Checking out Cotton Matrices for OAE

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The Materials to Take a look at


A Box Trial





Randy Oliver

First printed in ABJ January 2023


I proceed to search for advanced strategies for utility of extended-release oxalic acid (OAE), and idea that possibly there could be an reasonably priced, totally biodegradable all-cotton cloth that would possibly do the trick.

Chipboard (cardboard) strips paintings neatly for hung-over-the-frame utility of OAE, however it takes a large number of time to insert sufficient of them to score just right efficacy, plus they want to be repeated. I’ve already discovered that Swedish cellulose sponges paintings really well for best bar utility of OAE, however they’re kinda expensive. Cotton appeared promising in a few of my initial checking out closing season, so I made up our minds to apply up on absorbent cotton materials.


Having little familiarity with what varieties of cotton materials are to be had, I checked on-line, at cloth retail outlets, and in thrift stores. Many cotton materials additionally comprise polyester, however since such plastics don’t seem to be simply biodegradable, I caught with 100% cotton best.

I in the end got here up with 3 such materials to check (Determine 1) — terrycloth, sweatshirt fleece, and (on the advice of beekeeper who had used it effectively) cotton batting. I ordered a number of other battings for initial checking out, and located one (Pellon Wrap-N-Zap) that had sufficient fiber energy to carry in combination all over dealing with, was once 100% cotton, and really reasonably priced in bulk. I had excessive hopes that I’d discovered the perfect matrix!

Fig. 1 Finish perspectives of the 3 examined cotton matrices, in comparison to a Swedish sponge. I came upon that it is extremely tricky to discover a natural cotton sweatshirt cloth, so the one who I examined was once thinner than I’d was hoping for.


I lower 10 pads of every cloth, all to the similar dimensions as a part Swedish sponge, weighed them, after which saturated them on the identical time from a unmarried batch of heated oxalic-glycerin answer (Determine 2).

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Fig. 2 I lower the entire pads to compare the scale of Swedish sponges lower in part. After sitting in a single day, the batting pads (at backside) confirmed some irregularity of saturation on their surfaces, however their dealing with traits have been OK as soon as the oxalic crystallized.

I then reweighed the pads to decide the typical absorption of OA answer through every matrix, in order that I may just evaluate it to that of the sponges (Desk 1).


Desk 1 Absorption of oxalic-glycerin answer through the matrices. In comparison to the sponges, terrycloth held extra answer, the batting about the same quantity, however the sweatshirt cloth some distance much less.

I had in reality was hoping that the batting will be the dream matrix that I’ve been searching for: reasonable, biodegradable, no components. Sadly, I discovered that this batting was once to begin with immune to the absorption of water or glycerin (Determine 3).

Fig. 3 The cotton batting appeared supreme, till I dribbled it with water. Not like the Swedish sponges or terrycloth, which might be handled for fast absorption of water, the batting was once now not, and took considerably longer to wick up the heated oxalic-glycerin answer (strike one towards it).


We had a few yards of colonies in past due Would possibly with average to excessive mite counts, so we took beginning mite wash counts, and randomly assigned the other matrices, blocked through beginning mite rely (Determine 4).

Fig. 4 On 20 Would possibly we carried out the pads to double-deep medium-strength hives, replicated in two other yards (which grew to become out to be a just right resolution). Listed here are the pads laid out on best of the hives in Backyard D earlier than utility. We left the colonies on my own, and took ultimate mite counts on 25 July (66 days later).


As is regularly the case in box trials, we were given differing ends up in the 2 yards (which is why it’s at all times absolute best to copy trials). To our wonder, probably the most hives with the easiest beginning counts (28, 31, 42, 49, and 63 mites in step with part cup of bees) in Backyard D collapsed, similarly in all remedy teams.

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Sensible observe: In our earlier trials through which we carried out OAE remedies later within the season, they’ve at all times controlled to show even very excessive mite infestation charges round and save the colonies. Then again, the few instances that I’ve carried out OAE remedies to high-mite colonies within the springtime, a few of them have collapsed. I don’t know whether or not that implies the rest, in order they are saying, “Additional checking out is vital.”

Not one of the colonies collapsed in Backyard L, most likely as a result of they’d additionally began with decrease mite counts. However there have been different variations between the 2 yards:

  • The colonies in Backyard L had loved a just right nectar and pollen drift, and received weight. On the finish of the trial, the entire matrices appeared wet on their higher surfaces, and after a mild contact with my fingertip, I used to be in a position to style robust acidity. Once I positioned samples of the spent matrices into zipper lock luggage, there have been droplets of oxalic answer at the insides of the baggage.


  • In Backyard D, then again, the panorama appeared drier. There were little or no honey drift, the colonies have been vulnerable, and the surfaces of the entire matrices — as opposed to the sponges — weren’t taking a look wet. Once I touched them with a fingertip, I didn’t come across as a lot acidity. And after I positioned samples of spent matrices into zipper lock luggage, no droplets confirmed.

Sensible utility: The diversities within the appearances of the higher surfaces of the matrices within the two yards in reality stood out. The primary distinction between the yards that stood out was once that Backyard D was once drier and loved much less nectar drift, however I do not know why that may purpose there to be much less OA-glycerin answer at the higher surfaces of the matrices, since our assessments in earlier years had been run below very dry prerequisites. Why the cotton matrices would carry out otherwise than the Swedish sponges I don’t know.

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So far as mite discounts after the remedies, the yard-to-yard variations have been additionally considerable, and strongly correlated with how “dry” the matrices seemed. Mite keep an eye on was once just right for all matrices in Backyard L (Determine 5).

Fig. 5 Mite keep an eye on was once just right for all matrices in Backyard L. I didn’t run untreated controls, so can best display beginning (blue) and finishing (crimson) mite counts for every colony. There have been an identical mite discounts for all matrices: median discounts 92% for the cotton felt, and 84% for all 3 of the opposite remedies.

It was once a special tale in Backyard D (Determine 6).

Fig. 6 The median discounts for the surviving colonies weren’t just about as just right on this backyard, as indicated through the higher quantity of crimson appearing. Median mite counts if truth be told went up for the cotton batting, and the median discounts have been 21% for the felt and 38% for the terrycloth. The one matrix that labored neatly on this backyard was once the sponges, which exhibited a mean aid of 82%.


Those effects have been an ideal wonder to us. I dare now not strive to provide an explanation for why probably the most remedies failed in Backyard D, since later within the season, when prerequisites have been dry, OAE throughout the remainder of our operation (carried out on store towels adopted through Maximizer pads) equipped superb mite keep an eye on.

The sponges have been obviously the standout for luck (we didn’t come with Maximizers, which I believe would have carried out in a similar way). However the abject failure of the cotton matrices generally (and particularly the batting) in Backyard D have soured me on cotton materials.

I’ll proceed to check different reasonably priced matrices. When you’ve got had luck with a biodegradable matrix that doesn’t comprise questionable components (take a look at the product’s Subject material Protection Knowledge Sheet), please let me know.

I’m listening to sure comments on OAE from in every single place, and can quickly be writing extra about my analysis this previous season.

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