Spray frequency vs . challenging weather question

marknmtMay 29, 2013

I need to be getting a spray on for CM and will be using Triazicide. I think there's a decent chance of my tree getting rained on as we've been getting sporadic afternoon showers.

The label limits you to five post-petal fall sprays/season. Is it legitimate to count two sprays as one if they occur "close enough" together? And what constitutes "close enough"? I am thinking of spraying on this coming Saturday and Tuesday.

Corollary question: how long can you allow mixed spray to stand in the sprayer before it begins to lose its efficacy?

Thanks,

Mark

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olpea(zone 6 KS)

"The label limits you to five post-petal fall sprays/season. Is it legitimate to count two sprays as one if they occur "close enough" together?"

Hi Mark,

Unfortunately the # of sprays per season on the label is for the total number of sprays (whether they're washed off or not). One of the factors the EPA considers in their methodology in determining maximum seasonal applications is leaching potential of the compound. They limit the number of applications to reduce leaching, so the max amount of a.i., or max number of applications per season is determined partly in order to limit the impact on the environment.

In terms of how long a spray solution remains potent in the tank depends largely on compound in question and the quality/pH of water.

Some compounds (like carbaryl and Imidan) are naturally unstable and break down fairly rapidly in the tank (especially if the pH is high- which is common with tap water). For compounds such as these it is generally recommended the water be buffered to lower the pH so that the water is slightly acidic.

I couldn't find anything definitive on Triazicide stability in water, but did find information on the stability of lamda-cyhalthrin, which is very close in chemistry to Triazicide. According to the fact sheet (see link below) lamda-cyhalthrin has a half-life of 7 days in alkaline water and is very stable in neutral or acidic water.

My inference is if you are using tap water and left Triazicide mixed in the tank for 3 or 4 days, you would still have 75% of the active ingredient you started with. If you could buffer the water to neutral or slightly acidic, you'd probably still have close to 100% active ingredient in the tank after 3 or 4 days.

Here is a link that might be useful: NPIC-Lamda-Cyhalthrin

    Bookmark   May 29, 2013 at 4:25PM
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marknmt

Much appreciated, Olpea. Thanks.

    Bookmark   May 30, 2013 at 7:34AM
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