diagnosis for spot on leaves

I have a few coreopsis plants and about a 1 1/2 weeks ago the leaves developed black spots (about 1/2 inch round) with a white spot in the middle. Not only do the leaves have these spots, but it seems to have made the blooms either die as they open or not open at all.

Has anyone ever heard of this? or know what it is? Treatment? I read something about baking soda/water mixture on another post. Also read something about peroxide/water. But I just don't know...quite new at this.

It definitely sounds like some sort of fungus. Are you watering them overhead? A lot of times there is a little bit of fungus in the soil and if you use overhead watering, it can splash the fungus up onto the leaves and they can get infected. So I'd be careful not to splash the leaves when you water, and also I would water in the mornings rather than the evenings, that way the leaves won't stay wet overnight which is another way to encourage fungus. Some people have had good luck with baking soda to control fungus, otherwise you could buy a anti-fungal spray if that doesn't work. But honestly if you pull off some of the worst looking leaves and don't splash water on the leaves or let them be wet overnight the problem will probably clear up on its own.

I know this is probably not the right thing to do, but I am new to this site, and am unsure where to post this question.
When is the best time to divide stella 'd oro lillies? They blooming beautifully now, and I would like to divide at the right time. thank you.

Thanks, ecrane! I do remember about 2 weeks ago I watered late in the evening and it was VERY humid. At the time I thought to myself that it probably wasn't the best thing to do, but I did it anyway. And now I'm reaping what I sowed.

I think I'll try pulling off the worst leaves and see if it clears up on its own. If it doesn't I'll try the baking soda/water.

I've seen several of your answers on other threads. Very knowledgable and helpful. How long have you been gardening?

I bet that was it, having leaves stay wet overnight is a good way for fungus to take control. I can get away with doing the evening watering thing out here because we don't have much humidity, but in a humid climate that'll cause problems. But the good news is if you don't do that any more and you're careful about water splashing on the leaves then the problem should stop getting worse.

As for me--I've only been gardening seriously for about 3-4 years, before that I had a garden and I kept the plants alive by watering them and throwing some Miracle Gro on them every once in a while, but I never really thought about them much beyond that. Then when I moved to California there were all sorts of new plants that I could grow that I'd never been able to before, and so I got really into it and now it's become pretty much an obsession! Most of what I've learned has been stuff I've read here or in the hundreds of gardening books and magazines that I have, plus of course a lot of learning from my own mistakes!

lyjg47--you should really start a new thread with your question, if you go back to the main page that lists all the topics and scroll all the way down to the bottom, you'll see a place to start your own new thread/topic.

Milk is a natural fungicide also - I've used it on my plants if I get any fungi growing.
For me, it has the added benefit of souring and keeping critters from wanting to nibble due to the taste/smell. (I havn't noticed any lingering smell myself)

Hi lyjg47 I dont recognise the name,of your lily, I live in UK so we prob grow your lily but under a different name, as with all lilies, wait till the flowering season is over, let the greenery die down as this sends food back into the bulb, once that happens, you can lift and devide your bulbs, when you dig your new planting hole, I would add a little fertiliser and new compost mixed together, as the bulbs are still active, they are trying to store reserve food for the next seasons growth and flowers, try to lift as much soil as you can and gently tease the bulbs apart, TIP, if scales(BITS OF BULBS) fall away, put them in a small polythene bag in a little compost or sand, close the bag up and put in the refrigerator for a few weeks and they will sprout new roots, remove the little bulbills into a small pots, look after as for pot plant in a shaded place, and you will have flowering bulbs in a couple of years, OR put scales into potting compost, (POINTED end up) keep in shaded place for about 6 weeks and check to see if they have got little bulbs on them, when they do, pot up and new bulbs will grow from that, good cheep way to increase your lilies, or give away to friends, hope this helps you.
WeeNel.