Unhealthy A. circinatum seedlings

Greetings,

I have about 30 Acer circinatum seedlings that are about 3 mos. old and are exhibiting some unhealthy signs (see attached photo):

- curling of leaves
- discolouration of leaves
- white substance on leaves

I am new to gardening and hope to have a at least 5 of these survive to place in my yard - can some one please assist me to diagnose what is wrong?

I also have 5 Acer macrophyllum that I hope to plant in my yard and they are showing simillar signs.

Thanks,
Mike, Victoria

-----------------------

Some background:

Growing media = 1 gal container with equall amounts of potting soil w/Osmocote, SeaSoil, sphagnum moss peat and a bit of maple/oak leaf mulch

Watering 3-4x weekly about 1cm of water (initial watering after transplanting from smaller pots included soaking buckets in water to allow peat to moisten).

Fertilized with complete fertilizer weekly at 50% of rated amount.

Plants receive about 4-6 hours of direct sun each day and are in an area that has good wind/ventilation.

 

Leaf shape and color might indicate need to adjust nutrient regime and irrigation practices. White is foliage mildew, could imply a problem with drying of the root zone. Foliage mildews of susceptible kinds of plants (such as deciduous azaleas and certain roses) are prevalent on the Pacific Coast in mid-summer because the combination of dried-out soils and foggy weather (resulting in moist, but not heavily rinsed leaf surfaces) is perfect for them.

 

These photographs just don't look like A. circinatum to me. Are you sure that's what they are? Unless the leaves are curling under an awful lot. The leaves (as described in Kruckeberg's 'Gardening With Native Plants'): 'Its palmate leaves are symmetrically seven to nine-lobed, each lobe pointed and with a toothed margin" Also, that sounds like a lot of fertilizer for these wild ones. Osmocote *and* liquid fertilizer?

I transplanted a lot of seedlings last fall - but now they are leafing out & most are A. macrophyllum instead of A. circinatum! This fall I will pick seeds directly from my favorite trees.

I hope they recover & do well for you! Let us know what happens as they get older.

Wanda

 

Round leaves appear as plants get older. Sometimes young vine maples even look like Japanese maples, revealing their relationship.

 

Really? I have about 50 acres here, covered with a multitude of native plants - many of which are Acer circinatum & I've never seen round leaves on any of them at any stage of growth. I will have to start observing other stands of circinatum to see if there are deviations from the ones I know here. Would the fertilizer being used have any bearing on the size & shape of leaves?

Wanda

 

Are you sure these are Acer circinatum ?

Leaves should look like this

 

What I was saying was that youngsters sometimes have non-rounded leaves. occasionally quite like those of Japanese maple, before they go on to produce the familiar shape. This can be seen in the stock shown in the original post here, I was mentioning that it was normal.

 

I guess I should be more specific in which/where Acer circinatum I am talking about. I live in the foothills of the Cascade Mountain range in Oregon. The Acer circinatum I am referring to is not a named variety but the native species. And yes, Andre, I'm sure that's what they are.

There is a reference to the Acer circinatum in the Vertrees 1978 edition - I haven't checked the 3rd edition. Mr. Vertrees gives an excellent description of our "Vine Maple". When I first became interested in the Acer palmatum I was surprised to see the similarities with the Acer circinatum. And in reading of using circinatum as root stock - really surprised. It really is a small world, isn't it?

Here is a USDA link with all the info:
http://plants.usda.gov/cgi_bin/topics.cgi?earl=plant_profile.cgi&symbol=ACCI

Wanda

 

Can you post a picture of your circinatum leaves ?

It should form a round as you can see here : http://www.nwplants.com/plants/trees/aceraceae/acer_circinatum/

 

My guess is that you both mean round as in palmatum shaped? I went out in the woods today & took a few photos of my circinatum - both old (over 40 years at least) and new (seedlings). Here is a photo of the really old one and a photo of another younger one in the woods.

 

And here is a photo of 2 seedlings in the woods. The one on the left is Acer circinatum, and the seedling on the right is Acer macrophylla. There seems to be a lot of seedlings this year, probably due to the relatively warm winter & the lack of sheep in this particular part of the pasture. Most have slug & insect damage - and apparently the deer haven't found them yet. The second picture is of an Acer macrophylla.

Wanda

 

Well, I'm glad to see that my original posting regarding the health of the seedlings has generated such great interest!

To answer a few questions: Yes, I'm sure the plants are A. circinatum, attached is a photo of parent plant located on the campus of U of Victoria. Also attached is recent photo showing developing leaves of my seedlings which are showing a more characteristic "Vine Maple" shape. As I read in another disussion/posting in this "Maples" forum it can take time for seedlings to take their true form. I have A. macrophyllum seedlings and they are distinctly different - bigger/rougher/thicker cotyledons, petioles are more red in colour, leaves are thinner and more "squarley" shaped (for lack of better word). I do not feel the identity is an issue for me as the parent is known and the seeds' path from harvest to potting up was well documented.

Regarding Osmocote use - it was added when the seedlings were in small 4" pots. They were pricked out of a tray and added to a sand/fir bark mix with roughly 1/2 teaspoon per pot. Seedlings were later potted up into 1 gals but additional Osmocote was added. I felt it neccessary to use some fertilizer as I believe these seedlings are growing in media with limited nutrients - peat/seasoil/sand/leaf mulch.

I agree with Ron B. who felt this was an issue of "nutrient regime and irrigation practices." So with that in mind I:

1. reduced watering to once per week and fertilization (with 50% dilute 20-20-20) is every second week.
2. moved the seedlings to the west side of my property where they receive about 2-3 hours of direct sunlight and late afternoon filtered sunlight.
3. Mildew issue - I found another UBC posting that referenced a web site recommending a spray of water diluted skim milk (10:1). I sprayed all leaf surfaces - mildew has cleared but not disappeared.

Some newly developing leaves are still curling under but the discolouration is less pronounced and the appearence of "veins" and leaf edge discoluration is also less. Most seedlings are 6-8" high on average - some taller and some smaller.

Maybe less fertilizer is required as the plants age? Does anyone have an opinion on the use of fertilizer with seedlings?

It's great that this forum exists to help us all and I really appreciate the effort all of you have made to aid me! Thank you very much - my seedlings are improving and I appreciate your help.

Michael.

 

I have concerns about your potting mix. I discourage the use of peat moss in maple potting soils because it holds too much water. I use composted pine bark as the major component in the mix. Make sure that the mix drains well. If the pot is very heavy after you water it is not draining well enough. Maple roots need plenty of air and will rot if kept too wet.

Use a well draining mix and you can water every day if you want.

Dale

 

Thank you for the tip - I wish I had heard that sooner ... do you think I could get away with potting them up into 2gals at the end of this summer using a mixture with no peat? I realise that might create a potting mix with different density layers but might it help them to prosper next year?

I guess another option might be to repot them now - but I am afraid the stress would do more harm?

Thanks,
Mike

 

Repot when roots are approaching bottoms/walls of containers. You want to catch them before roots are diverted by pot walls. This can happen rather quickly, much stock sold is rootbound because it was not potted on nearly often enough.

 

You want to catch them before roots are diverted by
pot walls.

In our nursery that is exactly what we did want. We
wanted the roots to grow outwards then down the can.
That way we limit the amount of swirling roots which
will lead to a pot bound condition if not caught in time.

With added time release fertilizer in the soil mix and then
with additional applied Nitrogen I am no so sure we are
looking at good root development as it is. We never
added Nitrogen to our soil mixes for seedlings. We
waited to fertilize any of our seedlings with Nitrogen
until they were almost five gallon size. We felt we would
end up killing off too much root system when the roots
were their most vulnerable if we gave them any Nitrogen
for the first three years. Even here I will not give a Maple
any Nitrogen until it is no less than three years old. A
lot of plants have been lost because we felt we had to
fertilize them with Nitrogen when they were way too
young.

I agree that Peat Moss should be used sparingly in soil
mixes for Maples. For us here we want our soil mixes
to retain water but we also want air movement. Peat
Moss is probably better used as a soil amendment in a
warm climate rather than a cool one though. Even
straight already mixed commercial grade potting soils
will work well for us with young plants here. For plants
that have rather sensitive root systems like Azaleas and
Camellias a nursery grade potting soil is probably better
than adding in actual soil to the soil mix. Where we fail
with Azaleas and Camellias is when the soil mixes can
compact by virtue of the mixes becoming too wet and
Peat Moss will only aid in the mixes coalescing and not
allowing air movement once saturated. The quickest
way to kill off an Azalea and Camellias is to not have
air movement either planted in the ground or grown in
a container. People do not realize that we can also have
what is known as a wet compaction and with too much
Peat Moss in the soil mix combined with lots of water
we are looking at creating a wet compaction all on our
own. I'll deal with a clay pan layer any day than deal
with a water compaction problem.

For seedlings we want the roots to grow unimpeded
even if the top growth is sparse. I agree that it will be
the roots that will determine when these seedlings need
to be bumped up into a larger can but most people look
at the amount of top growth they get and then move the
plants into a larger container. If you get good enough
root growth the plants should go from ones into fives,
not into twos.

Another thing to consider is that with too much applied
Nitrogen especially with Maples you can expect to see
more evidence of powdery mildew in the Spring and early
Summer, in a cooler climate more so than a warm one,
more often than you will without the applied Nitrogen.
Less likely with the seedlings grown in full sun but
symptoms will show up more readily grown in filtered,
dappled or high shade.

Jim

 

Well, thank you for the info. I think, since I have 30+ seedlings I will experiment tonight with 10 and re-pot them now in the same size (1gal) but in a better draining mixture with hopes of countering the ill effects of any peat still attached to the root ball.

Any suggestions for a low (or zero) Nitrogen fertilizer? Should I be looking for something with zero Nitrogen or ...should I focus on a formula that has a high Phosphorus ???

Thanks,
Mike

 

With a time release fertilizer already in the soil
mix I would not add in any additional Nitrogen.
A 0-10-10 granulated fertilizer with between
6-10% Calcium in the formulation is all I would
use for seedlings and very young Maples. Had
you not used the fertilizer in the mix then I can
recommend using a 6-12-6 also with about 6%
Calcium as a standard granular fertilizer used in
the Spring only (for young seedlings, not yet
adapted to a one gallon I would not use it). That
is what I use here with only one application made
just as the leaf buds are swelling and watered in
well. I'll come back in the Fall with a 0-10-10
for all of my Maples here.

I would think growing seedlings to keep for use
in landscape plantings that you would be better
off not to use lots of Nitrogen when these plants
are young. What you want is root growth, not so
much top growth on these plants as they develop.
The more root development you get the less likely
you will have problems with these plants later as
they get older and once they are planted in the
ground.

When you pull the plants from one gallons to change
the soil medium check and see what kind of root
development you are getting. If you feel you have
good root growth you can put these plants in a two
gallon if you want to. I had some 4" potted Maples
come in late last year and this year. When I potted
them up I put them in two gallon containers and will
hold them there until I can tell by their roots they are
ready to go into fives.

You can leave your soil mix as is if you are happy
with it but I'd add in some ground fir bark and some
perlite to your current mix. I've used Peat Moss in
the past in some of my soil mixes but the Peat Moss
was in the potting soil I used as my soil mix base.
To counter the Peat Moss I will add in lots of ground
fir bark and some perlite to get better drainage. I can
deal with slow drainage better than you can as with
our heat the cans will dry out much faster that yours
will. What you have to be most concerned with is any
water mold form of phytophthora so for you fast
drainage is almost essential. You can't risk giving the
pathogen a medium to survive in. Pacific Northwest
soils and with your climate using any native soil in
your potting mixes combined with the soil mixes
not allowed to dry out between waterings is real
risky business. The container growers in Oregon
that have had the least amount of problems with
their plants use no soil whatsoever until the plants
are about 5-7 years old. Ground fir and pine bark
if need be in varying sizes of grind and perlite is all
some of the people I know use until their Maples
are five gallon size. We've had much better luck
here with the Oregon container plants that did not
have native soil in their soil mixes.

Jim

 

Thank you very much Jim and all the others - your advice will not be lost on me. I appreciate the time you all took to respond. This has been a great learning experience for me!

Cheers,
Mike
Victoria, BC

 

Talk to some native plants growers, maybe somebody at N.A.T.S. for instance, and seif they will share some of their methods for producing vine maple.

 

Well, I have repotted about half of the seedlings into a mixture of fir bark and vermiculite (I couldn't find perlite in large qty at a good enough price). I noticed most plants that were under 6" tall had compact root balls roughly same size as tennis ball. Thos that were taller had root balls that were about 6" long and 1-2" wide. I will also add diluted 0-10-10 to the water when I irrigate the seedlings.

I will also contact someone local for tips. Anxious to see how the plants will fare!

Thanks all.

Mike

 

Hi Mike,

Good plan as I am at the same point you are, having to repot many plants that are probably suffering from a bagged mix far to heavy in peat.

You mention of liquid 0-10-10 caught my eye as I would encourage you to use a very dilute solution as summer approaches and not very frequently, maybe once every 4-6 weeks. Follow up with a little granular 0-10-10 in the fall about 6 weeks before the first frost for the potted pants. DILUTE.......

I suspect you could be a litte more zealous with the liquid 0-10-10 next year as you develop heathier root systems on the plants. For the stressed roots you have now, go easy.

Good Luck and let us know how you fare.

Michael