10 replies to this topic

[subaer]

I have a 70cm acacia acuminata growing in a smallish pot. Some of the phyllodes are starting to turn yellow at the tips. I've had a similar plant already turn yellow. What could cause this? What can I do to remedy this?

[cacti jihadist]

photos would help, my guess is nitrogen deficiency. ( only a guess though )

(or perhaps if it is the tips of the leaves burning, perhaps over fert ? )

Edited by tipz, 05 March 2012 - 09:01 PM.

[jwerta]

tipz is probably right but ill add this anyway... acacias hate being in pots they love to be able to spread there roots far and wide I doubt that's why the leaves are going yellow but im sure putting them in the ground would help out allot

[phyllode]

Probably Nitrogen deficiency. Yellow spotting, rather than tip colour change, would suggest possible root pathogen. Potassium also helps.

[satyr]

Not having a diagnosis for the yellowing ...
but I was under the impression that acacias are especially addapted for soils low in Nitrogen due to the symbiosis with Rhizobium nodules associated with their roots which fix atmospheric nitrogen, and hence fertilizing can easily have negative effects.

[poisonshroom]

Thats true, but in pots they may not develop the nodules properly because the bacteria that form them often isnt present in the soil or on the seeds.

[planthelper]

they can get yellow phyllodes aswell from some causes unknown to me, i'm with satyr.

if the tips get yellow for example, it's unlikely to be a N problem, because N deficancy starts with the older phyllodes!!!!
i have seen this aswell, even with plants planted out.

repot or plant out.

[SallyD]

Are there any signs that the plant is rootbound ?
When they get rootbound the new growth slows and gets more compact and the tree can't take up nutrients or water properly.

edit: I've seen ants move into a pot, making the soil repellent and causing similar problems with Acacias.

Edited by SallyD, 06 March 2012 - 10:45 AM.

[Marcel]

I used to severely underwater my baby Acacias (obtusi as well as acuminata) and then be surprised that they got yellow and crunchy phyllode tips. I figured that they are natives and hence don't need as much watering. I was wrong, I guess. Maybe up the water for a while to see if that makes a difference. Once they're bigger, they don't need much water.

[LokStok]

Thats true, but in pots they may not develop the nodules properly because the bacteria that form them often isnt present in the soil or on the seeds.

Yep, i agree. I think the go is to carefully remove a small amount of soil from around the root system of an established acacia (any, I used a big old A. iteaphylla), and add that to
your potting mix.

[phyllode]

The rhyzobium make the nitrogen freely available to the plant. Obtusifolia in particular responds very well to high nitrogen/low phosphorus slow release fertilizer. This has usually remedied yellowing of phyllodes, particularly when whole phyllodes become paler.