You shouldn't worry about it.
The Immunox is systemic, rain doesn't wash it off.
In my experience Triazicide lasts even with rain, especially with a sticker. We had a huge storm last night and my trees still smell like Triazicide.

I just saw a few aphids and some leaf spotting. All else looks very good. Maybe the best condition for this time of Season I've ever had. I want to thank every one for the Immunox and Triazicide suggestion. By the way, I lost many of the bagged fruits in the recent storm.
I'll wait till Saturday. Thank You.

Joebella,

Myk answered your question well, but your question is a common one. MSU has been doing a lot of research in this area. They are now coming out with some good information. Below is a link to the latest info.

When you look at the tables, they don't list household products, but Triazicide would fall under the pyrethroid category. Look at Asana for comparison.

Here is a link that might be useful: MSU rainfastness characteristics of insecticides

Thanks for posting that, Olpea. It's from my alma matter, good old Moo U (which actually was a poor excuse for a university from my perspective as a student, got a better education the second time at a local commuter college, but they're leaders in agricultural research).

Very helpful.

We had almost 2 inches of rain on Tuesday, and so far probably close to an inch today.

I'm planning on respraying everything this weekend. I sprayed Imidan, Triazicide Once and Done, and Captan last Sunday night. Since it looks like the Imidan and no doubt the Captan washed away, and since I just bought some Immunox at Lowe's, time to redo it all. Better safe than sorry.

And, aren't the first couple of sprays the most critical of all due to plum curculio. At least they seem to be for me.

Yea, both MSU and Cornell are a great fruit research universities. Of course for livestock, I'd have to vote for my old alma mater Kansas State.

I can sympathize on the rain. I applied a pyrethroid with an EBDC on Tues. Then yesterday we got 2" of rain, so I know there is nothing left on the trees with more rain in the forecast. Still, I'm going to wait till next week to reapply.

I suppose you are applying Imidan and Triazicide on different crops right? They are both such powerful insecticides, it would be redundant to apply them both on the same crop.

Because I can't possibly respray customer trees after rain I have hands on experience of never reapplying Imidan after rain in scores of orchards and limiting my applications to one at petal fall and one 10 to 14 days later regardless of weather (as long as I get at least an hour of good drying conditions after spraying). We usually have plenty of rain here between my applications. Springs tend to be wet.

Whatever the researchers say are the limits of organophosphates to rain resistance, after 20 years of anecdotal observation I am confident that it takes an awful lot of rain to eliminate the effectiveness of an application of Imidan. Failures to protect fruit adequately have been extremely rare in the scenario I describe. Up until recently I didn't even use a sticker.

I remember when we discussed this earlier someone brought some research to my attention that showed that Imidan can still offer adequate protection in most cases even after 50% wash off.

Hman,

I think that is more or less what MSU is saying. If you look closely at the tables, Imidan/Guthion seem to be at the top of the list in terms of materials that need not be reapplied. According to the chart, even 2" of rain is not enough to justify reapplication if the rain occurs soon after application.

Imidan is rain tough, has kickback activity, and fairly friendly to beneficials. As you well know, in spite of being invented more than 40 years ago, there is still nothing else on the market quite like it.

That said, I would mention, as you frequently do, pest control is very regional. Two sprays in NY will not have the same effect below the Mason/Dixon line.

Sorry, I think I better go back and read the graft again, I only skimmed it before, but I think my comments should still be useful to the beginners.

Of course the longer the growing season the more applications will be needed and regions and even backyards in the same region will have varying degrees of pest pressure.

For instance, I have a lot more pest pressure on sites where the sod is maintained as a meadow and infrequently mowed than where a "perfect" lawn is maintained under trees.

Black knot pressure varies from site to site with very little easy explanation. Heavy dew sites sheltered from wind make it harder to control brown rot.

I have no idea why I've yet to have a problem with apple fly maggot, even though it is a common pest in the Hudson Valley. This pest in itself would probably require 2 extra spray of Imidan.

I'm not sure if there is a connection, but on sites nearing commercial apple production, scab and CAR pressure seem a lot higher.

Hman,

Good info.

That reminds me, do you ever get any significant problems with catfacing from stink bugs, or do your clients care? They fly all season long here.

We have plenty of tarnished plant bug and stink bugs. I see the green stink bugs in my trees quite a bit and I'm sure they're in my clients trees as well. They make a mess of what would be unacceptable percentage of my Seckel and Asian pears if I was a commercial grower. I've decided to try to reduce the plantain weeds on the edge of my property as much as possible to keep stink bug pop. down.

Mostly the stink bugs damage Seckel pears of my clients but not enough of them to justify all the additional insecticide required to keep them at bay. TPB is mostly a problem where there's lots of broad leaf weeds in the near vicinity and they can be a problem with peaches, but I don't spray for them either (besides the 2 Imidan aps) as they don't do all that much damage.