Pete>I don't think there can be a recommended "optimum re-treatment interval" other than monitor and use if needed. Any methodology that substitutes >for monitoring is unsound...


I would add that monitoring when using OAV at intervals is a subject worth considering.  A pre-treatment wash followed by a post-treatment wash is the accepted way to determine efficacy. But an open question is when to do the post-treatment wash so you are actually measuring the results of your treatment and not some natural variation in phoretic mites. Meaning that during interval treatments, which can take weeks, brood numbers and other environmental factors can change affecting the phoretic population and therefore the wash numbers. I think I got in trouble this season by relying on low wash numbers, after interval treatments of OVA, only to find large mite populations at seasons end. 

Imho, we have come to accept that wash numbers are consistently reliable at revealing something about the total mite population. But this season, I've been reminded that exactly what they reveal is dependent entirely on variables that include things like the amount of brood, grooming traits, and hygienic behavior to name a few. Wash numbers require consideration of those variables along with the efficacy of treatments before one can accurately interpret the results. My mental note for this year is that at times wash numbers can be as unreliable as stickyboard drops and for the all same reasons. Like any tool, there's a measure of art that accompanies its use. 


Bill Hesbach
Cheshire CT.

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