What do you use on Rhizosphaera?


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Has anybody played around with options enough to feel that you can say one product is definitively better than others?

Spruce trees are just coming out up here, so I've done round 1. I have been using Chlorothalonil, but that label switched from signal word "Caution" to "Warning". I try to avoid that if possible...both for applicator health, but also I prefer to explain to clients who ask about how toxic something I am using the 3 signal words found on products and that the one I am using is the lowest of those 3... Can't do that with Chlorothalonil any longer. I also like to switch fungicides to avoid building a resistant population.

I do see some recommendations on some Extension factsheets for Thiophanate-methyl. That still has a "caution label" (but when you put the 2 together, you get a "Warning" signal word...).

Open to other suggestions.



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Prune at ankle height and blame landscapers, deaigners, garden centers, and landscape architects.

T-methyl buzz has been a strong tendency towards disease resistance of late. Copper is still effective but your residual can be sketchy with lots of rain. I'm not aware if any Triazoles with the labeling, perhaps a Strobi?
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I've heard, thanks for chiming in!

I was trying to avoid switching from a "Caution" to a "Warning" signal word. I certainly don't want to make the jump to "Danger".

I think I'm going to use Tourney this spring - alternating with either a "Caution" labeled Chlorothalonil or 3336. Tourney is labeled for rhizosphaera, and I've heard it is effective.