Salt Build Up in Soils

The following is a text message between a friend of mine in California and myself regarding his fruit trees and why the leaves are browning at the tips. If you have similar questions and would like to be featured on this blog, please call, text, email or message me pictures of your trees.

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JB: Do you Know what I can treat my avocado tree with to help with the browning leaves? it has made a lot of the leaves already fall off. It is also happening to my peach and plum trees.

Russ: Lack of water.. I know you are probably thinking. "I water my trees regularly!" So, it's not that you are not watering it enough, it usually means the tree is unable to draw the water up from the roots, and there are at least three things that could cause this.

First, Over watering could cause the roots to rot. Scratch the soil around the base and see if it smells rotten.

Second, nematodes or other soil bound organism attacking the root system. this is nearly impossible for the average back yard gardener to diagnose.

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Third, and most likely...because all of the trees are suffering and because of the time of the year, you probably have salt build up in the soil.

Most water has lots of dissolved minerals that build up over the summer, especially in dry climates or drought conditions. This salt build up will prevent the tree from accessing the water that is present in the ground. Best thing to do is to prevent the build up of salts by minimizing the watering. Sounds like the opposite of what you should do, but it's important to keep the water that you put in the ground, in the ground. Put mulch around the base of the tree, do less often, deeper waterings, amend the soil around the base of the tree with organic matter and use rain water as much as possible. (Collect the water that falls off the roof in large barrels and use that instead of the hose.)

Hope that helps!

For now you can try to push the salts down in the soil by leaving the hose on really low over night. Just make sure it has a chance to dry out before you water it again.

JB: Amend the soil with organic matter? I water it every few days with the hose about 1-2 gallons.

Russ: Get some well aged compost, and spread a 1 inch layer out to the drip line (the farthest edge of the tree's canopy) and use a hand rake to work it into the soil two to three inches deep. It would be better to water the trees ten to twelve gallons once weekly. Depends on the size of the tree though. How big are the peach and plum?

JB: Can I buy the compost at a store? Similar to manure?

Russ: In the picture you sent me of the avocado, make the dish of soil that holds the water twice as wide and fill the entire dish with medium shred bark mulch. For amendment don't use manure! Look for something that says forest compost.You should be able to buy it at the store in bags. Or make your own with leaves and kitchen scraps.

JB: Plum tree hasn't produced anything this year.

Russ: That one looks stressed, like lack of water. The leaves are small and sickly. To conserve water, lots of fruit trees won't fruit. Pull up the grass around the base and build a large shallow dish out to the drip line and fill the dish with mulch.

JB: Peach tree, only produced about 5 small ones and they dropped before they could grow. Both trees are about 7-8 feet tall.

Russ: The Peach looks good with water, I would move those blocks, mulch and thin the branches. Looks like you lost some big branches in the past. The plum and peach need a good pruning. Should be done in the winter.

JB: It was before I moved to this address. The blocks are holding the tortoises shelter up. Ok, so I need to prune this winter.

Russ: Correct

JB: Ok thanks I'll probably get a hold of you later for help with that. Thanks Russ!

Russ: Any time!

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