Fireaxman
ArboristSite Guru
Engraver Beetles
I think I have all 3 species of engraver beetles. Katrina, mild winter, no rain. Been expecting them. But I need to know more about them before I start cutting down everything within 50 to 100 feet of the infected trees. [Does that distance sound right? source http://www.bugwood.org/pestcontrol/insects.html. I thought I remembered needing more space than that. ] I tried to get a picture; sorry about the focus. No Macro lense for the camera. But from the pictures I have found on the web, with my eyesight I would need a microscope to tell the difference between SPB and Ips (round butt vs. indented butt? On such a small bug?)
On some of the trees the whole crown is turning brown very suddenly (SPBB I assume). Others seem to be dying one branch at a time (IPS?).
Under the pitch tubes I usually find the larger, black beetle. The smaller, brown ones just scatter in groups of 3 or 4 whenever I scrape the bark down to the cambium. I have studied several threads in the Arboristsite forum, gotten some excellent information from a couple of June, 2005 threads. But I still have a few questions:
1. It sounds like the pitch tubes are on the entrance holes only. I also see a number of exit holes with no pitch tubes. Does that mean a lot of the beetles have already left the tree, or do they tend to exit the outer bark only to re-enter the same tree? I ask this because I am looking for a risk indicator for neighboring trees. I thought maybe if I dont see a lot of exit holes I might be catching them early enough not to have to remove neighboring trees.
2. Any "Rule of Thumb" as to how many pitch tubes indicate a probable fatal attack on the tree? Heavy infestations are obvious of course. But specificly I have one 90 foot tree I would like to leave that has 20 or 30 pitch tubes in the top 1/3 of the canopy. We are having a bad drought, but this tree is only 20 feet from a pond. All the pitch tubes are sealed (I know there is some debate on whether or not this means anything) and this particular tree somehow escaped major Katrina damage. Canopy is still dark green.
3. Another tree I would like to spare shows no pitch tubes and no exit holes, but the canopy is a significantly lighter shade of green than the neighboring trees. It is also fairly close to the pond, 50 feet. Should I assume from the lighter shade of green that it is fatally infected, or can there be other reasons for the color difference?
4. Does the height of the infestation offer any clues as to which beetle is responsible? Of 9 eighty to 100 foot loblollies 3 dead trees and 5 living ones with dead branches all have pitch tubes and exit holes in the top 1/3 to 1/2 of the canopy only. One has pitch tubes only, in the top 10 feet only. I think I saw somewhere that Ips attacks the top, SPB attacks midsection, and Black Turp. attacks bottom. Is this fairly reliable?
5. I have read that Ips can be self limiting, taking just unhealthy trees. If it is mostly Ips, can you manage them by just removing infested branches?
6. Some of the affected trees are in a subdivision and can be watered and fertilized. Following a drought, how long does it take for increased production of sap after water becomes available?
On those sites where I think I have Ips, and healthy trees all around the infested ones, I am inclined to help the healthy trees battle it out rather than remove them. If I am sure I have mostly SPB it may be wasted effort- cut 'em down.
I would appreciate any advice. Obviously this is going to cost me a lot of money and time . And it is really hot work down here right now.
I think I have all 3 species of engraver beetles. Katrina, mild winter, no rain. Been expecting them. But I need to know more about them before I start cutting down everything within 50 to 100 feet of the infected trees. [Does that distance sound right? source http://www.bugwood.org/pestcontrol/insects.html. I thought I remembered needing more space than that. ] I tried to get a picture; sorry about the focus. No Macro lense for the camera. But from the pictures I have found on the web, with my eyesight I would need a microscope to tell the difference between SPB and Ips (round butt vs. indented butt? On such a small bug?)
On some of the trees the whole crown is turning brown very suddenly (SPBB I assume). Others seem to be dying one branch at a time (IPS?).
Under the pitch tubes I usually find the larger, black beetle. The smaller, brown ones just scatter in groups of 3 or 4 whenever I scrape the bark down to the cambium. I have studied several threads in the Arboristsite forum, gotten some excellent information from a couple of June, 2005 threads. But I still have a few questions:
1. It sounds like the pitch tubes are on the entrance holes only. I also see a number of exit holes with no pitch tubes. Does that mean a lot of the beetles have already left the tree, or do they tend to exit the outer bark only to re-enter the same tree? I ask this because I am looking for a risk indicator for neighboring trees. I thought maybe if I dont see a lot of exit holes I might be catching them early enough not to have to remove neighboring trees.
2. Any "Rule of Thumb" as to how many pitch tubes indicate a probable fatal attack on the tree? Heavy infestations are obvious of course. But specificly I have one 90 foot tree I would like to leave that has 20 or 30 pitch tubes in the top 1/3 of the canopy. We are having a bad drought, but this tree is only 20 feet from a pond. All the pitch tubes are sealed (I know there is some debate on whether or not this means anything) and this particular tree somehow escaped major Katrina damage. Canopy is still dark green.
3. Another tree I would like to spare shows no pitch tubes and no exit holes, but the canopy is a significantly lighter shade of green than the neighboring trees. It is also fairly close to the pond, 50 feet. Should I assume from the lighter shade of green that it is fatally infected, or can there be other reasons for the color difference?
4. Does the height of the infestation offer any clues as to which beetle is responsible? Of 9 eighty to 100 foot loblollies 3 dead trees and 5 living ones with dead branches all have pitch tubes and exit holes in the top 1/3 to 1/2 of the canopy only. One has pitch tubes only, in the top 10 feet only. I think I saw somewhere that Ips attacks the top, SPB attacks midsection, and Black Turp. attacks bottom. Is this fairly reliable?
5. I have read that Ips can be self limiting, taking just unhealthy trees. If it is mostly Ips, can you manage them by just removing infested branches?
6. Some of the affected trees are in a subdivision and can be watered and fertilized. Following a drought, how long does it take for increased production of sap after water becomes available?
On those sites where I think I have Ips, and healthy trees all around the infested ones, I am inclined to help the healthy trees battle it out rather than remove them. If I am sure I have mostly SPB it may be wasted effort- cut 'em down.
I would appreciate any advice. Obviously this is going to cost me a lot of money and time . And it is really hot work down here right now.
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