Question
we live in germany and have 2 of these trees, they are about 5 years old, the flower were out this year and now the leaves are turning yellow and falling, need to know what could be the cause.

Thanks Al

Answer
Dear Al, There are several things that could be wrong with your princess trees, so let me go through them and you can decide which problem is affecting your trees.  First, the leaves could be yellow and falling because it is not getting enough water.  Is the climate drier than in recent years?  Or is it much wetter than usual?  Either too much water or too little water is the most likely cause of yellow falling leaves.  If it is too dry, then water the trees at a medium drip from a garden hose for about 15 minutes at least once a week.  If the ground is staying too wet, try to dig small trenches around the trees to drain the water away from them.  The next most likely cause of yellow leaves would be borers.  You would see small holes with perhaps a sawdust looking material coming out of the holes, or sap oozing down the tree trunk.  If you see borer damage, spray the tree with Spinosad, an organic ingredient that should be available in your area, or spray with any other chemical recommended for borers.  Lastly, the most likely cause for the yellowing leaves would be some kind of damage to the trees.  Look for trees cut by a weedeater line at the base of the tree (to trim around the trees), or any split limbs or damaged limbs that need to be trimmed and removed.  Unfortunately, the princess trees are very fast growing, which sometimes causes them to have weak wood, so it is important that they are checked for split limbs from time to time, which should be removed and covered with pruning paint.  Without a picture, and sometimes with a picture, it is often hard to be sure what exactly is wrong with a plant without looking carefully around it and trying to pinpoint the problem.  I think the most likely cause of the leaves dropping is that it needs more water, so check that first.  Please write back if you are unable to find what is wrong with your trees from these tips.  If the leaves show any spotting before falling, they could be affected with a fungus and need to be sprayed with fungicide.  I hope this information helps.  Good luck, Melissa