AusBonsai

In the past week or so i have noticed the leaves on my Maples starting to turn brown and what looks to be damage from catipillers but i can not find any bugs on the plants. Can anyone identify what this problem is

japanese maples have a very tender leaf, this could be a wind/sun burn problem, i dont think it is the catapillars causing the browning they leave munching marks.

I recently noticed some black patches on my Amur maple. I thought they where drip stains from undissolved humic acid at the bottom of the watering can. (that stuff is tar black)
But that was not the case when they slowly got bigger and some leaves even had dead patches. WTF??? Seems like it must be a fungus. It is healthy enough so I am just hoping it goes dormant before it becomes a problem.
Looking at your picture I can see some black at the beginning of the leaf and on leaves in the background so I am guessing yours is the same issue.

You could try some fungicide but as long as the tree is healthy enough at the moment maybe waiting for dormancy before treating with Dormant oil and or lime sulfur through the winter will solve it.

Bretts

that sound like it could be he problem. With all the rain we have had over the past few weeks i spent the a day cleaning the mould that is growing on my driveway and around the shed on Wed. With all the mould around its more than likely fungus is growing to.

Thanks Andrew

Been no rain here for a while?? I hate fungus I will be covering everything in dormant oil this winter I might even move house
Walking down through town yesterday I noticed a couple of Chinese tallow's where covered in scale and had been treated with some type of oil.
Then getting back in the car I noticed an Ash had severe leaf curl which is similar to the other fungus I am fighting. Stuff seems everywhere lately

Mate you can have some of my rain it has not stopped for 8 days. On sunday i put a 5000 Lt water tank behind my shed and Mon morning it was full. Today we have only had a few showers

I hope the sun will shine soon i am over the rain for a little bit anyway

I would say this was anthracnose, just my opinion though. Remove the leaf, its stuffed anyway. Watch any soft tips and stems for rot. Remove them when spotted because the rot can travel all the way to the trunk once in.

Paul

New there was a photo somewhere. This is what it look likes when it attacks soft stems.
Paul

That was one of the names I have been looking at Paul. Sounds pretty close too all my issues this year. I would love to give it a definate name though.
http://www.na.fs.fed.us/spfo/pubs/fidls ... idl-ae.htm

This is probably what is going on at the moment.

On some species, the fungi in the infected areas of new leaves produce secondary spores, called summer spores. Wind and splashing rain spread the summer spores from leaf to leaf. The rapid increase of anthracnose in the summer and early fall is caused by these summer spores. Summer spores are common on ash and walnut.

Oh and removing the worst affected leaves would be ok but be carefull because toat defoliation can reduce the energy of the tree to fight the disease.

This might be informative. Many fungi causes anthracnose, it's a general name for a disease.

“The causal fungi of anthracnose on maple are found in the genera Discella, Discula, Monostichella, and Kabatiella. Leaf blight, caused by the fungus Kabatiella, often results in early defoliation of Japanese maple. Fruiting bodies (acervuli) of the causal fungi may appear on either the upper or lower surface of the leaves.” http://www.aces.edu/pubs/docs/A/ANR-1049/ANR-1049.pdf . If an extension lab is not readily available, a 20X lens is recommended for observations of leaves, if one is interested in looking for things such as fungal fruiting bodies, which are telltale signs. Several publications describe mature leaves as being more resistant to anthracnose, and many describe the brown areas as eventually curling, as we see in both sets of photographs.

Wet weather certainly sets of anthracnose, but it needs a entry portal, leaf damage due to sun, salts, wind etc lets it in. I often find it starts at the tips of leaves or on the edges of the leaf, rarely in the middle of the leaf. Poor nutrition also sets up the plant for attack. Lack of calcium, potassium and excessive nitrogen most notably.

Here's a picture of maple leaf with fungal hyphae on the underside. Note the tan color of the rotter.
Paul

Thanks Bretts and Paul

I will remove just the affected leaves and soon enough winter will be here and all the leaves will come off anyway.

I might get up early in the morning and contact my extension lab. Don Burke. Dumb bugger told me it was a pest a year ago

Make sure you have a good clean up through Winter Andrew. I am looking for the most non-toxic winter spring treatment that I can go berserk with. Saturation fire till the bugger is dead dead dead

Because I live in Qld i keep my maple separate from my other trees due to the heat so hopefully this will not spread to the others. I do agree a good clean of the area is long over due.