Sulfur sprays: How often?

My apple leaves are growing fast with the days in the upper 60’s and 70’s. I’ve gone from 1/4" to 1/2" green to tight cluster on several varieties in the past couple of days.

Rain is in the forecast. My question is:

Should I consider making another application of sulfur before the rain for scab prevention?
Last time I sprayed was two days ago, and we just got a little bit of rain (~0.03 in). It seems like another spray would be overdoing it, as we haven’t had much rain. What does everyone suggest?

I was told by one orchardist that he doesn’t use sulfur, rather copper is his fungicide. Who recommends sulfur and do you add anything to wettable sulfur like neem oil, liquid kelp, etc.

Don’t mix sulfur and oil together so no neem oil. Usually its just sulfur a surfactant and water. Some people add copper also but you increase toxicity concerns.

You definitely do not want to mix oil and sulfur, it’s against labels. At least the one I have…

I think the other benefit (I think!) of sulfur is usage in-season, whereas copper is usually not sprayed unless dormant up to certain bud stage.

With sulfur, spray every ten days. Use a sticker. Every tenth of an inch reduces protection. One inch of rain basically means you are back to zero, so if you are getting lots if rain you would have to reapply every few days. Do apply prior to large rainfalls and then reapply afterwards. Use micronized sulfur.

Good info, but this is a big-time Zombie thread! :zombie: Haha.

1 Like