I purchased an acer palmatum orange dream about a month ago, and potted it into a new, bigger pot. Nothing major, no real disturbance of the root balls. The tree had some mild burn on the top leaves which the nursery suggested was from under watering. I've been watering it twice a week (I live in Palo Alto, CA, so it's pretty dry), and the tree has now developed these white spots. Further, more of the leaves seem to be turning brown at the tip. I'd think it was just the onset of fall, but they're turning straight to brown, not yellow or orange. Picture below. HELP! http://www.flickr.com/photos/ewwr1842/6210217314/
I think that looks like too much wet. Is it in full shade? Are you sure it is really free draining, so no water at all around the roots? Orange Dream often doesn't show much fall color, so that's not necessarily a worry. -E
I've been trying to make sure I'm watering appropriately, but short of unpotting and seeing if it's soaked, is there any way to check that it's draining properly? It's potted, and when I water it, it seems to drain well. I've been watering it about twice a week.
If it were mine, I wouldn't hesitate to pull it out of the pot and check the bottom a few hours after watering. Since it was just repotted, I don't think any harm is likely. Anyway it doesn't look radical, I don't think you've got a lot to worry about for now. -E
In a dry place like Palo Alto I would recommend watering a potted JM more often than twice a week. Every other day would be ideal for a reasonably free draining potting mix, for a very free draining mix you might need to water every day. The white spots look a little like powdery mildew, it favours plants with dry roots. I agree with Emery that for a newly purchased Orange Dream it does not look too bad, some strees is common for new plants. At this stage of the season you need the plant to be putting energy into growing under the ground, not above it, roots not leaves.
Hm... so one vote for too much water.... one vote for not enough. something of a coin toss, then. Here's a question that might help: how do I know when it's time to water more? The fellow at the nursery said I should stick my finger in the soil, which I've done, and i've been waiting until the soil about half an inch down is barely damp. Too little water? or a lurking drainage problem?
Well, Maf may be right in that powdery mildew does show up under dry conditions; here I see it with wet roots also, in fact a dwarf sycamore I'm watching developed it this year, too wet too shady. But could be too dry also. I wouldn't recommend any watering schedule, it depends too much on the soil. And for maples even nurseries get it wrong, frequently! Also on how much sun it's getting. Anyway and again, don't panic! You've got the entire winter to work out the problems... ;)
With Japanese maples the effects of roots that are too wet or too dry can often look the same. Either condition can compromise the transport of water and nutrients from the roots to the canopy. So there is a possibility it could be either. I suggested watering the container every two days because that is what I do here (in a cooler climate) when the weather is dry and warm, (with an adequately draining mix). It is correct that the watering schedule depends on the soil, what type of potting mix was used? Japanese maples like a free draining medium.
In a dry, hot place like Toulouse I water potted maples every day (except when it rains ;-)), a few seconds just to insure the topsoil/mulch remains moist. And, yes, Emery, dry hot weather can produce heavy mildew infestation as I have witnessed this year, not very pretty indeed. Gomero
