African Sumac And Leaf Drop

 Q. I have an African sumac in my backyard that has leaves which turn brown and fall off.  I have one in my front yard that does not do that.  The one in the back is close to grass which gets 5 minutes of water three times a day.  The one in the front is in a rock landscape and gets a lot less water.  Is this a natural for them or is it getting too much water or not enough fertilizer?  The backyard one is on the east side and the one in the front faces west which is very hot.  The one in the back is about 15 years old and about 35 feet tall and wide.  Any help would be great.

A. Sometimes they can get so dense that internal shading of the canopy will cause leaves to die and drop. These are fairly messy trees due to leaf drop and dropping of their berries. If the tree in the drier landscape is more open and the tree in the back is more dense then this can be the reason.

Other reasons might include pest problems such as aphids which can cause the leaves to be sticky or shiny and leaf drop if there are in large numbers.  If the leaves are sticky, try spraying with repeat applications of soap and water or insecticidal soaps.  Aphids should disappear during hot weather but reappear again during cool weather.  You may also see a lot of ant activity that are working off of the aphids sugary honeydew droppings.

You can try to open up the canopy with some branch removal (thinning of the canopy by selective limb removal) and admit more light inside the canopy. This however will probably cause some suckering on the limbs if too many limbs are removed.

Another possibility could be overwatering. If the tree is watered too often it is possible to develop root rots and lead drop will occur and usually branch dieback.