I have an apple tree in my yard that was planted last year, and its leaves have a number of yellow spots on them. These yellow spots that have slimy red-orange centers. Based on the pictures that I have seen, this looks a lot like Cedar-Apple rust.

I've looked for treatment options, and most places recommend something called Immunox, applied once every 10 days or so. However, these websites also mention that treatments should start when the tree blooms. My tree bloomed a long time ago, and I didn't see the spots until last week. Will applying the fungicide still work? Is there something else I should be doing?

Hi Lars, you might want to look over this website on cedar apple rust. http://urbanext.illinois.edu/focus/cedarapplerust.html the reason they have to be sprayed early is that the fungicides protect against infection. the cool wet of spring encourages disease generally later the weather is hotter and drier and not as conducive to disease infection. you might also look to see if you have any infected junipers/cedars in your yard. It's really too late to do much spraying on the apples. might also want to look at this fact sheet. http://www.aces.uiuc.edu/~vista/abstracts/a802.html Sandy

The fact sheet referred to in Sandra's response is no longer active. The focus on plants document at the urban text site doesn't give treatment options. These two options aren't very helpful.