> > The influx is far from uniform


My numbers support the same thing. Here are some wash numbers I did on 10/8 from colonies next to each other in a yard with 27 colonies all of which are in close proximity.    18, 9, 34, 16, 28, 15, 35, 29, 6 

In this yard, I applied OAV many times throughout the season at various intervals using a ProVap 110. This is my first year using the ProVap, and with these disappointing late-season numbers, I started to think about the efficacy. 

I begin vaporization dispersion tests by using different devices and examining the amount of vapor in the colony immediately following applications. Although I expected a cloud when I opened the top, most colonies just had wispy trails in the seams leaving me to wonder where it all went. To find out, I tried some with just inner covers and screened bee escape holes.  On those tests, very little vapor found its way out of the top - I expected vapor to pour out during the process.  It may be that to get the most out of vaporization in my field conditions,  learning more about how vapor is dispersed and how it condenses on hardware will help. Wind, humidity, and temperature may play a role in addition to the application point, and the configuration of the frame hardware. 

I'm not suggesting what I've done so far is science, I'm just questioning if what I'm doing is working and what kind of application method I need as a standard to get the most mite kill. For instance, on some colonies, I was sliding my Varrox under a screened bottom in a tray and allowing the vapors to pass up through the cold screen first. In those applications, it seems like not as much vapor gets into the colony. In cases where the bees are up higher in the colony, the vapor travels past a lot of cold frame hardware before reaching bees and that must have an effect. Hardware irregularities allow vapors out of seams and other places in differing quantities depending on the hardware's age which must also affect the treatment. in general, there seems to be a slight difference in dispersion between screened and solid bottom boards simply because it's harder to contain vapor with a screened bottom even when it's blocked. The final thought is the speed and force under which the OA is sublimated. The ProVap unloads in about 30 seconds versus the Varrox which takes about 2 minutes 30 seconds. Yes, the ProVap is much easier to use but how does the high-speed forceful injection affect where the vapors go and how they penetrate the cluster versus the slow warming and gentle release with Varrox type devices. I've got more questions than answers right now but hope to figure some of this out before next season. 


Bill Hesbach
Cheshire CT


  

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