Texas Gardening: holly hocks, 0 by SteveIndy

SteveIndy wrote:
gljns,

You should post some pictures of your hollyhocks. As Lou stated it has been a very wet and cool year here for us. Hollyhocks are very susceptible to all kinds of fungal infections - I have had terrible infections exactly of the kind Lou decribed, with little "spore" looking spots on the leave with corresponding raised brown spots on the undersides of the leaves. Early treatment of your hollyhocks with an antifungal, as you can find to treat roses, just as they emerge from the ground, and repeat treatment a couple of weeks later , is the best prevention. Black spots also sound like fungus but hard to tell without visually identifying it. If you've been watering heavily, even though you haven't had much rain, you could still have fungus. Yu could cut off the affacted parts (even if that means cutting the whole stalk to the ground) and treat aggressively and your hollyhocks may rebound and still flower, though yout stalks will be smaller. I have had success doing that.

Here is an example of typical rust on the undferside of the leaf - the spots on the top of the leaf are not raised like this: