Last week, I was visiting one of my favorite clients when I noticed that one of her citrus trees was showing signs of sunburn, which led to me explaining to her that even citrus trees need sunscreen to prevent sunburn in many cases.

You can see the lighter-colored bark and some cracks as well along the branch. It turns out that citrus trees are very susceptible to sunburn.
 
So, why is a sunburned citrus tree something to be worried about?
 
Well, when a tree becomes sunburned, it often forms cracks in the bark and within these cracks, damaging insects or fungus can find a nice home.  Frost damage can also cause cracks in the bark.
 
In recent years, I have had to deliver bad news to people whose citrus trees became infected with sooty canker, which is a fungal disease that affects the branches and trunks, which takes root underneath the cracked, flaky bark.
 
 
Several times, I have had to tell homeowners that their much-loved citrus tree was badly infected with sooty canker and had to be removed.  You can read more about the signs and treatment of sooty canker, here.
 
Thankfully, there are things we can do to reduce or eliminate the chance of sunburn to our citrus trees.
 
 
1. Allow citrus trees to grow their lower branches. They will help to shade the trunk.  A bonus for citrus trees grown this way is that the most fruit is produced on the lower branches that also tastes sweeter.
 
 
2. Protect exposed trunks and branches by using citrus paint (available at your local nursery) or by simply mixing white latex paint water so that the resulting mixture is 1/2 paint and 1/2 water. You can also purchase tree wraps made from burlap, which can also help to protect them. Avoid using oil-based paint. 
However, if you allow the lower branches of your citrus tree to grow and the trunk is shaded, than you don’t have to paint them. 
3. Don’t over-prune your citrus trees.  The photo above, is an EXTREME example of what not to do.
 
Citrus trees should be pruned in March, and concentrated on removing dead, diseased or crossing branches.  Avoid pruning more then 20% of its foliage in any given year.  *Remember, that the leaves make food for the tree, which will in turn, produce delicious fruit. If pruning leaves you with exposed branches, then coat them with citrus paint.
**See how to protect citrus from the damaging effects of a heat wave – here.
 
I always wear sunscreen whenever I venture outdoors.  Years spent in California at the beach as a teenager, trying to tan my fair skin did not work.  Now, I try very hard to protect my skin from the desert sun.  I do however, often forget to wear my hat as it does mess up my hair 😉
 
So, do your citrus tree a favor and make sure it is protected from the sun – either by its branches or by ‘sunscreen’.
Noelle Johnson, aka, 'AZ Plant Lady' is a horticulturist, certified arborist, and landscape consultant who helps people learn how to create, grow, and maintain beautiful desert gardens that thrive in a hot, dry climate. She does this through her consulting services, her online class Desert Gardening 101, and her monthly membership club, Through the Garden Gate. As she likes to tell desert-dwellers, "Gardening in the desert isn't hard, but it is different."

11 replies
  1. Jarred
    Jarred says:

    I have a row of 15 sour orange trees as a hedge that has become a little too wide can they be trimmed back again. I worried because it seems like a lot of the leaves would be removed during this process and there isn’t a lot of growth underneath the outer layer of the leaves.

    Reply
    • arizonaplantlady@gmail.com
      arizonaplantlady@gmail.com says:

      Hello Jarred,

      Citrus trees, including sour orange do best when pruned in spring. Pruning in summer is quite stressful for them. My recommendation is to wait until March to prune out the dead branches and then prune back the live growth. It’s important to note that you shouldn’t remove more than 20% of the live growth in a year or you can cause major problems. I recommend contacting a certified arborist, who can help you in pruning your sour orange trees correctly. I hope this helps!

      Reply
  2. PV Peterson
    PV Peterson says:

    My gardener went crazy and pruned back my tangerine tree severely in July. Now the new growth is curling and doesn’t look good. I painted the trunk and branches hoping to prevent sunburn. Is the tree in danger of dying. Help!

    Reply
    • arizonaplantlady@gmail.com
      arizonaplantlady@gmail.com says:

      Hello,

      I’m sorry to hear about your tangerine tree. The new growth is likely responding to having to grow in the intense heat of summer. If the tree is small enough, I would put shade cloth over it to help protect it from the sun until mid-October. I don’t believe it’s time to throw in the towel yet, though. Wait until spring, to see if the cooler temperatures allow it to re-grow normal leaves. I hope that it makes it. 🙂

      Reply
  3. john marcum
    john marcum says:

    Grapefruit tree is about 35 to 40 years old, last summer it started getting very bad sunburn in the limbs and lots of dead leaf droppings, I used. a can of white vinyl latex tree trunk paint to paint the limbs and bark, had a very good recovery, this year how ever the sun is very strong and burning the limbs again, I bought a new can of tree trunk paint and notice that it had a warning that it contained crystalline silica, the older can had no warning, Just curious if this gets absorbed into the fruit, or does this chemical break down and not absorbed into the fruit?

    Reply
    • arizonaplantlady@gmail.com
      arizonaplantlady@gmail.com says:

      Hi john,

      I’m not exactly sure what the answer is. I know that regular latex paint, mixed with one part water is what the experts recommend, but am not sore about the crystal silica. Regardless, I don’t advise using spray paint since you can mix it with water, as recommended. You can always buy ready mixed citrus paint at the nursery.

      Reply

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *