Q. My Chinese Pistache was planted in my xeriscape front yard almost 4 years ago. Overall, I’d say it’s doing fine. One thing puzzling is that the leaves started changing to “fall colors” around the beginning of August. I don’t remember when it changed colors last or previous years but I think that’s a bit soon. Again, the tree looks healthy to me but I thought I’d check with you to see if I should be concerned.
A. I agree, August is early in our climate unless there had been some unusually cold weather. Early fall color can be a sign of plant stress and this would be followed by unusually early leaf drop. The usual reason for this type of stress is either a lack of water or possibly watering too often.
|Pistache with fall color.|
When watering, give the plant a lot of water all at once so the water drains to a depth of 2 feet, wetting all the roots. This will require that there are enough drip emitters and they deliver enough water if you are using drip.
Chinese Pistache trees can get large, 40 feet, and the larger they get the more water they will need. Increase the amount of water they receive by adding more emitters every few years. It also helps if this tree has other plants growing around it that are receiving water.
Do not water this tree daily. That is a big no-no. Watering deep, twice a week, would be plenty.
Chinese Pistache will survive lawns but the soil under lawns is usually much better than the soil under rock mulch. When they are growing in lawns, this soil can be much more forgiving than the soil under a rock mulch that is getting watered too often.
Chinese Pistache typically does not have a lot of insect or disease problems in our area so I would tend to think that this would not be the case unless of course you are watering frequently. This will cause big problems for this tree in the future.