More Leaf Drop in Apricot - Its Hot, Check Irrigation!

Q.  We have an apricot tree about 5 years old.  It’s always seemed happy but this year it leafed out beautifully then last week started losing it’s healthy green leaves on one side.  Apricots are on the tree, but not developed yet. Now half the branches on that one side are leafless.

A. I looked at the picture and it looks like a watering problem; not enough water getting to the upper limbs and causing drought and leaf drop. Drought occurs first on the hottest side, the sides facing the sun. If you remember, we had a hot spell just before the weather cooled off again.

See if the tree is still alive

            Go to your tree and bend the smallest branches to see if they are still supple. For most fruit trees, if this problem is temporary they will be supple and bend easily without breaking. If this is the case, expect the tree to produce more leaves and branches after a couple of weeks if it is given water.

            Following the KISS rationale, we can eliminate the less likely disease problems, a weed killer spray drifting toward the tree, fertilizer misapplications and the like.

            Now, the cause of the drought. Water shortage to these limbs could result from not enough water applied to the tree or in the right areas, or damage to the trunk or limbs by boring insects tunneling through the trunk and limbs and interrupting the flow of water. If sap is not seen on the trunk or branches or the bark is not peeling off, then we can also probably eliminate borers.

Q. When is the best time 

to check fruit trees for borers?

A. The day after it rains.

            Leaf browning and dropping from borer damage usually happens around June or July when it gets hot. But inspect the trunk and limbs anyway for signs of borers.

Water, Water Everywhere

            That leaves us with irrigation, which is the most likely reason particularly because of the unusual weather. A five-year old tree should be pretty big so its water needs are also large unless you have purposely kept it smaller through pruning. A five-year old tree probably needs around 25 to 30 gallons of water each time it is irrigated. This water should be applied to as much area under the canopy as possible.

How Many Emitters?

            The minimum number of emitters needed for a five-year old tree is four; each located about 12 to 18 inches from the trunk in a square pattern surrounding it. Six emitters arranged in a circle 18 inches from the trunk would be even better. Apply the water long enough so it penetrates to about 18 inches deep. I don’t know how many minutes this would be because each irrigation system is different. But keep the number of minutes the same as before and increase the size of the drip emitters instead if the water is not deep enough.

Giving the Tree the Shaft

            To judge if you applied enough water, use a long steel rod, like a three-foot length of rebar, and push it into the wet soil after an irrigation. Do this in about three or four locations to get an average irrigation depth.

            This time of year, water about Three times a week if the soil is covered in woodchips. A thick layer of mulch on top of the wet soil usually saves one or possibly two days between irrigations. In June, water three times a week when it starts to get hot. If you aren’t sure when to irrigate, use a soil moisture meter like those for houseplants, to measure if the soil is dry enough to water again. Don’t trust the surface of the soil to tell you. Push the tip in the soil about 4 to 6 inches deep to get a measurement.