Q.brown leaves on top of my young Joshua tree
The top of my four foot Joshua tree that is planted outdoors is turning brownish-yellow. It is planted in the desert, where I reside. There are several arms, but only one seems to be affected. We are going through a heat wave presently. I am watering twice a week, 4 minutes at a time. I cannot tell you how many gallons per minute is being given, but the soil is damp. There hasn’t been any reside water sitting in the “tree well.” Should I add more days of watering?
Joshua trees are very drought tolerant. If the soil is remaining moist too long you are probably overwatering. They need very well draining sandy soil. If you think about the Joshua trees in wild spaces they rely only on the rain they receive each year. This year we have had an excessive amount of rain in San Diego. I don't know if it is the same where you are. I would check the tip that is turning brownish yellow to see if it appears soft and rotting. If it is rotting you may want to remove the limb so the tissue rot doesn't spread to other areas of the plant. Cut well below the damage into healthy tissue. I don't know if it will grow a new tip. As with any pruning, clean your pruners/saw in a solution of bleach and water to remove any chance of spreading disease on your next cut/prune.