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space cadet swami

A. obtusifolia seedlings not to good?

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Was hoping somebody could help me with a small dilemma.

About 6-8 wks ago I got about a 60% germination rate with 20 obtusifolia seeds. So 12 seedlings where cruising along (very slowly) when I decided to transplant up about 2 wks ago, into bags. All of my A. maidenii (12 of, @ 80% germination) transplanted up fine & are powering along twice as fast as the obtusifolia's.

Anyway about half of the obtusifolia's (6) have leaves browning & falling off. Most of these do have new growth coming on. They are well shaded, but did get a lil bit of afternoon sun about a week ago. Could this be the cause & if it is, should they recover or will they more than likely die? From what I've read the obtusifolia's seem to be quite sensitive. A couple of these seedlings are looking quite bare, with no signs of new leaf development. :(

Any help would be appreciated.

Thanks "space duck"

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i've had similar with maidenii, i think could be to do with nitrogen levels, i've been tempted to find a big melanoxylon, which are everywhere where i am, and see if i can scrape some nitrogen fixing bacteria from around its outer roots, as an experiment just enough to see if it might help to replace those that might be lost in the transplanting

it might also be that you just have to treat em tough, it can be worse to nurse bad genetics in unsuited conditions, as long as you've got a few strong plants you can always grow more :wink:

Edited by bulls on parade
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Good idea bulls on parade. The thing to keep in mind with nitrogen fixing bacteria is that there still needs to be some nitrogen available for them to 'fix'.

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I was under the impression that nitrogen fixing bacteria is that they "fix" the nitrogen that is in the earth's atmosphere (some 80% of all atmospheric gases), not that which is already available in the soil.

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I've treated mine pretty tough, once it had about 3 true leaves I moved it outside, during a 30+ degree week, copped a little burn but smashed through it and is still throwing out new growth :)

Got any pics of em mate?

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I was under the impression that nitrogen fixing bacteria is that they "fix" the nitrogen that is in the earth's atmosphere (some 80% of all atmospheric gases), not that which is already available in the soil.

 

just reading up on it man i think you're right, Rhizobia and Frankia, metabolize something from fallen vegetation as it decays which isn't totally available to the trees, so they just grab and circulate extra nitrogen molecules about, so it sounds like it would take a while to become established before it'd be a benefit for other plants.

They're are beautiful trees.. we had lightning strikes here through the summer and first regrowth after fire damage is Acacias Everywhere, little parent plants that in even 1 year will be bushy floribundas giving shade to the grasses and Eucalyptus and everything else

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Good on you guys. You're right. I just find that adding nitrogen boosts both plant and node growth, especially in obtusifolia.

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I'll see if I can get some pics up tomorrow...I had bad light the other day, so I thought I'd just fish for some answers. I'm still a bit confused as to why the maidenii's are doing fine in comparison.

Appreciate the feedback guys...pics coming soon.

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post-11175-0-80093600-1332369952_thumb.j

A. obtusifolia's

post-11175-0-26069300-1332369911_thumb.j

A.maidenii's

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One of the not so good obtusifolia's...you can see the 2 in the background are doing a lot better.

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One of the better obtusifolia's

post-11175-0-99332800-1332370078_thumb.j

Nice healthy maidenii

post-11175-0-39877100-1332370111_thumb.j

Obtusifolia with a bit of hard work ahead of her

post-11175-0-22270800-1332370150_thumb.j

Psychotria viridis for good company...you can see the 12 on the left are the obtusifolia's....

Like I said earlier, they were all transplanted at the same time from seedling tubes, into the same mix (osmocote native).

Yet the obtusifolia's look like they're doing it hard, compared to the maidenii's.

If the nitrogen fixing is the issue, then shouldn't they all be struggling?

I don't know...I've never grown acacia's before. So these issues are all very new to me.

All the help is appreciated...thank you guys.

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post-11175-0-04419200-1332370019_thumb.jpg

post-11175-0-99332800-1332370078_thumb.jpg

post-11175-0-39877100-1332370111_thumb.jpg

post-11175-0-22270800-1332370150_thumb.jpg

post-11175-0-26069300-1332369911_thumb.jpg

post-11175-0-80093600-1332369952_thumb.jpg

post-11175-0-17732500-1332369989_thumb.jpg

post-11175-0-04419200-1332370019_thumb.jpg

post-11175-0-99332800-1332370078_thumb.jpg

post-11175-0-39877100-1332370111_thumb.jpg

post-11175-0-22270800-1332370150_thumb.jpg

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I never used nitrogen fixing bacteria on my obtusi's, a few of mine started doing what yours are, moved it back into my seedling box under lights for a week or two and it picked back up, few of them died but I think it's just a case of bad seed

Here's where mine are at, started with 8 got 3 left, all sowed at the same time, the bigger of the 3 didn't sprout until a week and a half after the other 7 shot up.

The two smaller ones did what yours are doing, they managed to tough it out though:

ca4d7a4e.jpg

96abf8f1.jpg

My plan is to let the strong one grow, then when he's at a decent size I'm gonna start trying some air layering to clone it :) if the weaker ones don't die then that's just a bonus for me haha

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i reckon they'll be ok. Probably was that afternoon sun hit which shocked them a bit. Dont over

water to compensate. A weak solution of Seasol will help.

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I'm starting to think it was the arvo sun. I think the maidenii's are faster growing & I may have jumped the gun when I transplanted them all at the same time...maybe I should have waited a couple more weeks for the obtusifolia's...so they were a little more established.

Thanks again for the input guys

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they hate the tropics, unfortunately.

most obtusi die, in the north.

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They <obtusifolia> in my experience seem fussy about soil mix. They like sandier mixes, and hate moist rainforest soil. When I've used purchased potting mix made of mainly wood chip they have often gotten the leaf browning or done poorly. Osmocote for natives works well for my trees, but no it isn't organic.

Edited by phyllode

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The true leaves on the seedlings appear to going red yeah???

Phosphorous toxicity. Commercial native mixes can sometimes be too high in nutrient content for youngns, particularly phosphorous. For the first stages of seedling growth require no fert at all, and for particularly hardy Acacia's require little fert to grow in general. Burnt tips on mature phyllodes is a symptom.

Try maybe a cheaper brand of native potting mix than osmocote or thrive... the cheaper ones are generally pretty nutrient low and don't contain as many additives like ferts and moisture retaining chemicals - this is actually a good thing for these seedlings.

Maybe add some coarse sand to a 1:4 sand:mix ratio as well whilst they're that young.

Edit: I just want to clarify that I know mild red colouration is common on obtusifolia, but my seedlings never showed it and also it's visible on some of your maidenii.

Edited by -=IndigoSunrise=-

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Looks like about half of them are gone.. :(.. I'd say I'll definitely get to keep 4, maybe more if I'm lucky.

Maidenii's are powering like there's no tomorrow, I expect it won't be long before I see some mature phylodes.

I've put in another 6 obtusifolia seeds, I'll get it right eventually.

they hate the tropics, unfortunately.

most obtusi die, in the north.

 

I'm at 1000mtrs & inland, with hardly nowhere near the same humidity as on the coast...so...hopefully...eventually...maybe.

10:30pm - 24deg - 79percent humidity.

I'm crossing my fingers...

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They <obtusifolia> in my experience seem fussy about soil mix. They like sandier mixes, and hate moist rainforest soil. When I've used purchased potting mix made of mainly wood chip they have often gotten the leaf browning or done poorly.

 

For the first stages of seedling growth require no fert at all, and for particularly hardy Acacia's require little fert to grow in general. Burnt tips on mature phyllodes is a symptom.

Try maybe a cheaper brand of native potting mix than osmocote or thrive... the cheaper ones are generally pretty nutrient low and don't contain as many additives like ferts and moisture retaining chemicals - this is actually a good thing for these seedlings.

Maybe add some coarse sand to a 1:4 sand:mix ratio as well whilst they're that young.

 

So upon waking up & checking on the state of my girls... :(...things are slowly but surely going downhill for the obtusifolia's.

So, I bit the bullet & re-bagged all the obs. into a coarse sandy mix. The native mix looked too heavy & wet when I got it out of the bags...mind you the maidenii's seem to love it. The roots are looking healthy as...but they hadn't moved out of the original mix they where sprouted in, so hopefully in the sandier mix they might come back to me (don't go into the light.. :innocent_n: )

Thanks for the advice guys, hopefully I got to them in time.

Will keep you all posted.

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What I generally do is germinate Acacia seeds directly into 2 inch tubes. I make a mix of 5:4:1 peat\sand\perlite and put a ~3mm layer of vermiculite on top to keep moisture in with a little layer of perlite at the bottom of the tube for drainage.

By the time it's necessary to move into bigger tubes the seedlings are generally ready to handle native potting mix with a bit of perlite or coarse sand mixed through.

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eyy i know its a bit off topic from obtus but my acuminata are about 3 weeks old and 2 inches high is that a normalish growth rate?

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hey space cadet, i think overall your method was wrong but it is a good learning experience. acacias are best germinated in late november or early december and kept moist but not soaked over summer while they grow, first under shade cloth or in dappled shade or morning sun and then moved into full sun a few months in to prepare them for planting out. using the standard tubestock pots that you would see in a native plant nursery is enough to get a 12 inch plant (or more) by march/april ready to go into the ground mid-autumn or early to mid winter without the need to transplant at any time, or if you chose to move them to a bigger pot you could do that also at that time. that is pretty standard for all acacia species and pretty much any potting soil that isn't too rich will do if the timing is right. they don't like being transplanted so soon after germination because root development is poor and especially not when the weather is cooling off. nevertheless many may survive but nov-april is the time to grow acacia tubestock so i think you started a bit late. rhizobium should form in the pots without the addition of soil from under an acacia don't ask me how though but i love the smell of an acacia when it comes out of the tube for the first time. i'd stop meddling with the ones you have and just cross your fingers and go crazy this november sowing more. maidenii would seem to me more resilient to the effect of late germination but again it's just a hunch.

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