Question about fungicides for pines(or other trees)


Question about Fungicides for pines (or other trees)

Bonsai tonight community,

I have experience using Daconil, i would spray my pines every two weeks. I would spray my pines as the sun went down ( to prevent damage from sunlight etc) I would go cover the pot, soil and roots the best i could because I wasnt sure if the fungicide Daconil would hurt the roots, tree or mycorrhiza. No matter how good of a cover i would make, a little would obviously run down the trunk.

My understanding of the use of daconil is for the prevention of fungal diseases etc.

My question for you guys are,

Do you know if Daconil will hurt the tree, its roots or the mycorrhiza if it gets intocthe soil/root system?

I recently started hearing about zerotol and benomyl.

Any experience using either of these products?

Do you have any experience using other fungicides?

(Jonas Dupuich) #2

My advice for Daconil applies to all fungicides and pesticides - follow the instructions on the label to avoid surprises.

I’ve had good success using Daconil to treat needle cast on pines, and no damage was done to the trees. It was one of a number of fungicides I used in rotation to address the cast.

Using Daconil in combination with other chemicals, or at shorter intervals and in greater concentrations than those indicated on the label, can harm bonsai.

(Les Lonsdale) #3

The part of H.B.520’s question about will the fungicides hurt the mycorrhiza (sp?) was not addressed. I have had the same question in my mind for years. Should fungicides be kept away from the soil at all costs so they won’t kill the beneficial fungus?? Would this apply to other trees other than pines??

Thank you for any responses,

(Jonas Dupuich) #4

Thanks Les - forgot to mention that I have no idea about whether or not there’s any effect on mycorrhiza. In general I don’t do anything with the intention of promoting or inhibiting mycorrhiza in my trees.


In this link they talk about applying a mix of daconil and insecticide to bonsai in japan, it doesnt look lile they are very concerned about drenching the soil with it.



Just to clarify your response, by “With the intention of promoting” are you saying you dont use products like mycorrhiza spores in your soil?

In terms of the inention of inhibiting the mycorrhiza, do you spray fungicide that could effect the mycorrhiza but consider controlling the bad fungus more important?


(Jonas Dupuich) #7

Simply put, I don’t make bonsai care decisions based on whether or not they might have an effect on mycorrhiza. I may or may not be doing something that is good - or bad - for mycorrhizal growth, but as I’m not measuring this I don’t know one way or the other.

On occasion I’ve used fertilizers with different mycorrhizae such as Dr. Earth Life pellets and E.B. Stone products as I try different fertilizers on a regular basis, but I have yet to look at the effect the mycorrhiza may or may not be making.

(james phelan) #8

i also have questions about the use of fungicides, specifically the difference between systemic applications and applying as a spray. any clarity would be greatly appreciated.

(Jonas Dupuich) #9

Here’s a primer on different ways of classifying fungicides:

The basic difference between contact and systemic is that contacts only kill what they touch, whereas systemics get into the tree and make it harder for the fungus to hake hold. Both can be harmful if not used properly (reading the label does the trick). Also common to both - they only kill the kinds of fungus listed on the label.

(dave) #10

so no systemic fungicide for tree that dont have any sign of fungal disease?
better use contact fungicide and insecticide first for a precaution?

thank you

(Jonas Dupuich) #11

@dave - the answer depends on where you live. If fungus isn’t a problem where you live there’s no reason to spray without indications of a problem.

If you live in a place where fungal infection is a big problem, regular treatments can help. If this is the case, I’d check with growers in your area - bonsai or otherwise - about what specific pathogens cause problems locally and which treatments work best.