North American Fruit Explorers mailing list at ibiblio

["H.Dessureault" <inter.verbis@atreide.net>]

Fellows and fellas tree growers,

 

To follow up on the question I put to the group two weeks ago, here is a report on my borer, the flat head borer. The presence of this particular borer, infesting some of my trees, can be detected by a tiny little pile of reddish brown wood residue on the ground under a pin size entrance near the base of the tree. After having destroyed an area under the bark, relatively large as compare to their size, the white larvae eventually dig a gallery towards the roots where they become adults and where they do extensive damages to the root system in the process. You have to get the larva out as quickly as possible and that involves unfortunately cutting out the damaged areas with a knife in search of the beast. I had as many as four in one single tree of a 2 1/2 " diameter. I found two the first day, once I knew what to look for, and another one the next day. A few days later, I observed more reddish sawdust and found another one. All this in a 2 1/2 " tree! You have to get them out as soon as possible. The more time they spend in the tree, the more damage they do. Had I not noticed, I am sure that those 4 borers would have done enough damages to condemn that tree. All in all, I had to dig a large area on the side and underneath the tree where I followed one larva. The roots of that particular tree were chewed and destroyed (attacked from two sides) in a north south plane and the hole that I had to dig underneath the tree allowed to see the light on the other side. Fortunately, the roots on the east and west side of the tree were healthy and solidly anchored as I was able to observe as the day was unusually windy, which gives me hope for the survival of the tree.

 

Claude Jolicoeur, who provided very useful advice on the subject, had mentioned that in some cases pushing a flexible wire through the hole could work to kill the bug inside. While not being a solution for every circumstances since the larva changes directions, in one instance where I would have had to cut live bark to get to the larva, I used the wire instead and it worked. No more sign of activity, since.

 

The larvae are easily killed by rotenone. The adults don't like it but seem more resilient and they are able to run away. Unfortunately, it is a contact insecticide and dusting it on the bark or at the hole or even squirting it in the hole diluted in water is not sure to work as there is an extensive amount of wood excrement between the surface hole and the larva. Once you get to the larva, there is no sense using the rotenone as it is quicker to kill the larva directly.

 

I continue to check my trees every day for a late larva, but so far so good. In total, I had five trees attacked by these larvae and most had 1, some 2 and one had 4 larvae in different spots on the base of the same tree!

I had dug out a small dead tree recently, that had started to leaf out and had dried up, and all the root core was reddish brown and rotten. No doubt that the borers were at work last year. I had no idea then of the problem and I failed to notice.

The only good news is that these larvae, after the initial chewing of a relatively large area given their size, dig a gallery down and don't girdle the tree. But then, if they are many or if they attack the tree every year...

 

I intend to fix the damage that I have created with the knife by covering with a clay and a bit of cement mixture that is more liquid and not as hard as cement and I apply it thinly with a brush. I fill in the holes and gaps where insects have a tendancy to lay.

I also intend to paint the trunk of all my trees with lime this year, ahead of the flat head borer laying season, to see if it will stop this borer from laying its eggs.

 

A friend explained a method that he has seen of covering the base of the tree with a tube of corrugated cardboard a foot tall early August and removing them early winter to burn them... That might work, but I tend to shy away from labour intensive methods.

 

The beauty of the lime applications is that it is a bit like killing many birds with one stone. 

 

Borers are my worst insect problem ever, and what is worst it took me a few years to identify the problem. As I mention, I first though it was collar rot. I insist on this because, while not being very knowledgeable relatively speaking on the subject of apple tree growing, I have been at it for a while and I am very interested and usually very attentive to what is happening. And yet, it took me a long time to get to the bottom of this situation. Luckily for me I did not follow the advice of cutting down the first trees that showed borer damage as I would have been forever cutting down trees thinking it was collar rot... One has to be more weary of drawing quick conclusions.

 

I also have another type of borer which penetrates the tree through one hole and comes out another. If you squirt some water into the hole, you can see it come out the other hole. This borer seems to prefer bigger trees as I have only observed these holes in 4" tree and larger. The holes are the size of a pencil.

I have not identified the culprit yet. I suspect for the moment a shiny long worm that is shiny charcoal grey and has circular rings at regular intervals all along the body. At this time of year, this particular funny looking creature is curled up in the soil at the base of the tree (not a cut worm). Is anyone familiar with these...

 

I guess you can say that I am currently studying the ennemy.

 

Hélène, zone 3

 

 

 

----- Original Message -----

From: victoria l. caron

To: nafex@yahoogroups.com

Sent: Monday, June 25, 2001 6:31 AM

Subject: [nafex] quick bridge graft

Well I was a little miffed this weekend to see one of the dozen fruit trees in my yard toppled over from the wind. Close examination showed very obvious borer damage. Now maybe it was arrogance, but I have repeatedly been negligent in this department assuming it would NEVER happen to me. Wrong! This little tree has never hit five feet and has been there for five years. Some of this is due to the fact that it is a result of 'the tag said one thing and my notes something else.' Eventually giving up on what the tag said, I've been trying to make it into a multivar apple tree like several others I have made with good results. This tree consistently has little growth compared to its neighbors, not all of it due to my constant surgery.
Amazingly, there has been absolutely no wilting. I know this means something too. The grading stake that I use for small trees was also broken, so I staked the tree back up with a fiberglass electric fence post (to avoid more damage). Being on M7, the tree has lots of root suckers. I took three of these and wound them in a network pattern around the trunk to about one foot high. Over this I wrapped a very strong 1/2 in wide rubber band. I left about 1/4 to 1/2 inch between courses to admit air. If the theory (not mine but I agree) is correct, these suckers should, if held tightly enough, grow into and bridge the damaged area. I'm optimistic enough to hope that this operation could also solve the slow growth problem if I can watch for the bores from now on.
An update on several other experiments I tried this year:
- about the Davey tree that was completely girdled and to which I too quickly, without thinking, applied latex caulking to cover the entire girdling, including the cuts for the one bridge graft I managed to set over the lumpy original graft union - it is doing great! making lots of new growth. I suspect the bridge is working well but still won't know for some time the consequences of the caulking compound on the tissues.
- MSM used to supply sulfur to peppers - all the leaves slowly wilted and fell off. The flower buds remained and are starting to bloom, new leaves are appearing. Maybe it was too strong of a solution, about 1/4 tsp dissolved and shared by 4 peppers and 6 tomatoes. The tomatoes seemed less affected. Also, the second night after application, temps dropped to 32 on our deck where the plants were lightly covered. The plants that were treated with MSM were also on the outer edge of the tray furthest from the wall of the house, so there could have been some frost damage that the other peppers did not suffer. I have also noticed in the past that when we get our fall frosts, certain varieties of tomato plants seem able to take temps down to 28 degrees with no browning and keep ripening fruit for some time, while the peppers can succumb at 32. That may have happened here where my tomatoes (grape) were very well hardened off.
vic NH zone 3

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