Expert: David Date: 5/15/2008 Subject: Crapemyrtle problem?
Question We have a crapemyrtle that was planted by the developer when we bought or home in Dec. '06. I don't know the particular type but it is a young tree about 9 feet tall. I think the flowers last year were either purple or red, but I am not sure. It has just developed snow white tips on some of the newer leaves that rob off. I sprayed it with a spray for mildews, etc. that I was using for my rose bushes to treat mildew on them as they were displaying signs of a white mildew. I don't know if this condition is due to a fungus, a pest or my imagination. We live just inside the Texas Hill Country northerly of San Antonio and have about 4-6 ins. of topsoil over limestone and have good drainage in the area. I water the area by automatic sprinkler for 15 mins. twice a week and it is in a mulched flower bed.
We also have a hybrid oak (3" diameter trunk) that has the tips of the newer leaves browning after about 3 weeks. Can you advise as to whether I have a problem or not?
Answer As far as the crape myrtle, it sounds like powdery mildew. You will need to spray a fungicide avery 10-14 days to prevent this fungus from destroying the flower potential of the plant. Wettable sulfur works well against powdery mildew but cannot be sprayed during periods of over 90 F, or phytotoxicity may occur. Continue to use the powdery mildew product you are using for the roses at this point and wait a couple of weeks to see if the new growth is growing normally. If not, repsond back to me and I can provide other alternative products for mildew control. Discontinue the automated sprinkler in that region as the overhead water spreads the rose and crape myrtle fungal spores around. Water by hand and do it on the soil surface without contacting the foliage.
The oak may have transplant shock and I wouldnt worry to much at this point. Make sure it is watered properly and fertilize with a slow release tree fertilizer. Wait a couple of weeks and let me know how it is doing as well. Good Luck.
