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Using lime sulphur

Posted by James Smith 
Using lime sulphur
January 31, 2022 02:52PM
So here is my dilemma, I have too many trees for one old bugger to care for, yet I value having the trees for the privacy they provide. It appears my relationship with the pest control board is going to be a long-term romance. Therefore, I've been pondering the idea of how to keep the rows along the road as ornamentals without any fruit on them. I came across this article about using lime sulphur [cpg.treefruit.wsu.edu]

Does anybody have experience using it?

Washington Okanogan Valley
Zone 6b
Re: Using lime sulphur
January 31, 2022 07:32PM
This is an interesting situation to be in, James. You seem to have the perfect scenario for trialing a lot of the thinning methods that have been debated on this forum over the years. Obviously, you still don't want to do anything that will harm your trees, ie leaf-burning, but most of the grower concerns beyond that usually revolve around thinning too much fruit, and we tend to be very cautious about even experimenting with thinning methods. I nominate you for chief guinea pig!

We have never applied lime sulfur orchard wide for thinning purposes (too many different varieties to have a hope of getting timing right across the board). We have played with it in certain varieties, usually with smaller hand sprayers, so the rates were 1.5 gal lime sulfur q.s. 50 gal water or 0.75 gal lime sulfur q.s. 25 gal water or 1.5 qt lime sulfur q.s. 12.5 gal water. I see we applied 3 gal. in the 100 gal. airblast, as well, so looks like our rate was consistent. When applying any thinner by hand like this rather than airblast, whether you're applying baking soda, as discussed in an adjoining thread, or lime sulfur, we've found results to be sporadic with blossoms (and entire blossom clusters, so not ideal, as you're really targeting everything but the king bloom) variably showing zero damage, some damage, or total annihilation. If possible, I would definitely recommend applying with something like an airblast for consistency of application throughout the tree.

Blossoms are at different stages all over the trees, so growers typically spray thinners two or more times, depending on how serious you're trying to get about controlling your crop load. In your case, since you're actually hoping to wipe out all the fruit, you are probably going to have to spray in the neighborhood of three plus times. Also be aware that cloud cover and temperature play a role with the thinning effects of lime sulfur. Conventional growers are really starting to jump on the lime sulfur for thinning bandwagon, so you should be able to find a lot of general literature about this, in addition to what you've already come across.

In our situation, we've backed away from using lime sulfur unless absolutely necessary for sanitation purposes -- too many severe chemical burns and too much equipment corrosion. But with regards to thinning apps in particular, there's so much living, sensitive, and expensive stuff that we're spraying around bloomtime, trying to be mindful of, and counteract, the sanitizing effects of lime sulfur is just too much for us. We are favoring the baking soda approach instead, but have a way to go to figuring it out.

In your case, lime sulfur may be the heavy hitter that you need to efficiently dispense with your crop. A big reason we are applying so much living stuff around bloomtime is for the direct protection of our fruit crop (far too complicated to leave it at that, though, as among other things, we're targeting fireblight, as well).

Anyway, hope that helps, as you think more about how this would work in your orchard. We're by no means experts on thinning with lime sulfur, have just dabbled in it a handful of times. Seriously, you are in a great trialing position to add a ton of information to this overall thinning conversation!

Kordick Family Farm
Westfield, NC
Zone 7a

Edited 1 time(s). Last edit at 01/31/2022 07:33PM by Brittany Kordick.
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