Is this anthracnose on my Japanese maple?

April 21, 2013 4:18 PM

What is eating my acer palmatum?

Last fall, I bought a ratty bloodgood Japanese maple and planted it. This was to replace a Japanese maple sapling that succumbed to tan spots the previous year. Well, now the new sapling has leafed out and despite my attempts at hygiene cleaning leaf litter and applying a microbial fungicide during bud break, I now see tan spots on the leaves. Pics: hereIs this anthracnose? If not, what is it? What's the best treatment? Thanks green thumbs on the green!

posted by reverend cuttle to Home & Garden (2 answers total)

Best answer: Maybe? It's really hard to tell from that photo. Could be another fungal disease or mechanical damage. Fungal sprays during bud break need to happen regularly (every 10-14 days), but if it's been wet and rainy where you are it's really hard to prevent airborne spores from landing and spreading. At any rate, there's nothing you can do this season except avoid fertilizing and overhead water. Anthracnose hardly ever kills trees,though- are you certain that's what killed your last tree? Something else may call for different treatment.
posted by oneirodynia at 5:25 PM on April 21, 2013

Best answer: Meant to say, avoid fertilizing right now. Fertilize in mid-summer (if needed, according to soil testing) when there's not much active growth. If you get a lot of leaf drop in late spring or early summer (as sometimes happens with anthracnose, if it is severe), you can fertilize after the tree leafs out for the second time. However only fertilize if a soil test calls for it. Excess nitrogen encourages pests and pathogens.
posted by oneirodynia at 5:33 PM on April 21, 2013