Acacia obtusifolia problem

[Pisgah]

Hey there,

So I've been growing obtusifolia from seed in a humid environment in the SE USA (thanks to my friends in Oz), and I am noticing some issues with what appears to be fungal attack of some sort. What do you all think? Should I treat it with Sulphur based antifungals, or is this a nutrient/medium issue? The soil is pretty free draining...

Not all are doing poorly, BTW. These are the exception...

Edited August 27, 2006 by Pisgah

[planthelper]

i had the same thing happening...

i think those accacias are pottasium (i'm not 100% sure) intolarant, darklight and tort would know for sure.

never use fertilizers on them.

aswell keep them drier at times.

aswell they have a symbiosis with some fungi or so going which lives at it's roots and provides the plant with nutes.

maybe try to search darklights posts about phlebophylla and other post as this has been discussed.

[Alice]

acacias are phosphorus intollerant, as are most aust natives.

i had a similar thing with some of mine. i put them in the ground and it went away by itself, plus they grow sooooo much fast in the ground. so if you can, plant them out. otherwise go find some wild wattles, did up some soil from the base and mix it into your pots. hopefully some fungi decides to collonise your roots. = much faster growth.

fertiliser is good, just be sure to get one specifically for australian natives, ie low P.

EDIT: oops sorry, i just noticed that you are in USA, so finding a sample of australian soil/fungi might be a little trickier for you...

about fertilisers, i think the one i use has something like 13N:1P:12K, so maybe just try and find something along those lines, if possible.

also, is the humid environment you describe is natural in your area, or you have created the humidity artificially? australia is a relatively dry country, so maybe they dont like the humidity.

good luck and keep us posted of the result

Edited August 29, 2006 by Alice

[MarsOfOld]

Two of the three of mine are also doing similarly after being fertilized with a dilute solution of Miracle-Grow. I am going to try to start using a dilute solution of Potassium Nitrate (saltpeter). No phosphorus, yet plenty of potassium and nitrogen...

[sobriquet]

Plathelper and Alice have the right idea. Most Australian natives are Phosphorus intolerant.

I'd basically try to use only sulphate of Potash for K, and Urea for N; with extremely weak general fertiliser for the minimal P it needs.

Some specialised nurseries around your parts might even have low-P granular type fertilisers. It's plentiful here so maybe someone can send you a small bucket of it (Osmocote Native), and it should last you a long while.

Edited August 29, 2006 by eNo

[indigo264nm]

I had that EXACT same problem and posted some pics a while back (maybe on EBA) with some thinking that it wasn't a nutrient toxicity but a more pathogenic problem.

The situation was remedied by putting it into the ground, and mulching\mixing in leaf litter and soil collected from under some A. longifolias. The leaf litter was kept moist in a container after some native native mix in order to try and increase volume of soil with symbiotic fungi. It was planted next to an established A. maidenii

For the next lot of A. obtusifolia I propagated the mixture that had been kept moist and covered was mixed in with aus native potting mix (with prop sand and perlite) and put in tubes after pricking out. This seemed to have a quicker impact on the growth of these seedlings and they were much healthier.

I will say however that I am 100% certain that the problem with my first obtus seedlings was not pathogenic but infact P toxicity as I have seen the same effect on a picture of a young Banksia suffering from the same deficiancy. Putting it into the ground seemed to remedy (after a couple of months) the one plant which was not so badly affected (whereas my other two died after transplanting), and I believe that introducing symbiotic fungi into the soil around the plant contributed to it's recovery.

Since you're in the states you will have to look into buying the fungi to innoculate (if you can be bothered) as obtaining leaf litter will be difficult. Planting in the ground may not be so wise either because the P concentration would be higher in your soil.

Good luck...

[Pisgah]

Humidity here is naturally high. That could be a factor.

I may have hit these with Indonesian bat guano (High Phosphorus) which would be a bad thing.

I don't have any local acacia here, but I wonder if Albizzia, Desmanthus, or Mimosa would have similar helpful micro-flora?

An interesting side-note. I have been spraying these Acacia with harpin protein, and it seems to be helping to stop the progression of phyllode necrosis.

Thanks for all the help!

[indigo264nm]

Humidity here is naturally high. That could be a factor.

I may have hit these with Indonesian bat guano (High Phosphorus) which would be a bad thing.

I don't have any local acacia here, but I wonder if Albizzia, Desmanthus, or Mimosa would have similar helpful micro-flora?

An interesting side-note. I have been spraying these Acacia with harpin protein, and it seems to be helping to stop the progression of phyllode necrosis.

Thanks for all the help!

I have my doubts as to whether Albizzia, Desmanthus, or Mimosa would have the same microflora as from my understanding in this situation the symbiotic fungi is more of an evolution to cope with poor soil conditions in Australia with naturally low Phosphorus levels. The commercial innoculation of such fungi in growing medium seems to mainly be applied in the field of Australian native plant propagation, however I am aware there have been proven results with virtually all plants - regardless of whether it is economically worthwhile in the long run.

[Pisgah]

Are these Australian native mycorrhizzial innoculants available commercially?

[indigo264nm]

I have been led to believe so... I will have a look through last semesters hort notes and see if I can find any mention of a place to order from.

[MORG]

Since you're in the states you will have to look into buying the fungi to innoculate (if you can be bothered) as obtaining leaf litter will be difficult. Planting in the ground may not be so wise either because the P concentration would be higher in your soil.

I have a vague recollection of reading somewhere (Erowid?) that Acacia maidenii is established in some places on the west coast of the US.

Anyone know anything a bit more concrete?

Maybe you could find some planty people to send to some soil from these pops if they do indeed exist.

[Alice]

The commercial innoculation of such fungi in growing medium seems to mainly be applied in the field of Australian native plant propagation, however I am aware there have been proven results with virtually all plants

apparently something like 90%+ of the worlds (known) plants form mychorrizal relationships. It is strange that the main model organism in plant biology is Arabidopsis, which is one of the few plants that do not form these relationships.

[DocAzz]

as a sort of related question... Does anyone have any, or know of any websites that contain, detailed pictures of the a.obtusifolia? I want some to imprint them in my mind for when I go for a hike soon.

Ta