Elm leaf beetle, treatment options

[Bermy]

I went to see a georgeous english elm today...it is approximately 4 metres DBH (running around it with a regular tape measure) prob 10m spread and 10m high.

It got hit very badly with leaf beetle this past summer, looked like a flame thrower had been deployed. Only about 20-40% of the drip line is accessible, tarmac drive, planting beds, buildings around it.

I want to find a licenced applicator to stem inject it, when is the best time? We are in very early spring here.

The HO told me.. (get this) the handyman who works for a friend, has a friend who can get hold of some 'Confidor' (imidocloprid) and he recommends soil injection... HA HA!
Then there was the suggestion, pyrethrum spray...

 

[Stumper]

Imidacloprid should be beneficial. Insecticidal soap is also a pretty good deterrent.....but during bad years it is hard to keep the beetles off completely.

 

[Bermy]

Yes but when is the best time to stem inject?

 

[Stumper]

Fiona, I don't know about stem injection....I believe that spring is considered ideal for best/most rapid transport within the tree. I am not a big injection fan having cut a lot of trees with notable injection related injuries. I like soil drenching ... and again spring is ideal.

 

[Bermy]

I hear you...just that there is so much tarmac over the root zone, and herbaceous borders, I'm not sure we could get enough product into active areas by drench to be effective.
Let me see if I can find the picture...

 

[Stumper]

Recommended application of Imidacloprid drench is at the base only. The logic is sound-The majority of "hair" roots are at the drip line but the greatest CONCENTRATION of absorbing roots are at the base of the stem so a localized application at the base is the most efficient use of product with the least effect on non targeted plants......and it is EASY.

 

[Underwor]

I will agree with Stumper. we use a lot of Bayer Tree and Shrub insecticide as a basal drench. Seems to work very good.

 

[Bermy]

Yes, I've used that in Bermuda...

Even next to the trunk is only barely accessible with a few daffodils around it. I'd have to build a dam of some sort to contain it...and isn't the recommendation to go at least a foot out from the trunk..., the flares go out that far, then some daffs, then the tarmac...hmmm, maybe dig up some tarmac...

And that stuff is one ounce per inch of stem diameter...I'd need a LOT! Tree is appoximately 160" in diameter
How much water would you dilute 160oz in? I think it says trees over 50" use 2 gallons but that seems awfully strong. And how much water would you wash it in with?

Have you ever damaged a big tree using Bayer drench?

 

[Stumper]

160" Diameter or circumference? In any case Dose is 1 oz per inch circumference......so at 160 you are looking at 5 quarts added to 2 gallons of water and then another bucket full of just water to wash it in. Even with limited soil exposure you can just take a little time and dribble it in.

 

[Stumper]

160" Diameter or circumference? In any case Dose is 1 oz per inch circumference......so at 160 you are looking at 5 quarts added to 2 gallons of water and then another bucket full of just water to wash it in. Even with limited soil exposure you can just take a little time and dribble it in.

 

[Bermy]

Sorry, yes, 160 circumference.

Next to see if thay have that product available here, they must do, probably called something different.