What is eating my avocado trees?

[Malia]

Experienced avocado growers, please help.
The pictures below are of brogdon ( darker green) and super hass . Brogdon was planted 1 year ago, super hass 2 years ago. I think both from 3gal containers.They have not grown ever since. The branches look weird, with some black coating. Also a little grey/white coating. Brogdon started sprouting branches in the lower part, but I am pretty sure above the graft line. The trees sprout a lot of buds, as you see in the pictures, but not much results from it. Should I spray sth?
[zurl=https://postimg.cc/8snDympP][/url]

[Malia]

Pictures of entire plants

[kingoceanos]

I'm no expert but it looks like to much sun and they need to be up on a mound ( wet feet) are not good for avocados. You could paint the trunk and branches with a 50 percent white latex paint and fifty percent water solution. Don't forget to feed them also. If you don't want to paint then a shade cloth on a frame will help. Some of the more experienced growers might add their advice.

[Malia]

Kingoceanos, thanks! What you are writing makes perfect sense in the case of Brogdon. It is sitting in full sun. I will put it under shade, following your advice. Super hass is in half shade though.
With the recent drought and sandy soils of Palm Beach County wet feet probably are not the issue. I will add fertilizer.
BTW, did any of you encountered that black covering on your avocado trees? It covers almost all the branches. In some spots (upper part of the twigs), on the other hand, it looks like white flour. At first, I thought the plant got dirty from the soil, but now I do not think so anymore.

Another question: Nematodes. Did any of you have problems with them and avocados? They ate my kilo guava and cucumbers. Internet says avocados are prone to nematodes, but does the damage on pictures look like nematode damage?

A lot of questions, but I am really an inexperienced gardener.
Thanks!

[swincher]

In some spots (upper part of the twigs), on the other hand, it looks like white flour.

The white powdery residue that sometimes forms on avocado stems is from evaporated sap. Look for signs of insect/beetle damage, but also could just be from wind, pruning, or maybe the talons or claws of a small animal climbing or perching on it. The green "skin" on recent avocado growth gets scratched pretty easily.

[Malia]

Thank you all for the replies.
I showed the pictures yesterday at Excalibur and an employee there told me it looks like fungus and recommended Copper Fungicide.
I sprayed today and will report success/failure later.

[850FL]

Avocados can be difficult to establish in Fl.. you have at least a couple different things going on.

The  yellowing branches and the brown spots on the leaves are both sunburn. I’d reccomend to put a shade cloth or doubled up window screens above the saplings. Avocados pretty much like full sun, so your location shouldn’t be a big problem (unless it’s in a low flood prone spot). Saplings just need a couple years of filtered light to establish properly, and they will handle the sun when established. I would only recommend transplant as a last ditch effort!!
Also paint the stems with the right ‘paint’. I have used pulverized zinc oxide powder and calcium carbonate on the stems before to reflect heavy sun.I mix those reflective powders with sulfur to kill and ward off fungus. Try not to get much on the leaves. Some people use actual paint like mentioned.

Problem 2 is that sooty-looking fungus on the branches. Nearly all of my avocados get this. I don’t know exactly how harmful it is, but I have recently been having mid-branch rotting which this fungus might be contributing to (in the picture below) This is why I add sulfur to the avocado ‘sunscreen’. I believe copper is a good one too, among other more synthetic antifungal compounds..

But there are also other fungus to watch out for, like bad root funguses, and other pathogens ( you’re probably right about the nematodes too!).
 Phyto. cinnamoni, verticilium wilt, and the ambrosia boring beetle fungus complex are fungus problems to watch out for in Fl.
and they can really infect your saplings when you go to transplant. I have seen avocados suffer greatly if you damage the roots during transplant and have had quite a few slowly die off after..
Boring beetles and other pests especially sense when an avocado saplings is stressed for whatever reason, and that is often when they come in.

Also you will want to mound compost and mulch around your saplings. It will help a lot. Add some gypsum and pulverized limestone in the mulch as well, it may help with the root fungus.
 and make sure they don’t get root rot from flooding.

[Malia]

850FL, thank you for such a comprehensive answer.
Where do you buy zinc oxide powder and calcium carbonate and sulfur? What proportions do you mix for your paint? ? Lime and gypsum, I checked they have them at home depot. Any special proportions for these?
The instructions on copper fungicide tell to spray once a month. How often do you paint?

I can see the trees are truly distressed because they really want to sprout the twigs. They have plenty of twig buds. And these branches sprouted from the ground in Brogdon...
I bought mulch today. Will need to make another trip to buy the minerals you are recommending.
I have not yet seen any of the pests you are writing about. But definitely, I need to take precautionary measures.
Compost: I used to make compost in a composter but unfortunately I got a lot of palmetto bugs and larvae in it, so I now just empty my kitchen waste under my backyard trees. A gallon every day. I suppose these avocado saplings get such food once every two weeks. This is a backyard so nobody can see piles of apple and orange peels under my trees. The trees seem to like it. Do you think it is equivalent to store-bought compost? Would you advise against such unprofessional practice?

I saw the damage in your picture. May I ask are you Gulf or ocean coast? how far are you from the water? I am within walking distance to the ocean and I thought this contributed to the fact that before this avocado thing I have not had any fungus... Maybe more humidity contributed to this mid-brach rot. Just wondering...
Thanks again!

[850FL]

850FL, thank you for such a comprehensive answer.
Where do you buy zinc oxide powder and calcium carbonate and sulfur? What proportions do you mix for your paint? ? Lime and gypsum, I checked they have them at home depot. Any special proportions for these?
The instructions on copper fungicide tell to spray once a month. How often do you paint?

I can see the trees are truly distressed because they really want to sprout the twigs. They have plenty of twig buds. And these branches sprouted from the ground in Brogdon...
I bought mulch today. Will need to make another trip to buy the minerals you are recommending.
I have not yet seen any of the pests you are writing about. But definitely, I need to take precautionary measures.
Compost: I used to make compost in a composter but unfortunately I got a lot of palmetto bugs and larvae in it, so I now just empty my kitchen waste under my backyard trees. A gallon every day. I suppose these avocado saplings get such food once every two weeks. This is a backyard so nobody can see piles of apple and orange peels under my trees. The trees seem to like it. Do you think it is equivalent to store-bought compost? Would you advise against such unprofessional practice?

I saw the damage in your picture. May I ask are you Gulf or ocean coast? how far are you from the water? I am within walking distance to the ocean and I thought this contributed to the fact that before this avocado thing I have not had any fungus... Maybe more humidity contributed to this mid-brach rot. Just wondering...
Thanks again!

Well you’d have to research proper proportions I suppose.
I use the Bonide pyrethrins & sulfur ‘fruit tree’ concentrated product (I don’t even know if they sell it anymore, just make sure whatever product you use has sulfur, copper, or another antifungal. The pyrethrins are a plus for insects. You could mix in a different insecticide if you wanted. But if you do, beware of neem oil because it can cause sunburn in full sun- not saying it’s not effective against insects though). then I dilute that concentrate a little bit, and then mix in an adequate amount of pulverized zinc oxide or calcium carbonate (chalk), which you can find cheaply online, and then paint this mixture onto the limbs- and only when it’s sunny so it can dry on. I am a bit hesitant to use actual paint although I bet it’s just as or more effective against the sun.
I have also diluted small amounts of this mixture in a few gallons of water and flushed the roots with it to protect against potential fungus and pests in the root zone- especially with root stress and root rot.. I don’t have exact measurements just eyeball it, so maybe somebody else has a more specific protocol.

Gypsum is calcium sulfate. It helps loosen soil which is good for avocados and the sulfur also controls fungus. I couldn’t tell you exactly how much to use.
You live in south Florida so maybe your soil already has enough limestone in it (usually calcium carbonate and magnesium carbonate), but in my area I always add some to beef up the mulch a bit.
And don’t buy the dyed mulch just natural chips.
By compost I basically just meant mulch, leaves, rotting bark, chopped debris, etc that will turn into compost.

As for the avocado in the picture, I am a couple miles from the bay and just a few more from the ocean. The tips and branches almost definitely had some type of fungus, I don’t know exactly what yet but I am researching.

[Malia]

850FL, thanks again. I did use neem oil on my avocados. This might be the cause of sunburn. And yes, it is ineffective. I have an entire zoo in my front and backyard.
I am collecting my ingredients now. I have some time to do this because the forecast shows rain for the next 10 days or so.
I suppose this is your product: https://www.amazon.com/Bonide-218-Concentrate-Citrus-32-Ounces/dp/B00192FZ30/ref=sr_1_1?dchild=1&keywords=Bonide+Citrus%2FFruit+and+Nut+Orchard+Concentrate+Spray+16+Fl+Oz&qid=1622570895&sr=8-1

No copper in this mixture, but I suppose I can mix in my liquid copper fungicide, I should not cause an explosion I assume.
Yes, they say we have alkaline soil with some limestone in it and anytime I dig I can tell it is pretty loose.

So it looks like fungus feels better more inland.               

[Fishinsteeg234]

I would recommend a thick mulch ring around your plants. 3’+ diameter, 4”-6” high, but not touching the trunk. Organic local mulch is best, not the dyed stuff bought in bags. Most tree service companies give mulch away for free. This mulch will hold moisture, hold nutrients and fertilizers, and will slowly break down into back gold for your young trees. Renew this mulch ring when you see it breaking back down to ground level, once or twice a year.

Full sun can be harsh for a small avocados, the mulch will help keep it moist. A light shade cloth or dappled shade for a bigger potted plant might also be beneficial for the first year or so.

The black type sooty mold on the green branches is normal for florida, it will disappear when the bark develops.

Good luck

[Malia]

Fishinsteeg234, thanks a lot for your input. I am doing all the procedures recommended. Reading your post and those of 850FL, I think the main issue might be nematodes. I just need to finally do this and apply beneficial nematodes. Never done this before...

[pineislander]

Watch this video on avocado mulching. Note that they say avocados evolved in rain forest conditions growing in forest systems with plenty of leaf litter. They have fine surface roots to feed but those roots have very few hairs to absorb nutrients. They show the roots. They also show massive amounts of mulch being used on new and established trees, in full sun, with irrigation.
https://www.youtube.com/watch?v=fYYZuNjnvbk


Florida sand is a very different situation compared to where avocado naturally grows. It has few nutrients, dries out quickly, and since you have it planted outside a forest system with no mulch you are getting farther from the conditions it needs.

I imagine the roots of your tree have remained very short and haven't expanded enough to let it grow. You need to change that by giving it conditions the roots will grow into then it will start to expand it's root system.

You could emulate a forest system fairly easily at no cost or labor. When you mulch out at four feet around your tree, plant some pigeon pea seeds in a ring around it. They grow very easily like any bean. They don't need much water but to grow avocado you know you must irrigate them to get anything. When the pigeon peas get up they can be pruned whenever you like to shape them and reduce or expand the amount of light for your avocados. They can grow 6-8 feet or be kept at any height or density you want. Buy a pound of them at most grocery stores under the Goya label in either the bean section or the Hispanic section. Try cooking them like any dry bean. The bonus is that they will make peas for you by Fall and the green ones shelled out are very good.

Property I bought had a row of very poorly growing avocado. They had suffered from no water, mulch or fertility and were almost leafless.
I mulched them heavily using small solid wood logs covered with chipped mulch, installed irrigation and fertilizer. Within a year all the trees came back and have been bearing good ever since. They have created their own forest ecosystem now and I even have coffee, Barbados cherry and other plants thriving underneath them. So, I think avocado really is happy now with that treatment.

This is when I mulched them hard:


This was how they responded:

[Malia]

Pineislander, love, love your advice! And the beautiful story about your avocados. The video is awesome. I will do as you advise. I see you put some tree trunks around your avocado trees. Do you think areca palm trunks will do? Or will they attract pests?

[Malia]

That might be a dumb question, but how do you apply fertilizer? Do you remove the mulch and put the fertilizer under or just put it over the mulch?

[pineislander]

Any palm is good it usually breaks down faster than hardwood or softwood. I put the wood out a ways not especially close to the trees. I usually fertilize before mulching but these trees I haven't fertilized for 2 years they are running on organic matter and whatever it has absorbed. I see a lot of decomposers like millipedes and even some worms under the trees. I even plant the pigeon peas around well established avocado trees, some have other fruits like surinam cherries, Ice Cream Beans, Monstera deliciosa, and Curry leaf trees, some Queen Emma lilies, eddoes
plants, the dominant ground cover under the plot picyired is now Piper sarmentosum, lovely shiny leaves and they are even edible, some of it has a border of lemongrass, some has been colonized by sunshine mimosa and perennial peanut. One section I throw old banana trunks underneath the avocado trees.
Heck, they said these trees evolved within a forest environment so I am literally growing a forest around them with understory plants. One benefit of creating an understory is that when the avocados shed leaves they don't blow away they get trapped within the system. The other plants drop leaves too. I actually haven't added chipper mulch for a couple of years.

[850FL]

Pineislander What types of avocados do you grow? Guatemalan and West Indian? I am most interested in Mexican avocados.. but which are hardier long term in your experience in Fl?

[pineislander]

brogdon, mexicola, nishikawa, golden, choquette, day, marcus pumpkin, russel, simmonds, donnie, maybe some unidentified. Not sure if these are G, WI or M or crosses. They do give me 6 months harvest some years. They were all here when I bought the place. I will be planting a lot more this summer my plan is direct seeding this time and grafting in place next spring.

[850FL]

Mexicola true Mexican. Brogdon and Nishikawa Mexican hybrids. The others WI and G or those hybrids. You should seed from a good rootstock variety. Walden and Lula are traditional for south Florida. I want to try Mexican as rootstocks because of the cold tolerance and some apparently are more phyto resistant. Do your avocados get any types of bad fungus or pests and which ones are most resistant of yours?