The One Best Way to know when fungus is attacking your rose garden

Tips for Handling Fungus

by Sandy Swegel

We’ve had crazy amounts of rain this season and a sad consequence of this is plants are plagued with leaf diseases of every sort. Organic treatment of black spot and rust and powdery mildew usually starts with useless notes like air the plant out, provide adequate drainage, pick off diseased leaves. Daily rain means there is no extra air, there’s nowhere for the water to go, and if we picked off all the diseased leaves there’d be no leaves left to support the plant.

The One Big Secret to knowing if a fungus is about to move in on your plant? Look on the bottom side of the leaves. This works as well for pumpkins and squash as for roses.


Catching the Fungus in action was the most important part of keeping your plants healthy.

Now you have to Treat it Regularly.

There is no reversing fungus when it hits your plant…there’s just stopping it from spreading. If you know you have plants likely to get diseased, like roses in the rain, or squash plants in hot stressed conditions, walk by the plants from time to time and look at the underside of the leaves.


At our monthly Rose Society Meeting with collectively at least 200 years of rose growing experience, we did come up with things we think you can do to keep roses and other plants health during a high fungus year.

Number One was to feed your soil.

Everyone agreed that good soil with lots of nutrients and microbes made for plants that didn’t catch every fungus and disease floating in the air.

Number Two was pay attention and respond quickly. Nip it in the bud so to speak.
Watch the underside of the leaves. As soon as there is the sign of disease start treatment.

Some people use foliar sprays like baking soda or potassium salts. Others used buttermilk. (both of those treatments change pH.) Some are big on compost tea. Liquid kelp in a spray bottle is my go-to for most things.

The trick with sprays is to pull off the entirely diseased leaves and then start spraying on the underside of leaves, then on the top. The second secret for sprays is to repeat them every week. One time isn’t going to do it.

That’s it. The short version of our collective wisdom when it comes to a rainy season full of disease:
Have a potluck so everyone can commiserate with each other about their little natural disasters. Then get out there and make sure your soil is good and you stay vigilant.

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