Ask the Expert: Avocado tree question.

Hi all, I have a well established (~10-20 yrs old) which has produced avocados the last 6 years. This year, no fruit and the top 1/3 of the trees canopy has turned brown. I have no idea what is happening. I water the tree every other day for ten minutes. I have also noted splits in the bark at the base of the trunk. Does anyone have any ideas or suggestions? Attached is a photo of the leaves. This problem began after our gardener removed the ground cover around the tree earlier this spring. The tree initially looked stressed but began to rebound after a few months. Now the current situation appears to be worsening again. – Art G

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Flower Shop Network‘s Plant Expert’s Reply:

Art, there are several reasons that could cause your avocado tree’s leaves to turn brown. This is a hard diagnosis without knowing the previous conditions of your tree’s environment.

1. Overexposure to the Elements – Harsh conditions could be the reason your avocado tree is turning brown. Overexposure to the following could be the problem:

• Sun
• Ice
• Frost
• Drying Winds
• Salt (carried in the air)

2. Changes in Soil – You mentioned your gardener removed the ground cover around the tree. This loss of mulch could have quite an impact. The ground cover helps retain water for the roots by keeping it from evaporating. When watering, it’s best to water thoroughly then wait until the ground is dry before watering again. A good rule is about 5 gallons twice a week. The best way to do this is by using a 5 gallon bucket with a 1/4″ hole in the center of the bottom. Fill up your bucket and set it a couple of feet away from the trunk of your tree, so that the water oozes across the feeder roots.

3. Root diseases – Root diseases kill or weaken the roots of trees. There is no cure for these, although improved conditions may help the tree to bounce back to normal and outgrow the disorder.

4. Insect Damage – Take a close look at the branches and trunk of your tree. If you notice insect damage or see ants crawling over your tree, this could be a sign of borers. If so, you will need an insecticide to kill the borers in time to heal the tree.

So what to do?

Well, it depends on how far the dieback has progressed. If the brown is just on your leaves then your tree will probably be fine. Keep it well-watered and it should bounce back. It is a good idea to get your soil tested to see if it needs any additional nutrients.

If your branches and trunk are browning, you’re going to have to do some rescuing. Find out exactly how far your tree’s dieback has progressed. Cut into the wood just a bit to see where your tree’s brown turns into fresh green. You’re going to need to cut everything dead off at this point. It’s tough love, but someone’s got to do it!

Before you go hacking off half of your tree, visit your local garden center or contact your extension service for a true diagnosis of your tree. We do the best we can with a description and a photo, but you need to be sure before taking any drastic measures.

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