Avocado root rot

Jon starts with ...
I've just got two avocado trees and I'm a bit concerned about the Sharwil. The leaves seem to be droopy and a bit curled with a few brown patches, probably just from the sun.

I may just be picking at things but I just want to be really sure. When compared to my Gwen, the leaves are a lot more droopy and softer. Anyone know if it's the problem?

Jon

Jon says...
I give them a water about once every two days, maybe more.

Jon says...
They're in the ground, and the soil is well drained and a bit sandy.

Jantina says...
I can see a bit of what looks like sun damage but other than that they look alright to me Jon. It doesn't look like you have mulched them , and they really benefit from that particularly in the heat. Some old hay, shredded bark (preferably not fresh pine)compost, any good mulch. Give them a good drink and pop the mulch on about 4 in. thick (keep away from the stem though) and it will make life much easier for your avocadoes. We garden on well drained sandy soil and mulching makes a huge difference and slowly breaks down and improves the soil.

Brendan says...
Hello Jon, I can see a bit of 'leaf-tip-burn' on some leaves. Add a fair bit of Gypsum to the soil under the mulch. You could spray the trees with 'Yates Anti Rot' as well. Follow the instructions on back of bottle. That should help.

Jon says...
Here are the photos. The Sharwill is looking much better though now. I gave them both a good water but I'm puzzled as it hasn't been too hot lately. Also, I've noticed all these tiny white moth-like things are always all over the plant, along with my cucumbers and pumpkins. May they have something to do with it?

Jon

Pictures - Click to enlarge
Picture: 1	Picture: 2	Picture: 3

Jon says...
Okay, thanks, that's exactly what they do and there are millions of them. I do have some white oil. Do you know what could be causing the problems with the leaves?

Jon

Brendan says...
Jon, Did you give the tree a good dressing of Gypsum? You could give it a bit more, that should fix the 'burnt leaves'. I see the mulch is too close to the stem of the tree also, I'd move it away, 150 to 200mm. I use plastic rings from Bunnings (~$10), check 'em out. It could do with more mulch too. Gypsum & mulch is the natural enemy of root-rot :-) The new leaves are looking ok, that's a good sign.

Jon says...
Also, I've been using a clay breaker soil treatment mixed in with water. Would that do a similar thing to gypsum or is gypsum more effective?

Jon

JeffW_carina says...
Hi Guys. Just wanted to send through some info on a tree recovering from root rot.

I have a 20 year old Wurtz planted in the ground in a raised bed. Has been giving between 150 - 200 avos a year for 10 years. The tree started 2020 as the healthiest the tree had ever looked. This year with 150+ fruit we have 450mms of rain in 1 week Jan-Feb. The leaves started to brown and then fall within 2 weeks of the rain - the fruit also all dropped. (Sorry I didnt take a photo - but the tree was bare except for about 10 leaves and a few greenish shoots of new growth.

After investigation and some nice posts on this forum it was definitely root rot. After many hours reading info from all around the world, it became clear that root rot is a symptom of Phosphoric Acid deficiency.

The Yates Anti Rot should be seen by all Avo growers as a preventative measure - so aim to do a foliar spray 3-4 times a year - also on Citrus.

Back to my situation. Given my tree had almost no leaves, it was after more investigation that I took to doing 2 things.

I applied the Phospooric Acid as a soil drench - 10 litre per tree as per the directions. I also went an bout some Chemjet trunk injectors http://www.chemjet.com.au/)- I was very lucky to have the company based here in Brisbane. I highly recommend them. Injecting at the same rate as per the instructions - and also mixing on a double strength Seaweed solution.

My tree is coming back to life this spring - early days and I dont expect miracles in the first year, but the shoots popping out everywhere.

So, I would highly recommend every home avocado grower to do preventative sprays of phosphoric acid. There are studies showing you can get better fruit set as well - it is considered a fertilizer in the USA.

Thanks! Jeff - Brisbane

Pictures - Click to enlarge
Picture: 1