Using Bordeaux mix

I have obtained some Bordeaux mix for some of my pines. Am I correct in assuming that it is to be sprayed on the soil as well as the foliage ? I know Daconil is generally not to be sprayed or applied to soil. Any advice on this.

I haven’t tried applying fungicides to the soil. It makes some sense for crops growing in the ground, but I don’t know that it’s a helpful approach for bonsai. Will be curious if anyone has experience with this, otherwise I’d avoid getting it in the soil.

Bjorn mentioned he uses 1tbs Daconil per 1gal water to water/soak the soil in spring (he got the tip from that other famous Italian? bonsai professional). He says it gets rid of disease/fungus that has accumulated over the winter and trees look much better.

Interesting - if trees look better after treatment the assumption would be that the trees normally suffer from low levels of fungus but not enough that they show more obvious symptoms. I don’t know if that’s a thing or not, but if the treatment does help, that’s an easy way to go!


He did also mention that this treatment is more suited/beneficial to climates where there are no deep, long, winter freezes… freezing winters which usually kill off bad bacteria, funguses, diseases, etc. in soil.

Tennessee (where he is), Italy (where Mauro Stemberger is, and also where this tip came from iirc), and probably SoCal, Florida, Southwestern/eastern US will probably benefit the most, since most of us don’t get long freezing winters.

1 Like

was Bjorn using this treatment for ALL types of trees? would it kill good fungus like mycorrhizae?

1 Like

I think so… he talks about it in one of his long YT podcasts, at the very end, the last 5 mins.

Mycorrhizae isn’t typically affected by fungicides. There’s a brief reference to this here:

and here:

1 Like

I live in coastal South Carolina, hot, humid and fungus heaven! Since I moved here I have had to start doing preventative treatments for fungus! I got advice from Zach Smith to do it in late summer & spring to attempt to keep them at bay! I only treat species they are particularly susceptible, try to never treat my pines, as mychroriza can be severely impacted from what I have researched. I use a granular systemic fungicide for this preventative.

Do let us know if you can identify research that shows both damage to mycorrhizae in pines and adverse symptoms in the trees as a result of knocking down the mycorrhizal population (pines can be healthy with no visible signs of mycorrhizae in the soil).

Certainly will update as I get more info. Spring 2021 will bring this experiment in controlling/reducing fungal load to a full year since starting the procedure!
I have a dozen red pines that will moved to colanders in spring so they will be an excellent gauge on what’s happening.

1 Like