Tree Problems in Cobmoosa Shores
We have been facing serious problems regarding the trees in Cobmoosa Shores Association (CSA). So far we have documented the presence of the Hemlock Wooly Adelgid (HWA) and Oak Wilt in Cobmoosa Shores. In response, the Cobmoosa Board of Trustees has established a Tree Committee with board member Paul Jordan as chair and serving with association members Jill Dedic, Cheryl Jordan, Janis Morrison, and Ernest Ryan.
The purpose of this committee is to learn about the infestations/diseases infecting our trees and to disseminate this information to our Cobmoosa community, and to plan how to protect the trees along the CSA roadways. We have enlisted the help of local agencies (such as the Oceana Conservation District and Muskegon Conservation District) to assess and monitor the trees within Cobmoosa Shores, and to save as many trees as we can. We are working with the full board to develop a long-range course of action to protect the natural beauty of Cobmoosa Shores.
We have received assistance from Kara Cronk (Muskegon Conservation District), Rod Denning (District Forester, Michigan Forestry Assistance Program), Drew Rayner (West Michigan HWA Coordinator, Michigan Department of Natural Resources), and Keely Dunham-Adkins (West Michigan CISMA Coordinator).
HWA and Tree Committee Action
The most recent focus has been on the threat to our trees from the Hemlock Wooly Adelgid (HWA). With Jill Dedic taking the lead, a hemlock database has been established, recording hemlocks on CSA property and we continue to track treatment and progress of those trees. Designated Tree Committee volunteers, Paul Jordan and Ernie Ryan, have treated some infected hemlocks on CSA property but much of the work has been contracted out to Muskegon Conservation District (MCD). That agency has created its own database, in which every treated tree is identified by its geolocation and lot number. In addition, the Association contracted with the Muskegon Conservation District to treat all other hemlocks on CSA property. This was completed in the fall of 2022. (Treatment with imidacloprid will probably have to be repeated in 2028 or 2029.) Additional ‘booster’ treatment is now being applied to specific larger hemlocks.
Our plan going forward is to monitor the health of the treated trees, taking stock through October and then reviewing them again next summer to assess progress, while providing further treatment for those trees that are struggling but are potentially able to be saved
Infested hemlocks that are NOT treated will die in 4-10 years. As of 2023, it appears that infected hemlocks in Cobmoosa are in year 3 to 4 of that 10-year process. As has been mentioned, in an effort to save these trees the ones that are at least 5” in diameter and on Cobmoosa property have been tagged and treated. Our committee has placed priority on saving the oldest (biggest) trees. However, the spread of the insects has been aided by mild winters since it does not get cold enough to kill off any of the wooly adelgids, and therefore infestations have been rapidly spreading
What We Have Learned About HWA
The Hemlock Woolly Adelgids are invasive aphid-like insects that have attacked hemlock trees along the east coast and has now spread as far west as Michigan. This non-native forest insect has killed hundreds of thousands of hemlocks so far. It threatens more than 170 million hemlock trees in Michigan forests. Evidence suggests that some of these infestations are at least 10 years old and probably originated when infested hemlock trees from other states were planted in landscapes in Michigan.
The purpose of this committee is to learn about the infestations/diseases infecting our trees and to disseminate this information to our Cobmoosa community, and to plan how to protect the trees along the CSA roadways. We have enlisted the help of local agencies (such as the Oceana Conservation District and Muskegon Conservation District) to assess and monitor the trees within Cobmoosa Shores, and to save as many trees as we can. We are working with the full board to develop a long-range course of action to protect the natural beauty of Cobmoosa Shores.
We have received assistance from Kara Cronk (Muskegon Conservation District), Rod Denning (District Forester, Michigan Forestry Assistance Program), Drew Rayner (West Michigan HWA Coordinator, Michigan Department of Natural Resources), and Keely Dunham-Adkins (West Michigan CISMA Coordinator).
HWA and Tree Committee Action
The most recent focus has been on the threat to our trees from the Hemlock Wooly Adelgid (HWA). With Jill Dedic taking the lead, a hemlock database has been established, recording hemlocks on CSA property and we continue to track treatment and progress of those trees. Designated Tree Committee volunteers, Paul Jordan and Ernie Ryan, have treated some infected hemlocks on CSA property but much of the work has been contracted out to Muskegon Conservation District (MCD). That agency has created its own database, in which every treated tree is identified by its geolocation and lot number. In addition, the Association contracted with the Muskegon Conservation District to treat all other hemlocks on CSA property. This was completed in the fall of 2022. (Treatment with imidacloprid will probably have to be repeated in 2028 or 2029.) Additional ‘booster’ treatment is now being applied to specific larger hemlocks.
Our plan going forward is to monitor the health of the treated trees, taking stock through October and then reviewing them again next summer to assess progress, while providing further treatment for those trees that are struggling but are potentially able to be saved
Infested hemlocks that are NOT treated will die in 4-10 years. As of 2023, it appears that infected hemlocks in Cobmoosa are in year 3 to 4 of that 10-year process. As has been mentioned, in an effort to save these trees the ones that are at least 5” in diameter and on Cobmoosa property have been tagged and treated. Our committee has placed priority on saving the oldest (biggest) trees. However, the spread of the insects has been aided by mild winters since it does not get cold enough to kill off any of the wooly adelgids, and therefore infestations have been rapidly spreading
What We Have Learned About HWA
The Hemlock Woolly Adelgids are invasive aphid-like insects that have attacked hemlock trees along the east coast and has now spread as far west as Michigan. This non-native forest insect has killed hundreds of thousands of hemlocks so far. It threatens more than 170 million hemlock trees in Michigan forests. Evidence suggests that some of these infestations are at least 10 years old and probably originated when infested hemlock trees from other states were planted in landscapes in Michigan.
Two hemlocks 10 feet apart on Ottawa Trail: The hemlock on the left (belonging to a member) has not been treated for HWA. (Note the white ‘cocoons’ at the bases of the needles.) The hemlock on the right (belonging to the CSA) was treated last year with imidacloprid.
HWA treatment can be done from mid-May to mid-October. Depending on what form of HWA treatment is used, hemlocks will need continued treatments every 3-7 years, for the life of the tree. There are two insecticides currently being used to protect our hemlocks: imidacloprid, which is slower acting agent and dinotefuran, which is taken up more quickly by the tree. There are two treatment methods that have been applied by the CSA in Cobmoosa Shores. These are as a bark spray and by injection through the bark into the sap-bearing layer of the tree. In each of these methods, the insecticide is strictly confined to the body of the tree itself. Even when the trees are dormant in winter, no insecticide will enter the ground. We take care to make sure that all of the chemical goes on the tree and not onto the ground. Quantities of insecticide are being monitored to ensure we are within the amounts allowed by the federal government.
These insecticides have never been and will never be applied by the CSA as a “soil drench”, where an insecticide solution is poured around the base of a hemlock. The reason for this is that it is extremely important not to risk either polluting ground water or endangering pollinating insects. Because insects do not play a role in pollinating hemlocks, bark spray or injection methods pose no risk except to insects that suck the trees’ sap (such as HWA).
Help for CSA Members on Member Property
The Muskegon Conservation District has been working with individual property owners in our association and has treated trees last fall and will continue this year. Many residents did sign up for survey and treatment of hemlocks on their property, at the individual property owner’s expense. Members who choose not to contract with MCD for treatment will not be charged for the survey of their hemlocks. Those who choose to contract will receive a bill for the survey as well as the treatment. Note that MCD is charging for only their costs of surveying and treating.
Any additional members who want to sign up with the Muskegon Conservation District for a survey and possible treatment of their hemlocks should directly contact Lance McCarty at [email protected].
Members Treating Their Own Trees
Homeowners can purchase HWA treatment products online or contact any local certified specialist for treatment options. These products can only be applied as listed on the product label. It is illegal for anyone to purchase these products on another’s behalf unless they are licensed in the state of Michigan. Please note, the board cannot authorize or undertake any form of treatment on the personal property of members. However, members of the Tree Committee will gladly confer with you in assessing your trees and offering suggestions on how best to proceed
Follow this link for a list of licensed pesticide contractors compiled by the Michigan Department of Agriculture.
For more information about treatment options, visit
Oak Wilt
Oak wilt is a fungal disease that moves through the vascular system (water conducting tissue) of the tree. The fungus spores are carried to the tree by small beetles that feed on sap from fresh wounds. These sap beetles that carry the disease from infected trees are attracted to fresh wounds from storm damage, pruning cuts or other injuries to previously uninfected trees. Once the beetles feed and the fungus moves into the vascular tissue, the tree reacts and tries to wall off the spread of the disease by plugging cells which causes branches to wilt. The disease can also spread from already infected oaks by moving through root grafts between trees of the same species. This is why oak wilt spreads so effectively between nearby trees. This is also why oak trees should not be pruned from April to October. It is the one thing each of us can do to slow if not halt the spread of Oak Wilt.
Oaks are divided into two groups, the red oaks and the white oaks. Red oaks (pin, black, and northern red) are more susceptible than the white oaks (white, bur, swamp white). Infected red oak trees can wilt and die within several weeks, while white oaks may survive for one or more years. A correct diagnosis is critical to reducing the spread of the disease. The first symptom is browning leaves at the top of the tree. Leaves brown from their margins at the end of the leaf and continues to progress along the margins and down towards the mid-vein and stem of the leaf. Whole branches may be seen yellowing and then browning as the disease progresses down the branch. This is first seen in late spring to early summer. Leaves litter the ground around the tree as the tree wilts. Another symptom is a fungal mat that grows under the bark, creating pressure causing bark to crack. These fungal mats attract sap beetles where the insects pick up spores of the disease, carrying it to uninfected trees that are freshly wounded, releasing the spores as they feed.
Cobmoosa Treatment Information
The Board established the Oak Wilt Fungicide Program. Please refer to the 5/22/20 News & Notes item on the CSA website.
For more information on Oak Wilt visit
· MSU Extension -- Oak Wilt in Michigan's Forests
· Oak Wilt Overview section of the Michigan DNR site,
You may also wish to visit the MSU College of Agricultural & Natural Resources.
HWA treatment can be done from mid-May to mid-October. Depending on what form of HWA treatment is used, hemlocks will need continued treatments every 3-7 years, for the life of the tree. There are two insecticides currently being used to protect our hemlocks: imidacloprid, which is slower acting agent and dinotefuran, which is taken up more quickly by the tree. There are two treatment methods that have been applied by the CSA in Cobmoosa Shores. These are as a bark spray and by injection through the bark into the sap-bearing layer of the tree. In each of these methods, the insecticide is strictly confined to the body of the tree itself. Even when the trees are dormant in winter, no insecticide will enter the ground. We take care to make sure that all of the chemical goes on the tree and not onto the ground. Quantities of insecticide are being monitored to ensure we are within the amounts allowed by the federal government.
These insecticides have never been and will never be applied by the CSA as a “soil drench”, where an insecticide solution is poured around the base of a hemlock. The reason for this is that it is extremely important not to risk either polluting ground water or endangering pollinating insects. Because insects do not play a role in pollinating hemlocks, bark spray or injection methods pose no risk except to insects that suck the trees’ sap (such as HWA).
Help for CSA Members on Member Property
The Muskegon Conservation District has been working with individual property owners in our association and has treated trees last fall and will continue this year. Many residents did sign up for survey and treatment of hemlocks on their property, at the individual property owner’s expense. Members who choose not to contract with MCD for treatment will not be charged for the survey of their hemlocks. Those who choose to contract will receive a bill for the survey as well as the treatment. Note that MCD is charging for only their costs of surveying and treating.
Any additional members who want to sign up with the Muskegon Conservation District for a survey and possible treatment of their hemlocks should directly contact Lance McCarty at [email protected].
Members Treating Their Own Trees
Homeowners can purchase HWA treatment products online or contact any local certified specialist for treatment options. These products can only be applied as listed on the product label. It is illegal for anyone to purchase these products on another’s behalf unless they are licensed in the state of Michigan. Please note, the board cannot authorize or undertake any form of treatment on the personal property of members. However, members of the Tree Committee will gladly confer with you in assessing your trees and offering suggestions on how best to proceed
Follow this link for a list of licensed pesticide contractors compiled by the Michigan Department of Agriculture.
For more information about treatment options, visit
- https://extension.psu.edu/integrated-approach-to-hemlock-woolly-adelgid-mitigation
- Insecticide Treatment for HWAOOO
- How to Treat
- Distribution of HWA in 2020
- HWA Infestation History in Michigan
- HWA in Oceana County
Oak Wilt
Oak wilt is a fungal disease that moves through the vascular system (water conducting tissue) of the tree. The fungus spores are carried to the tree by small beetles that feed on sap from fresh wounds. These sap beetles that carry the disease from infected trees are attracted to fresh wounds from storm damage, pruning cuts or other injuries to previously uninfected trees. Once the beetles feed and the fungus moves into the vascular tissue, the tree reacts and tries to wall off the spread of the disease by plugging cells which causes branches to wilt. The disease can also spread from already infected oaks by moving through root grafts between trees of the same species. This is why oak wilt spreads so effectively between nearby trees. This is also why oak trees should not be pruned from April to October. It is the one thing each of us can do to slow if not halt the spread of Oak Wilt.
Oaks are divided into two groups, the red oaks and the white oaks. Red oaks (pin, black, and northern red) are more susceptible than the white oaks (white, bur, swamp white). Infected red oak trees can wilt and die within several weeks, while white oaks may survive for one or more years. A correct diagnosis is critical to reducing the spread of the disease. The first symptom is browning leaves at the top of the tree. Leaves brown from their margins at the end of the leaf and continues to progress along the margins and down towards the mid-vein and stem of the leaf. Whole branches may be seen yellowing and then browning as the disease progresses down the branch. This is first seen in late spring to early summer. Leaves litter the ground around the tree as the tree wilts. Another symptom is a fungal mat that grows under the bark, creating pressure causing bark to crack. These fungal mats attract sap beetles where the insects pick up spores of the disease, carrying it to uninfected trees that are freshly wounded, releasing the spores as they feed.
Cobmoosa Treatment Information
The Board established the Oak Wilt Fungicide Program. Please refer to the 5/22/20 News & Notes item on the CSA website.
For more information on Oak Wilt visit
· MSU Extension -- Oak Wilt in Michigan's Forests
· Oak Wilt Overview section of the Michigan DNR site,
You may also wish to visit the MSU College of Agricultural & Natural Resources.