How often have you been watering? Our sand just loves to wick the moisture away from the potting soil surrounding the trees roots. It is why I always try to bareroot the trees I plant.

Hi Corrine

I don't know what happened to your avocado because it could be a lot of reasons. You said that the soil was bad, did you amend when planting? a common problem for avocado decline is root rot, that is the reason that I planted my two avocados in a mound. For me, they are care free, I have never spray anything on them and every year they have an abundant crop, this year it is not different.

My young avocado

And my older one, loaded with fruit like every year

Silvia

It appears you may have 'burned' the leaves with the excessive application of the soapy/neem oil spray. If the tree is healthy it should come out with a flush of new leaves.
Sooty mold can be washed off the leaves with running hose water and a soft cloth (an old clean face cloth). The only way sooty mold hurts a plant is by blocking the sunlight to the leaf.

Lou

You're likely killing it with kindness. You have to be very careful with neem oil. In hot weather it will burn your trees, and some species just cant handle it at all. Just remember a simple rule: if it's hot and sunny, DO NOT SPRAY. Wait until late afternoon at least.

Sooty mold is not the root of a problem, it is a symptom. Aphids, whiteflies, and other sapsuckers drink the plant juices and then poop out a sugary substance called honeydew. This drips onto nearby leaves and the sooty mold is growing on the honeydew. It's actually very helpful because its a giveaway that something is sucking your plant dry. Then, and only then, should you go about treating for the aphids. I would not preemptively spray for aphids, myself.

I think the best thing you can do is leave your tree alone for now. Just ensure that it's getting enoug water. (But don't go crazy either, too much water is also very bad.)

Thank you everyone for your thoughtful replies. I kept reading whatever I could find and also wrote to the gentleman who sold me the tree. It seems the neem oil is most likely the culprit. I burned the leaves with too much attention. I've thought it would be harmless to use the little bit of oil/soap I had left in the sprayer on the tree. I mix it up to battle whatever it is that is eating my lettuces. From now on I'll mix less or dump the leftover.

We have an irrigation system that goes off 2x week and I normally get out and hose water many of the plants and shrubs another two or three times a week. Everything is so new.Five months ago the yard was only grass. We put in a paver patio and the lawn guy had some trouble riding his mower between the back side of the patio and the new cyclone fence we had installed in Dec.. I turned it into a rock garden with a solar fountain, firecracker plants, a bit of ginger, snow on the mountain and some MandeVino. and passion fruit vines. On either side of the patio I planted several serissa and Mexican Heather shrubs plus a Jatropha on each side. I saved a space on each back corner to plant a palm tree but haven't decided what type I want yet. We built two 10'x4' raised beds for our veggie gardens. I made one corner of the yard a large patch for corn and watermelon.I have a small fence around the perimeter to keep the dogs out. We also put in a lychee tree, mango, black mission fig,and a meyer lemon/key lime cocktail tree, in addition to the avocado. I also planted a bottle brush but it appears to be dead.

The soil is actually quite good here at the new house. This whole area is sand and it looks like they've laid several layers of topsoil and sod, so the top 12' is dark and rich. When I plant, I dig huge holes and mix in some black kow compost and potting soil. The raised beds were filled with peat moss, vermiculite, topsoil, and composted manures.

My next mission is to dig a 25' bed about two feet wide along the back of the house which is currently bare. I can see where the lawn man beats the stucco to death with the weed whacker, so I've decided to make it into another bed. I'm going to plant things that grow tall in there like okra, icicle radishes and sunflowers - found some sweet potatoes that I'm going to toss in there as well.

All of this has been done since January. I'm currently trying to teach myself planting times and how to keep the soil rich and fertile while eliminating pests as naturally as possible.

I write mini novels so thanks for hanging in here. Maybe soon I will post some before and after pics of the work we've done on the yard thus far. Like I mentioned, I'm brand new to gardening. I wanted to do this at our old house but a mile from the ocean made for very salty air and like I said, they filled in the yard with crushed cement. It was nearly impossible to dig through it and the few things that I tried to plant died immediately. I just didn't have the time, energy or money to tear it all out and start with new soil and salt resistant plants,

Anyway, thanks again. I will leave the avocado tree alone and hope that it develops new growth. I'm sure I'll be around asking lots of questions. I like to learn from people who enjoy the same interests, especially when they share stories of both their failures and successes. I learn from other people's mistakes as well as my own and enjoy celebrating the success of others,.

Ciao for now!

Just FYI if you plan to plant any more citrus trees. black Cow can actually be harmful for citrus loving plants. It can raise the pH of your soil. I would recommend you try peat moss for any acid loving plants such as citrus, kiwi, muscadine, or blueberries.