Hey, guys.
I’m new and unsure what is wrong with my amur maples.
Things had been going great and this forest really took off this spring. Now I am seeing some weird browning going on within some of the leaves. I did some googling and forum searching and it really looks like pictures showing anthracnose, but the environmental conditions don’t jive. It is hot and dry where I live. The tree gets a few hours of dappled shade starting in the mid afternoon. It doesn’t look like scorch either. Could it be not enough water? I water in the morning before work and check when I get home. I usually don’t water in the evening unless it was hot and windy all day. Soil is 1:1:1 and planting is 5 amurs in an oval pot about 12" across longest dimension.
I find the hardest part of this hobby is identifying why something is happening, so that I can make the right corrections. Thanks for helping.
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Leaf scorch? You may be getting too much heat for the amount of water you can supply. My deciduous trees like obscene amounts of water right now and I live in a much more humid climate using 100% diatomaceous earth. Do you have a pic of the entire tree? It looks like you did some partial defoliation and you may have opened up some exposure to softer interior growth. That would make them more susceptible to burn and explain why some leaves are still hydrated.
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@Casteel I can add more pics when I get home. I did defoliate because my inner leaves were not getting sunlight this spring. Thanks for the reply.
Your welcome. And I could be totally way off base. Dehydration was my best guess based on your climate, time of year and my limited experience with keeping deciduous trees alive in small, <12” pots. And the pictures. Some of the leaves look Dehydrated. I am sure other things can cause that but it would be easy to troubleshoot. Shade if you can and see how the young growth reacts.
@Casteel here are some more pictures. I think too little water is probably right. The pot surface was pretty dry when I got home. I picked it up and felt the bottom drain holes which I don’t normally do and it was definitely not wet. I really struggle with the understanding of the “balance of water and oxygen” that Ryan talks about. I can see the difference between wet and dry, but I can only see the top layer of the container. How far from totally wet from top to bottom to totally dry from top to bottom do you let the “see saw” go for your maples?
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How many times do you water the tree each time you water? One approach is to water it 3 times a couple of minutes apart. The first time wets the surface and edges, the second time wets most of the the soil, the third time fully wets the soil and makes sure all of the soil is fully hydrated. If you have a good draining mix, the excess water will drain out shortly and and tree will have a good supply of water for several hours.
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Hi Reno, the Amur maple comes from the base of mountains in Japan and as such they prefer cooler conditions. In Japan they keep them under shade during the summer.
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@MartyWeiser I water slowly using a shower wand and moving around the whole pot in an on and off fashion until I get water coming out the bottom about as equally as going in the top. I like your approach as an alternative. I can only water before work and when I get home at the moment. I will supplement with other methods when I can. Thank you for the reply.
@Keith-in-UK thank you for the reply and the knowledge. I think my weekend project is some sort of shade structure as I have south facing benches. I have been following a thread in the toolbox section for ideas.
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Nice group. It looks healthy. You may have just cooked some previously shaded leaves. Could that account for most of the damage you are seeing? I do not let the surface soil totally dehydrate. I use the soil particle color as a gauge. The DE goes from dark brown and shiny when it is wet to lighter brown/ grey and pale bone white when it is totally dehydrated. Wet
I water at this point.
This is about as far as I go towards the dry side.
Thank you. Also thank you for the pictures. That really helps. I think water is definitely the problem. Here is what my soil looks like when I get home compared to after watering.
It looks like you probably have a fairly free draining mix, It is easy to keep enough oxygen in such a mix. The issue is the water when it is hot and sunny. Do you water in the morning as well? That might help.
You could also put more sphagnum moss on to help retain moisture
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I water in the morning before I go to work. I recheck when I get home.
Hi Reno, I think your maples are scorched from too much sun and wind. I live about 200 miles south of you and used to have an amur maple. I kept it under shade cloth (50%) and watered twice a day about 12 hrs. apart. It did very well. Hot winds can burn leaves in just a few hours sometimes the plants just can’t pull enough water up to cool the leaves even if the potting medium is saturated. When the temperature gets above 90 most temperate plants like maples close their stomates to conserve water but it looks to me like you had a windy day that was less than 90 so stomates stayed open leaking water and the plumbing just couldn’t keep up with the demand. The tree will recover just fine.
Thanks for the information. There is so much I have yet to learn.
