Here are some more suggestions for yellowing avocado leaves.
Since avocados are considered a plant that is generally free of diseases, TheGardenLady offers this list of possible problems an avocado tree can have.
Generally avocado trees are tolerant of a lot of water if there is EXCELLENT drainage. Drainage is very important. But if you feel that you have over-watered your plant, it cannot hurt to cut back on the water. Test the soil with your finger before watering again and water only if the top of the soil feels dry. The frequency of irrigation depends on the temperature. In hot, dry weather, the avocado tree may require irrigation every day. As a general rule, a potted plant in a container measuring 6 inches in diameter needs water when the top 2 inches of soil feels dry to the touch. A larger container measuring 8 to 10 inches in diameter is ready for water when the top ½ to 1 inch of soil feels dry. Avocado trees like the soil to drain quickly.
Hopefully, when you transplant the avocado tree, you do it carefully because the trees have weak root systems and sections of the root balls can break off during transplanting. See here.
Avocado trees prefer full sun but need protection from strong sun until they develop a deep root structure and dense foliage to protect the sensitive bark. So young avocado trees have to be slowly introduced to the sun or their leaves can yellow. See here. Even after transplanting them into their final planting site, if they have not become used to the bright sunlight, you might have to give them some shade at first.
To learn how to grow avocados at home or a container, you should watch this:
If you’re interested in why people fail at growing avocados, you should watch this:
If you’re interested in some helpful tips for the backyard grower, read this:
About a month ago I transplanted 2 young avocado trees (bought at the local nursery) into large containers (their spots in the orchard aren’t ready yet). I had watered them 2x/wk week in the beginning and then 1x the following week because the soil was staying wet and I was afraid there wasn’t enough drainage. One of the trees’ leaves started yellowing, even though it gave me flower buds already. So I stopped watering it, afraid that’s why it was yellowing (the other one is fine). It now has all the upper leaves completely yellow and some turning brown and curling. The lowest ones are still green. I’m not sure what to do? Water it or not? The soil still appears moist.
Fungus is the most serious disease of avocado trees, which may be the problem of your avocado tree. As you wrote, you over-watered the plant and also the plant might have had poor drainage in the pot you put it in. You should take your plant to your nearest Agriculture Extension
office for an accurate diagnosis. They can offer you, for a fee, lab tests and soil tests to see if your tree has a fungus. (see here)
It is difficult to diagnose the problem from just a brief paragraph. Here is what UCDavis has to say about avocado diseases.
TheGardenLady received this question from Michael.
I’m not seeing a black monarch. It’s a butterfly with black wings and orange tips. What is it?
We readers of TheGardenLady column also wish you had sent a photo of the butterfly with black wings and orange tips. Or perhaps you could tell us the area of the country where you saw this spectacular butterfly. Both a photo and the location could perhaps help us figure out which butterfly you saw.
Could it have been Siproeta epaphus with the common name of Rusty-tipped Page or Black and Tan butterfly?This butterfly is seen in the southern part of the US and in Central and South America. You can see more photos of this butterfly on this website.
University of Pittsburgh Professor Michael Ramsey turned a former office building into his modern loft, which includes a Japanese Zen garden with a 1,330-pound boulder as its centerpiece. Photo: Laura Petrilla for The Wall Street Journal