To control what, exactly?

Baking Soda, Sodium bicarbonate, has been found to be effective at controlling some fungal growths. The link below summerizes many observations. In some cases Potassium bicarbonate has been found to be more effective. Many of us have used Baking Soda for Black Spot on roses and Powderey Mildew on many plants for years.

Here is a link that might be useful: Baking Soda as a fungicide

Yes, I'd like to know what your apple trees are having a problem with, too.

Me three.

Dan

My 3 year old apple trees get scab, black spot, white mildew (I guess) It is rainy here and lots of fungus. I've never sprayed, so trying to learn what to use.

Tons of references out there, most states' Extension Programs have an IPM program . Follow them.

You must learn the disease cycle(s) first so you know what to do when. You must also know the botany of your plants to understand how to address their issues.

Dan

You never sprayed yet. Three years have gone by and you appear to be unaware of even the simple growing instructions that came with your apple trees. You have already missed three or four important sprays called for by every spray schedule for apples that I have seen. Once passed over the damage that those sprays would have largely prevented is already done for this year. Someone has to almost see the mess your trees have been permitted to be get into in order to possibly save further damage.

I think your needs should be answered by your local nursery, your local farm agent or even a local garden club member whom you would surely meet at the first meeting. These folks would surely know your area and spray schedules commonly used.

Since there are scores of varieties of apples that are resistant to both apple scab and powdery mildew, that would have been the first road to travel - select those varieties suitable to your climate AND disease resistant.

Much of scab's ability to infect trees has to do with sanitation. Removing and destroying all the fallen leaves and fruit each season will help. As will dormant spraying with a Bordeaux or copper solution - both considered organic controls. There is some evidence that bicarbonate treatments are effective against this disease, but potassium bicarbonate has been shown to be more effective than sodium bicarbonate (baking soda). And FWIW, the 'black spot' is simply a leaf symptom of scab, not a separate problem.

White or powdery mildew is pretty much a cosmetic problem with larger woodies like apples, although a severe infestation can debilitate the tree and cause russetting on the fruit. Again, this can be addressed through sanitation and dormant sprays. And affected new growth (terminal shoots) can be pruned out. There are various organic controls for this as well - neem oil, bicarbonates (potassium again more effective than sodium) and targeted bacterial strains (tradenames 'Serenade MAX' and 'Sonata').

No one around here to help. No fruit growing clubs. Just Lowes and a couple or small nurseries that don't know much.

Yes, wish I had bought all disease resistant apples but didn't know anything about it back then. Great link about the apples in OH. Thanks.