Randy Oliver- Extended-Release Oxalic Acid Progress Report
Randy Oliver has made extensive research to find practical method combating varroa with longterm efficacy.
“For those of you in New Zealand who can legally make your own OA/gly towels, the formula that I plan to test next season is something between the 1:1 and 1:0.5 g OA: mL gly. The problem is, it requires 1½ Scott Shop towels to hold the 18-g dose of OA in a 1:1 solution, unless you make the towels dripping wet with glycerin. The other problem is that if you make up the towels with the towels still on the roll, they don’t absorb as much solution as they do if simply stacked up. But it’s handier in the field to simply unroll towels off a half roll one at a time.
I’d like to come up with an application method that requires only two towels (or other cellulose carrier) laid crossways across the top bars with a space between them for bee traffic. The main site of exposure is likely the top of the towel (perhaps the cellulose matrix could be placed on wax-coated thin cardboard for easier later removal. I’m wide open to suggestions for application methods that don’t require the insertion and removal of multiple strips (too much labor for the commercial beekeeper).
I spent part of today making up 4 different half-roll batches of Scott Shop towels, to see how they’d feel with each containing 9 g of OA, and 9 or less mL of glycerin (with or without water added). The best that I’ve come up with is:
Per half Scott Shop towel: 9 g OA dissolved into 7 mL of glycerin
The above recipe still makes a fairly sticky and oily-feeling towel, but they pull off the roll nicely once they’ve cooled. They’d likely be better if made with a more-absorbent towel type.
Update 1 Dec: After allowing the roll of towels to sit uncovered for a full day in a cool room, the texture changed completely! They are no longer sticky or oily feeling, and peel off nicely, leaving no noticeable residue on my fingers (wear gloves). This formulation may be a winner!
To make a roll of 55 towels, cut a roll of Scott towels in half crosswise. Fold the edge of the first towel under, since it is very hard to find later if you don’t. Put on safety glasses to protect your eyes from any splash. If you get any acid or solution on your hands, simply rinse off with warm water (there’s no rush–the acid works very slowly on your skin).
Place 505 g OA dihydrate crystals into a saucepan.
Add 400 mL glycerin.
Turn on the heat, and stir until the OA is nearly completely dissolved. At this point, the temperature should have risen to about 140°F (60°C). Turn the heat down to medium and continue to stir until completely dissolved. There’s no need to allow the temperature to get above 160°F (70°C), but you can allow it to climb to 170°F (76°C)–above that temperature a chemical reaction will take place and bubbles will form–avoid this.
Remove immediately from heat.
Warm the half roll of towels for 30 sec in the microwave (longer can cause fire). Place the roll upright in a pot, and slowly pour the hot solution round and round over the top of the roll, only as fast as the solution is absorbed into the end of the roll. It took me 4:40 minutes to make the pour. Any solution that spills over the side will wick up through the bottom of the roll.
After all solution is absorbed, you may wish to flip the roll end for end as it cools, for even saturation. Allow the roll to cool before attempting to peel off any towels.
Makes 55 half towels—enough to treat 27 hives.
Apply 2 half towels per hive, crosswise between the brood chambers—applies 18 g OA per hive. Apply at placement of honey supers. Do not expect to see appreciable mite reduction until 6-7 weeks.
This application method is not yet approved for use in the United States—I in no way promote any off-label application of any pesticide.