HWA treatment question

LWalton · Jan 16, 2019

1) What are the pro's and con's of using a combination of dinotefuran and imidicloprid (as a basal spray) to treat Hemlock Wooley Adelgid (HWA)?

Seems like you'd get both the faster action of the dino and the prolonged action of the imid. What am I missing besides cost concerns?

2) When should I begin spring/summer HWA treatments?
Weather-wise what should I be looking for? Sunlight? Rainfall? Temps?
Tree-wise what should I be looking for Buds? Leaves?

ATH · Jan 16, 2019

If you are planning now for Spring treatments, I see very little, if any benefit to dinotefuran. Treat the trees with a soil drench of imidacloprid as soon as the soil is not frozen and is not completely "slushy".

If you are treating a heavily infested tree in late May, June or July...absolutely I'd hit them with dinotefuran. Then put them on next Spring's treatment schedule for imidacloprid.

The other place dinotefuran has a is good: if you are trying to treat a lot of trees in a small area, don't want to inject imidacloprid, but are going to go over the oz/acre limit with soil applied imidacloprid. Dinotefuran can buy you a year. So I'd treat as many as you can with soil-applied imidacloprid (Batch A). Treat the rest with dinotefuran (Batch B). If you can treat all of Batch B next year with imidacloprid, you are all set. If there are still too many in Batch B, you'll need to make a Batch C that also get dino in the second year then imidacloprid in the 3rd year. You just need to keep good records of which trees are due for re-treatment which years if you do that.

The only place I'd trunk inject imidacloprid is in close proximity to water or where there just isn't enough soil. These would be great examples...

JD3000 · Jan 16, 2019

If that's your plan, time it for the Dino to be hot for crawler emergence. The Imid will provide a much longer residual but watch for mite flare ups.

Also depends on how many trees per acre you're dealing with as he mentioned.

A downside is Imid being poorly soluble so you'll have to shake your booty a lot to keep it in suspension. This can make Dino foamy so a couple drops of defoamer may be advised.

TsugaPHC · Jan 19, 2019

Imidacloprid isn’t absorbed through the bark like dino, no matter how much Pentrabark you add—it’s not soluble enough.

For me, if it’s not practical to do a hemlock spray with organic hort oil (tree is too big, too close to house, etc), I go straight to a dino trunk spray in mid-May. It gets in the tree fast, kills off the adelgid before they go into their summer diapause, and is out of the tree before the weather cools down and the mites become a problem.

It’s also a lot quicker to apply, and it’s a yearly repeatable service instead of every-other year like imidacloprid.

JD3000 · Jan 19, 2019

TsugaPHC said:

I thought so to but a couple studies or states now approve it for HWA. I'll look for it, I'm leaning towards Cornell but I'll find it soon...

ATH · Jan 19, 2019

I would never use a more expensive product just because it is an every year cash flow for me. If it is the better product to use for the pest, great. But if soil-applied imidacloprid cost less money and has a longer treatment period as long as you are not getting mite problems, that sounds like a much better deal for the clients...

JD3000 · Jan 19, 2019

Agreed, this option may be good for trees in the back 40 though.

Here's one I saw
http://blogs.cornell.edu/foresthealth/insecticide-treatment-for-hwa/

JD3000 · Jan 19, 2019

In any event, some great work has been done about optimal doses to treat this bug. They've found lower doses at some sizes of trees work just as well and may allow more trees to be treated per acre than what the label says.

Attached from Warnell is well worth a read for those involved. I read a gazillion papers for a hemlock presentation I contributed to for ODNR Forestry. If you want my PPT, let me know and I'll email it.

LWalton · Jan 19, 2019

Thank you all for your input. Treatment/acre is an issue. Following with what the company has done in the past (focused on Dino) may be an issue.

I thought I saw something somewhere about using wd40 as a de-foaming agent, but that sounds a bit wrong to me? What do you all use?

Would be very interested in that presentation.

ATH · Jan 19, 2019

Why? Actual defoamers are cheap...and labeled for use.

JD3000 · Jan 20, 2019

Yeah, just use an official defoamer

Russell Plumb · Jan 27, 2019

Dr Richard Cowles of the CT ag station released a paper last year saying imidacloprid has been found to have a 5-7 residual in hemlock and it also has been found to translocate through bark like Dinotefuran.
HWA took a big hit the last couple of winters from the cold, around 90% decline in New England so EHS is now more of an issue. Imidacloprid doesn’t work for EHS so Dino is our go to for large trees that knocks back both pests.
Neonicotinoids were made restricted use pesticides in CT last year and last week at the CTPA winter meet there was talk of them being banned altogether.
Dr Cowles also says pentrabark does not improve penetration for these products but still necessary for products like agrifos.

Acerxharlowii · Feb 9, 2019

Defoamers are great!!
In regards to dino, one could also use transtect as a soil drench, correct? I know with magnolia scale I’ll do a drench and spray a insecticide is crawlers are present

JD3000 · Feb 9, 2019

Correct

ATH · Feb 9, 2019

Acerxharlowii said:

Yes you can use it as a soil drench - because of that I don't worry about doing a bark spray if there is a little rain in the near forecast. Worst case with a light/moderate rain is it gets washed down the trunk and turns into a soil application. More significant rain I'd hold off because it is so water soluble, you don't want it washing away altogether.

I've had better luck with Imidacloprid on Magnolia scale...