One of my hyds (forgot to look at the tag, it's either Amethyst or Brestenburg) has developed rust-colored circles on its leaves. I should preface by saying that DH refused to cover the hyds for the winter (never again!!) although all had cedar bark mulch mounded around the bases. Now I know that a lot of buds were lost from the weird warm winter-cold spring we had in the NE; however Nikko Blue, Blue Bird, and Preciosa have buds/are blooming. Everything else aside from this one with rust spots has healthy new growth even if the buds were lost. So what's the diagnosis (I'm thinking a fungus?), and what's the cure? Another detail - this hyd with the spots is between a patch of black-eyed Susans and some lavender. I trimmed back the BES to give the hyd room (I never realized how persistent these things are!). The lavender gets harvested when it blooms. Thanks in advance.
what's with my hyd?
Sounds like a leaf spot fungus, often those are caused if you use overhead watering and water splashes back up on the leaves. I think once you get the spots it's hard to get rid of them, best thing to do is if any leaves get really bad and fall off make sure you pick them up (and in the fall when it loses its leaves make sure you rake up all the infected leaves), and also be careful when you're watering not to splash water on the leaves or else the fungus will continue to spread. There are anti-fungal sprays, but when I've had problems with leaf spots I've never found them to be very effective. Usually that doesn't interfere with new growth and blooming to a significant extent though, all it does is make the leaves look a bit ugly. So since it sounds like this plant isn't growing/blooming I wonder if there's not something else going on--any chance you can post a picture?
Will try to post a pic later. Been very careful about the watering and not splashing, really have been letting rain do the watering. The anti-fungal I use these days is baking soda plus cinnamon oil (RosePharm), figured a shot of it couldn't hurt the hyd. It is Brestenburg, btw.
It's not necessarily your watering that's too blame--if there was some of the fungus around in the soil and it rains, that can splash water up on the leaves too. Of course that's harder to control then, but if you're not adding to the problem by splashing water yourself then hopefully the problem won't get much worse than it is.
Well I e-mailed the person I bought it from and he diagnosed it as likely Sudden Morning Sun Spotting, wherein the dew drops act as lenses, magnifying sunlight and causing little fried spots on the leaves. I did take a pic to post, I'm at work now, will post it later. There's no way for fungus to reach this hyd solely and not anything else in the garden through splashing.
Some types of fungus will only infect certain types of plants, and within any given type of plant, there are often cultivars that are more resistant to fungus than others. So it's very possible to have a fungus affect one plant but not others. Not saying that's necessarily it, it could very well be the sun spotting problem too but I wouldn't rule out fungus just because it's the only plant that has it.
I think the guy I bought it from might have an idea what it is. It's not the rust fungus - no spore depots on the underside.
I think he's right too, that doesn't look like fungus spots to me either.
At least the prognosis is good! As the sun moves and summer turns sultry (dewpoint goes up), problem should self-correct.