AMBROSIA BEETLE - Ask Extension
I have a Norway Maple which I just discovered is infested with the ambrosia beetle. The tree is large, about 40 years old and I have taken good care ...
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AMBROSIA BEETLE #568456
Asked June 08, 2019, 1:42 PM EDT
I have a Norway Maple which I just discovered is infested with the ambrosia beetle. The tree is large, about 40 years old and I have taken good care of it, with professional pruning and fertilization each year. I understand that most species of Ambrosia Beetle primarily attack dying or stressed trees. The tree is certainly not dying but my tree service days that perhaps it became stressed due to excessive rain this year. I have another Norway maple on the other side of my house with the same infestation, but curiously, none of my neighbors' trees seem to be affected. No external damage is apparent other than the appearance of frass tubes on the lower trunk and saw dust-like material at the base. My tree service sprayed with a permethrin product and with Reliant Antifungal (a phosphonate fungicide) mixed with a surfactant by Quest Products called Pentra-Bark which is supposed to increase the systemic absorption of the antifungal. Is this an effective treatment? I understand that the beetles and their larvae do not directly injure the tree but that the fungus brought in by the female beetles to feed the larvae does harm the tree. It is my impression that the larvae mature within the tree and eventually leave as adults. Is that accurate? If so, how long does that take, and what is the scenario when they leave. What evidence will I see that they are leaving? Will I see evidence of boring? Will I see saw dust and/or frass tubes? If so, how do I distinguish this from a new infestation with new beetles entering the tree. When they exit, do they leave the area or do the males mate with the females and the fertilized females re-bore into the same tree to lay eggs? What is the chance of a successful outcome? What should I look for? Are infestations limited to the lower trunk or do the beetles also enter higher and on the branches. If they do, it would seem that insecticide treatment would be impractical. In such a case would treatment be possible? Any other recommendations? I know that I have presented many questions and I hope that you can address each one. Thank you.
Baltimore County Maryland
Expert Response
Take a look at the following page on our website, which will answer a lot of your questions. https://extension.umd.edu/ipm/landscape-management-nursery-production/ambrosia-beetles-maryland
There are three generations of Xylosandrus species per year and their emergence/activity is tied to weather conditions. They are attracted to ethanol produced by stressed trees. Pyrethroids have been found to provide control of attacking adults if applied prior to the closing of the galleries with frass. Once the galleries are closed off, treatments are not effective on the beetles. Systemic treatments are not effective. Fungicides do not inhibit fungal establishment/colonization.
There is much more information in this presentation document by our Extension entomologist. https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/ipmnet/2017%20Ambrosia%20beetle%20talk%20-%20Stanton%20Gill.pdf
Christa
You provided a link to "Ambrosia Beetle Control and Understanding How and Why they Attack Certain Plants" where is states:
"To Obtain copy of lecture go to www.IPMnet.umd.edu. Go to lectures and download PDF of lecture after Oct 1 2017"
When I tried to access this page, it said PAGE NOT FOUND. Do you have another URL?
Also, please let me know if the adult beetles leave the affected tree when they mature and if there signs of their leaving such as sawdust and/or frass tubes. After the adults emerge, do they mate and bore again into the same tree?
Here is the link that you were referring to. Scroll down to see the lecture.
https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/ipmnet/2017%20Ambrosia%20beet...
There are three generations of the ambrosia beetles. They do tend to come back in the same trees. When they leave you will see holes and some sawdust, may not see frass tubes. The arborist has provided the preventative treatment and there is nothing else you can do but keep the trees as healthy as possible. Water during dry periods and make sure mulch is no thicker than several inches and keep away form the trunk.
Marian
https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/ipmnet/2017%20Ambrosia%20beet...
There are three generations of the ambrosia beetles. They do tend to come back in the same trees. When they leave you will see holes and some sawdust, may not see frass tubes. The arborist has provided the preventative treatment and there is nothing else you can do but keep the trees as healthy as possible. Water during dry periods and make sure mulch is no thicker than several inches and keep away form the trunk.
Marian
In reference to the Norway Maples previously discussed, as stated, the trees were sprayed by a tree service with permethrin on 6/6/19. I plan to do subsequent permithrin applications myself. I see such a product online (permethrin SFR 38.8%). They have indicated that for ambrosia bettles, it should be diluted at a ration of 1.25 oz (of the 36.8% solution) per 1 gallon of water. I calculate this to be a 0.36% final solution.
(1) would that be the proper strength?
(2) assuming that I caught the infestation early on 6/6, when should the next treatment be? I have read that permethrin has a residual of 30 days (I don't know if that is correct). I know that I cannot kill the beetles while they are within the tree, but I believe that after a while, the adults will emerge, mate, and perhaps re-enter the tree. It is at this point which I believe I should treat. I need your help in timing when this may be. Is there any danger in over treating. Let's say that I treat every 30 days for a couple of months in order to hit the beetles when they emerge. Is that advisable? When they emerge will I see sawdust and/or frass tubes again? (3) surface roots were infested also. Is it safe to spray them?
(1) would that be the proper strength?
(2) assuming that I caught the infestation early on 6/6, when should the next treatment be? I have read that permethrin has a residual of 30 days (I don't know if that is correct). I know that I cannot kill the beetles while they are within the tree, but I believe that after a while, the adults will emerge, mate, and perhaps re-enter the tree. It is at this point which I believe I should treat. I need your help in timing when this may be. Is there any danger in over treating. Let's say that I treat every 30 days for a couple of months in order to hit the beetles when they emerge. Is that advisable? When they emerge will I see sawdust and/or frass tubes again? (3) surface roots were infested also. Is it safe to spray them?
Ambrosia beetle activity is dependent upon weather and temperature and treatments would be most effective when you see the first signs of wet staining on the branches -- an indicator of beetles beginning to bore into the tree. Yes, you will have to dilute the product according to the label directions, as you have calculated. We do not recommend applying a treatment every 30 days. It would be a waste of time, money, and product to treat when the timing is not right. When the beetles leave the tree, you will see holes and some sawdust-- you may not see frass tubes. Look for wet/stained areas on the trunk and roots and then treatment can be applied.
Landscape professionals use traps to monitor when the beetles are active and then apply the treatment when the timing is correct. Ambrosia beetles are attracted to ethyl alcohol which is produced by trees that are stressed. The beetles may be a persistent problem if the stressors cannot be addressed. There is more information here from NC State. https://content.ces.ncsu.edu/granulate-asian-ambrosia-beetle-1
Christa
Landscape professionals use traps to monitor when the beetles are active and then apply the treatment when the timing is correct. Ambrosia beetles are attracted to ethyl alcohol which is produced by trees that are stressed. The beetles may be a persistent problem if the stressors cannot be addressed. There is more information here from NC State. https://content.ces.ncsu.edu/granulate-asian-ambrosia-beetle-1
Christa
I had my trees pruned and I used some of the removed branches to make ambrosia beetle traps. I drilled a hole in the wood and filled some with denatured ethyl alcohol and others with Purell hand sanitizer, which contains 63 percent ethyl alcohol. The highest concentration of the liquid ethyl alcohol could get was 70 percent. Is denatured OK? From the signs (frass tubes and sawdust), the beetles entered around the tree the first week in June. Can you give me any idea of when they might emerge? I have read in some reports that they take 55 days to mature. Is that accurate? I plan to spray with pymethrin. Does pymethrin have a residual effect, and if so, what is it, realizing that, being outdoors, it will be subject to rain. As far as the traps, I placed them in the proximity, but somewhat away from the trees because I feared that if I hung them from the trees, it would attract more beetles to those trees. Does my thinking make sense? Your answers will be appreciated.
I need to correct something from my last question (June 27, 2019, 6:21 PM EDT.
I spelled the name of the insecticide which I plan to use incorrectly. The correct spelling is PERMETHRIN
I spelled the name of the insecticide which I plan to use incorrectly. The correct spelling is PERMETHRIN
It is fine to use denatured alcohol for a monitoring trap. You can also subscribe to and follow the University of Maryland Integrated Pest Management (IPM Report). Information on ambrosia activity and emergence is provided in this report. https://extension.umd.edu/ipm/landscape-and-nursery-ipm-alerts
The lifecycle for ambrosia beetles is about 35-40 days from eggs to adult. This will be influenced by temperature.
Permethrin does have a residual effect for a minimum of two weeks at least. It can last longer but it will depend on weather conditions.
Christa
The lifecycle for ambrosia beetles is about 35-40 days from eggs to adult. This will be influenced by temperature.
Permethrin does have a residual effect for a minimum of two weeks at least. It can last longer but it will depend on weather conditions.
Christa
I have been in communication with you regarding an ambrosia beetle attack on my two Norway Maples. It was first noted by my tree service on 6/6/19 on which date they sprayed with permethrin. I have been waiting for evidence of the beetles leaving the tree, at which time I think I should spray again. On one of the trees, I noticed two small "wet spots" which I have read is characteristic of boring. There is a tiny hole in each wet spot, but I probed the hole with a hypodermic needle and found it to be only about 5-7 mm deep. No frass tube is noted. Could this shallow hole be an indication of an attack or an exit and should I spray at this time. I have set up traps made from maple branches, filled with ethyl alcohol, but I see no activity there.
The wet spots and holes are a sign that they are on their way in now. They go in shallow like you noted and then turn at an angle so you can't reach them.
Now would be a good time to treat.
Christine
Now would be a good time to treat.
Christine
I sprayed my trees as you suggested. Do the beetles attack all summer? It's about 5 weeks since the last spraying. As I said, I sprayed today. Do I need to spray every 4 to 6 weeks. I understand that the insecticide does not affect beetles which have bored into the tree. I hope that I can protect the trees from repeated attach by spraying. Is that logical? In my area, Pikesville area of Baltimore County, when to ambrosia beetles begin their attacks in spring? Should I wait to see signs before I spray?
As we have mentioned before, ambrosia beetles have three generations per year and their activity is tied to the weather and moisture conditions.
One of our entomologists tracks ambrosia beetle activity to determine the appropriate times when treatments will be most effective. This information is provided in our landscape IPM reports, which we encourage landscapers to use. These reports are available to the general public too. You can subscribe or read the reports online here: https://extension.umd.edu/ipm/landscape-and-nursery-ipm-alerts.
We do not recommend spraying every 4-6 weeks just to hope this will prevent the beetle activity. And we do not typically recommend that homeowners take on these types of spray treatments themselves. Perhaps it would be best if you work with a licensed pesticide applicator for this. Sprays should be applied according to beetle activity noted in traps or wet areas on the trunk/branches, as noted previously. Ambrosia beetles are attracted to stressed trees. If the tree is stressed due to underlying poor growing conditions, the beetles may be a persistent problem. This information on how to decide when to remove a tree may be helpful as you decide a further course of action. https://extension.umd.edu/hgic/topics/how-do-you-decide-when-remove-tree
Christa
One of our entomologists tracks ambrosia beetle activity to determine the appropriate times when treatments will be most effective. This information is provided in our landscape IPM reports, which we encourage landscapers to use. These reports are available to the general public too. You can subscribe or read the reports online here: https://extension.umd.edu/ipm/landscape-and-nursery-ipm-alerts.
We do not recommend spraying every 4-6 weeks just to hope this will prevent the beetle activity. And we do not typically recommend that homeowners take on these types of spray treatments themselves. Perhaps it would be best if you work with a licensed pesticide applicator for this. Sprays should be applied according to beetle activity noted in traps or wet areas on the trunk/branches, as noted previously. Ambrosia beetles are attracted to stressed trees. If the tree is stressed due to underlying poor growing conditions, the beetles may be a persistent problem. This information on how to decide when to remove a tree may be helpful as you decide a further course of action. https://extension.umd.edu/hgic/topics/how-do-you-decide-when-remove-tree
Christa
I see in the July 19 IPM report that 2nd generation of ambrosia beetles has been spotted on the eastern shore. I live in the Pikesville area. If they are on the shore, would they necessarily be here? About 2 weeks ago, I spotted some wet spots but NO frass tubes on one of my maples, and assuming that it was a possible ambrosia beetle attack, I sprayed with permethrin. We have had a lot of rain and I wonder about the residual affect of the spray. I have traps set up, but no evidence of beetles. Should I wait to see frass tubes or wet spots to spray again.
Also, what is the best time in my area (Pikesville) to have these Norway Maples fertilized? I have read that you should wait until after the leaves fall off. When do you suggest?
Also, what is the best time in my area (Pikesville) to have these Norway Maples fertilized? I have read that you should wait until after the leaves fall off. When do you suggest?
You will have to check your traps for activity. Permethrin binds to the bark and should be active.
In general, mature trees do not require fertilization. Woody plants receive nutrients from lawn fertilization if their roots are adjacent to or growing under the turf area. And they pick up nutrients from decaying mulches and leaves and from the minerals in soil. Fertilize only if there is a need such as limited new growth in the spring or pale leaves. Do a soil test for pH and nutrient deficiencies. Fertilize if results show a deficiency. See soil testing https://extension.umd.edu/hgic/topics/soil-testing
If you do fertilize, do it in the fall, between late October and early December, or in late winter or early spring between late February and early April. https://extension.umd.edu/hgic/topics/fertilizing-trees-and-shrubs
Marian
In general, mature trees do not require fertilization. Woody plants receive nutrients from lawn fertilization if their roots are adjacent to or growing under the turf area. And they pick up nutrients from decaying mulches and leaves and from the minerals in soil. Fertilize only if there is a need such as limited new growth in the spring or pale leaves. Do a soil test for pH and nutrient deficiencies. Fertilize if results show a deficiency. See soil testing https://extension.umd.edu/hgic/topics/soil-testing
If you do fertilize, do it in the fall, between late October and early December, or in late winter or early spring between late February and early April. https://extension.umd.edu/hgic/topics/fertilizing-trees-and-shrubs
Marian
