed with oak wilt; contact Victorian Gardens for a consultation as to how to prevent the spread of oak wilt to the 'healthy' oak trees on your property.  The distance to be concerned about is approximately two or three city blocks.

It is important to follow a strict policy of sterile pruning during the season or degree days that the beetle is present and also remember to only prune when it is necessary, i.e:  storm damage, mower damage, weed whip damage, hazardous limb or tree, etc.  All material from a red oak prune or removal (whether infected or not) must be chipped, burned, or covered with a tarp. 

Oak Anthracnose

Oak anthracnose is a foliar fungal disease, (Apiogniomonia quercina) that causes darkened spots and lesions on infected leaves.  Most of the time, a tree can survive anthracnose and life can be extended, but without diagnosis and treatment the foliage loss can become detrimental to the tree's health - severe diagnosis, repeated defoliation reduces the tree's resources and allows the tree to become susceptible to pest attacks.

Two-line Chestnut Borer

This borer attacks all oaks.  Symptoms will include dieback (loss of foliage) at the end of foliage, discolored foliage and foliage that wilts and suddenly turns brown and drops to the ground below.  Twigs and branches die back because of the larvae from the borer tunneling through the cambium (the vascular system of the tree).  The tunneling destroys these vessels which make it impossible for water and nutrients to reach all parts of the tree.  This is called girdling.  

Death to the tree if not treated occurs from one to five years.

Treatment is necessary to alleviate the stress from anthracnose and two-line chestnut borer loss of foliage and to prevent the attack of pests.  Preventative actions need to be taken when addressing oak wilt...correct diagnosis, plant health care and possibly macro infusion or micro trunk injections as a preventative.

Treatment Systems and Products


AGAIN- We at the 'Gardens' feel that it is necessary to care for the oaks in our State.  The oak tree is an integral part of our canopy of trees for the State of Michigan. Therefore we are in favor of preventative measures to save our oak trees. 

The first preventative is to prune only at the appropriate degree days.  The best time to prune is December to February.  It is possible to prune in November, but the temperature must remain at 45 degrees or less for at least 10 days.  We, at Victorian Gardens, prefer 38 to 40 degrees or less for an extended period of at least 10 days.  Pruning cuts or wounds during this time will not cause the spread of oak wilt.  If pruning is necessary in the moderate to high risk months, it is necessary to prune and paint cuts with wound paint - cut and paint!  Always remember, no matter what time of year or what species of tree is to be pruned, no arborist should use spurs or spikes to climb your tree.  Spurs or spikes are only to be used when removing a tree.

The second preventative measure: If oak wilt has been diagnosed in your neighborhood, township, county, village, please contact us to inject the red and white oaks on your property as a preventative measure.  We have two different systems available for oak wilt treatments.  We will discuss and choose with you which system will benefit your tree the best depending on the distance the oak wilt is in proximity to your oak tree.

We are not in the habit of treating trees that show no sign of disease, fungi, or pest.  Oak wilt may not be present in your yard, but the treatment is a preventative.  Similar to vaccinating your children for chicken-pox or the measles - a preventative measure. You cannot control, even with an appropriate best management practices pruning schedule, the weather.  Storm damage can occur.  If the storm damages your red oak in the summer months, then your oak is susceptible to oak wilt.  With preventative injections, the chances of oak wilt affecting your tree is substantially lowered. There is always a chance that treatments are not successful.  We estimate the treatments are 90% effective. We, as residents and homeowners, need to protect the canopy.  

Both of our systems use a product with the active ingredient of Propiconazole.  Propiconazole is the active ingredient that the latest research and studies have shown to prevent the spread of oak wilt, has saved white oaks when infected, and is a preventative treatment for non-infected red oaks.  Alamo, Shepherd and Propizol are brand names, but all contain the same amount of Propiconazole as their active ingredient.





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