What I spray has been heavily influenced by Low-Impact Spray Schedule (2019 Edition) and Spray Schedule- Synthetic Materials. My goals are to have as much edible (as opposed to pristine, sellable) fruit while doing as little damage as possible, without spending a fortune, recognizing that there isn’t 100% compatibility between those goals. Today I ran across some surprising information that has affected what I’ll spray this year. Sulfur is rated as more toxic than most synthetic fungicides. I spray copper for fireblight control. Today I found out that copper sulfate has been shown to be highly toxic to stingless bees, while other copper formulations haven’t. Of course there are all sorts of caveats to this-perhaps the others just haven’t been studied sufficiently. However, for now that leads me to use some other copper formulation rather than copper sulfate. I also use captan and propicanazole for brown rot control on stone fruit. Captan, it turns out, is potentially toxic to a bunch of different bees, in part due to the inert ingredients mixed with it. So now I’m looking for a Captan alternative.
Thanks that is a pretty interesting table. I was surprised about the sulfur data so went and look at the citation. It is only for ingestion in honeybees so the main problem would be getting sulfur on flowers. Some other studies showed very little impact so it depends on how much ingestion is happening. Also the amount of sulfur used (how many sprays) will matter as well.
Copper in general is not good long-term, it builds up in the soil. I only use copper if it is needed for something in particular; recently I have not needed much of it.
Captan also is well known to be bad for bees. I don’t use it myself.
Most of the modern synthetic disease control sprays come out pretty well, it is only in various (uncommon) interactions that they may be bad. I am currently using Elevate and Indar as my disease sprays. Overall this kind of data makes me more appreciate non-organic as opposed to organic disease controls in terms of lower impact.
Good point re: copper. Copper Sulfate (e.g. homemade Bordeaux mixture, mixing Bonide Copper with hydrated lime) is toxic to stingless bees, while Kocide (copper hydroxide) is not. I used to mix my own Bordeaux mixture, but have switched to Kocide.
And some organic standbys have some unfortunate effects:
horticultural oil (with thymol, menthol, rosemary)- highly toxic when bees stressed
neem - honeybee larval mortality
spinosad - bumblebee oral acute toxicity
True that elevate, indar, and ziram do not show bee toxicity in this study. I have never considered using these, but might change my mind!
Thanks for taking the time to dig deeper on the sulfur.
Copper has been my first choice for fireblight prevention, though I’ve used some antibiotics in the past, and may rely on them more heavily in the future. I just can’t get a handle on fireblight: as soon as I think I know which trees to get rid of, we get a year like last year with supposedly resistant varieties like Goldrush and Liberty suffering terribly, while 20 feet away a supposedly susceptible variety like Pink Lady has almost no problems.
The other thing that jumped out to me from the table was Spinosad being rated highly toxic. I knew it could be bad for bees, but not that bad. Based on that table I’m really going to limit it’s use, and make sure there’s nothing flowering beneath my trees when I spray it.
Good point, I neglected to look that up (spinosad is the only pesticide I use). I personally think it should be in the orange category overall, it is mostly oral toxicity. It is light-years from Imidan in terms of toxicity so grouping it with that is extremely misleading and makes me question the whole document somewhat. At least they should have made a fourth category for the really toxic stuff like Imidan.
I lack the expertise to evaluate the specifics of any toxicity conclusion. However, there are several things that strike me as marks of a good study:
comprehensiveness
sources (seemingly reliable ones) cited
no obvious biases (organics and synthetics ranked all over the place, no preference for newer products or traditional ones)
Specificity and nuance, such as the distinctions between different copper products, or the note about rosemary oil.
One aspect that I didn’t pick up on at first is the red, orange, and yellow categories are for honeybee impact only. That’s clearly stated above the table, but it’s not in the title to the table, so the title is somewhat misleading. The last column is the effects on other bees. My suspicion is that because of the vast number of products that could be used, the varying number of sprays per year in an IPM approach, and the huge number of species that could be impacted, is that there is a lot of room for additional studies.
That is a really nice and comprehensive document. Thanks!
I do have a few notes though.
The document seems to only/mainly care about (honey) bee’s. This might give a bad “total picture”, for example on copper. It saves up in the soil and can become toxic to worms/soil life (low concentration) and plants (high concentration) and practically stays there forever. Basically, that something hurts bee’s relatively little does not mean it is harmless on other aspects.
It color codes based on LD50 in micrograms of active ingredient per bee. This does not take into account the amount of active ingredient needed (efficiency).
Lets say for example ingredient X has a LD50 of 1.9μg (color coded red = worst category)
But is efficient at eliminating your pest, and thus your total needed dose is 1 grams of active ingredient. for your whole spray.
And ingredient Y has an LD50 of 14μg (yellow, practically non toxic category) but is not as efficient at eliminating your pest and thus you need 25 grams of active ingredient for your whole spray.
The ingredient Y will end up being more harmful.
If all of the active ingredient where to be ingested by bee’s of those X and Y spray’s.
X would kill 1/(1.9*1.0 × 10^-9)/2= 2.6 10^8 bees
Y would kill 25/(121.0 × 10^-9)/2=10 *10^8 bees (thus ~4 times as many!, while it’s classified as "practically non toxic vs highly toxic)
I might have missed something obvious here. But it does not seem to accounted for efficiency/concentration of active ingredient?
ideally you’d correct for needed active ingredient per surface area sprayed at label dose.(also taking into account needed sprays per year)
lastly it mentions but does not seem to account for the systematic or “only on contact” nature and half life of the pesticide.
There is a big difference between something that’s systematic with a long half live, compared to something that’s only on contact with a short half life. Or only damaging before dry.
I’ll look at the document again tomorrow. Maybe if overlooked something. But as it stands now, I’m not sure how “fair” the comparisons are within the document.
They are pretty clear about being focused on bees, but I agree @oscar that their groupings are somewhat arbitrary since different compounds are sprayed at different concentrations. This is related to my issue with how they seem to consider a bad oral ingestion result to be just as bad as an exterior exposure result.
They are certainly trying to be objective and make a clear quantifiable bar, but in the process they end up coming up with some misleading tables. My guess is they came up with the three column meaning in advance but didn’t re-think it after they had all the data in place and had time to step back and think about what it was conveying.
Here is another link that lists the toxicity of fungicides and other agriculture chemicals to adult honeybees and their young. It’s from the University of California.
My coworker has a saying above his desk. “There are three kinds of lies. Lies, Damn Lies, and Statistics”. This is a perfect example of statistics portraying a false pretense for something that should have been made easy for the end user to discern, yet as your exchange with @oscar shows it may have just made things worse. If you use critical thinking you can figure it out with some research and further math as Oscar did, but it shouldn’t be hard. The average person is going to look at this and come away with a poor understanding of what to use.
If you check Sulfur with this UC listing, you get green level III
" No bee precaution, except when required by the pesticide label or regulations."
Bordeaux, Lime Sulfur, and Copper Hydroxide are all level II "Do not apply or allow to drift to plants that are flowering including weeds, except when the application is made between sunset and midnight "
Hard to know what’s what.
@oscar that’s a great point about this document, and the University of California one from @mroot, both being focused solely on bee health, and not considering other potential negative impacts. The lethal dosage, spray concentration, and the oral ingestion vs. exterior contact criticisms from @oscar and @scottfsmith make sense to me. I wish someone who created these documents was on this forum and could respond to those criticisms. Though it’s hard not to take things personally, good researchers should take criticisms as opportunities for improvement or to clearly explain why they made the choices they made.
Knowing these documents are limited (primarily honeybees) and potentially flawed, I made a chart of the products I have used or intend to use this season which shows the impact ratings from both Cornell and University of California.
Product
University of Cal.
Cornell
Notes
Horticultural Oil
Moderate
Low
Copper Hydroxide
Moderate
Low
Streptomycin
Low
Low
Myclobutanil
Moderate
Low
Potential bad synergistic effects with multiple pesticides-UC. Don’t tank mix.
Propicanazole
Moderate
Low
“Toxic to other bee species”-UC. Lots of bad pesticide synergies, decreases bumble bee reproduction-Cornell.
Captan
Moderate
Low
“Toxic to other bee species”-UC “Highly toxic to mason bees and leafcutter bees,” inert ingredients also may be toxic-Cornell
Bacillus amyloliquefaciens (generic Serenade)
Low
Low
“Toxic to other bee species”-UC
Spinosad
Moderate
High
“Toxic to other bees”-UC “High contact toxicity” for 3 species and “moderate” for 2 others-Cornell
BT
Low
Low
Sticker/spreader
Not listed
Low
Zeta-Cypermethrin
High
High
“Toxic to other bees”-UC “Highly toxic to solitary bees” Probable bad synergy with propicanazole-Cornell-don’t mix.
I’ll be looking to make some changes based on what I’ve learned. Effective use of Surround would solve many of my concerns, but I’m not willing to commit to that regimen yet.
Thanks for that UC link. I think they did a much better job than Cornell in terms of taking the bigger picture and not being a slave to their data. I don’t find any of their ratings off.
My gripe is with Scotts-Ortho removing their Acetamiprid product from the market over Think of the bees! Part of the knock on neonics is the heavy use of Imidacloprid on corn, which is used systemically. Acetamiprid is not applied to the roots and it is known to be much less bee toxic than Imidacloprid, but once people get Neonic Bad into their heads, well, you get the idea.
Every last replacement for Acetamiprid is even more bee toxic.
I am in a region with heavy curculio and maggot fly presence and moderate codling moth. I tried the organic path of just putting up with blemished fruit, and most of the harvest ended up on the ground.
The Ortho Acetamiprid product meant that I could get usable, storable fruit from that orchard, but my supply of it is about to run out, and I have to think of something else.
I read label directions and won’t spray with the leaf petals out, but anything I decide on going forward is going to be more bee toxic.
I alternate, or use both in the same tank. They are of different classes so it will prevent resistance. I have gotten extremely good control of rot with this combo.
I used home made lime sulfur 10X dilution plus surfactant oil spray on all my peach trees and pear and apple trees in beginning of March. One week later alot of lateral branches and further more all of my peach flower buds were die. pear and apple trees are ok. I wonder if it because of the Oil added to lime sulfur, or I had used the lime sulfur are too concentrated. I did sprayed very thoroughly. Want to know what wrong with my spray to avoid the mistakes made in future.