Japanese maple care and recovery......... covering my bases

Ok so I have a small collection of japanese maples I have been either growing from seed or from grafts over the last few years. All are in larger nursery pots or modified nursery pots adequate to the size of the tree for root/nabari development and growth for another few years at which time I hope to have some more grow out room and can plant them in the ground to develop further as bonsai or landscape trees. At this stage of growth I use a modified soil blend of organic potting soil, sand, perilite, vermiculite, decomposed granite to provide good drainage while still maintaining the moisture needed for growth in larger containers. Over the last 3 weeks, our neighborhood was stricken with a plague of aphids which quickly found my maples and did a number on the new growth. Through safe soap treatments and the addition of praying mantis and several thousand lady bugs to my garden I think I have gotten rid of or at least gotten the aphids under control, however all of my trees still seem to be barely hanging on, with new growth curling or turning black, brown spots on leaves. I stopped fertilizing a few weeks ago to help get rid of the aphids. I guess I am wondering when I should start to see some progress or if I should be concerned something else may be the problem as I seem to be loosing some leaves here and there on various trees?

1.What is the best fertilizer regime for japanese maples in containers? Have been using a j. maple balanced fertilizer at half strength for a few years, plus slow release blood and bone meal twice a year for the last few years with good results but everything you read seems to contradict itself so advice is welcome.

2. Could this be damage from over watering or aphid treating and not just the aphids?

3. Aside from not over watering, over feeding, under watering, letting them dry out, and providing some afternoon sun protection on hot days for the next few weeks is there anything else I can or should be doing to help in their recovery?

In case anyone asks bellow are the cultivars I am growing...

Trident maple
Bloodgood
Acer Robrum (not a japanese but also affected)
Acer Sagar nishiki
Garnet Maple- red laceleaf variety
Acer kiyohime
Acer Katsura- Butterfly
as well as several green japanese maples

If I had to guess, your leaf problems stem from using a soap treatment on the aphids -- especially if it was a home-made soap spray, and even more especially if you gave them repetitive treatments. Many maples react badly to soap sprays. Commercial soap sprays like Safers are a bit better, but the sodium or potassium salts of fatty acids, with strong alkali component found in soaps can raise hell on maple leaves. Worst affected are trident maples, but Japanese maples (and others) are susceptible, too.

As for fertilizers, you trees will not care and there is NO SUCH THING as a maple fertilizer (except perhaps in the fertile imagination of fertilizer marketers). Anything with NPK and especially trace elements will work just fine.

An ordinary insecticide listed for aphids is probably better for your trees than a soap concoction. Just follow the directions.
'Butterfly' is not particularly recommended for bonsai, but it is tough as nails. Plant it in the ground, give it room, and stand back. Only thing to remember, check it annually for reverted shoots & cut them off.
Iris

lol, I have actually been told both that soaps are better than other treatments, and that the sprays and other treatments are better, but after much debate it seemed both had their follies so I went with the soap, next year I will stock up on juvy lady bugs earlier in the season, plus utilize a better ant blocker around my garden. Thanks for the advice/info. The butterfly maple is most likely going to be a large container or landscape tree once we move and I have a permanent yard again, but we will see.

For many plants, soaps ARE the best option for aphids. Just not on maples.

Perhaps you need to rely less on what you are "told" and rely more on the literature.

Next year don't bother with the ladybugs and mantids; they're pretty hit or miss. Get a spray that contains pyrethrin (made from a Chrysanthemum extract).

Thanks Jim, unfortunately what I was "told" was also what I read lol, gotta love the internet. I think next time I will just come to you, and I will definitely try the spray next year.

I think next time I will just come to you,

That might not help every time.

Instead, buy either (or both) The Southern Living Garden Problem Solver (Oxmoor House pub.) or the Ortho Home Gardener's Problem Solver (Ortho books, pub). Both will help you identify virtually anything that attacks your trees -- disease or critter -- and provide solutions. The Ortho book -- naturally enough -- is a bit more oriented to chemistry as a solution. Each book probably will set you back $30 or so.

Two other great references are: Garden Insects of North America (Princeton Univ. Press) (probably $35 by now), and The Encyclopedia of Natural Insect and Disease Control (Rodale pub.) which may be out of print but is available from Amazon for under $10 -- a BARGAIN. Its info is more limited than either of the first two books.

Sweet! Thanks jim, that sounds like just what I need.