For The Answer
Calvin R. Finch, Ph.D., Conservation
Manager, San Antonio Water System, and Horticulturist
Q. How much water do old-fashioned roses require? I have tried to grow modern roses, but it is just too difficult with all the pesticides and watering.
A. Old-fashioned roses are tougher than most modern roses. They survive without pesticides and supplemental irrigation. The more care you give them, however, the better they will bloom.
Q. Why do my onion stalks turn milky white? Is it a disease? Are they still usable? The bulbs look good.
A. Thrips are rasping insects that suck juices from blooms and onion stalks. They are the cause of the milky look. The thrip damage does not affect the quality of the bulbs.
Q. Did you and Jerry Parsons resolve the question of whether deer eat pittosporum or not? I think it is entertaining when you disagree. Jerry is rude and you try to stay calm but there is an edge to your voice. How many years have you and Parsons worked together on the radio?
A. Jerry and I agreed to disagree. The deer in my neighborhood do not eat full size pittosporum, but they seem to eat them in other neighborhoods. Dr. Parsons and I have worked together on KLUP for about 4 years (14 years total). He is a great horticulturist who likes to tease and aggravate other folks. I am one of his favorite targets!
Q. Which shade trees do best in sandy soil?
A. The best strategy is to look around and see what is growing well. Texas red oak and live oaks are usually good choices. Add organic material to the planting site and be prepared to water frequently and shallowly for the first year.
Q. My blackberries are done producing. There are dead branches and vigorous new growth. Should I cut out the old growth?
A. Yes, prune out the old growth. The old growth is called floricanes and will die after they produce the fruit. The primocanes (new growth) will produce next years fruit. Prune the primocanes at 36 inches to keep them from taking over your garden.
Q. Carpenter ants are in my trees and even a beam in the house. Are they a threat to the trees and house? How can we control them?
A. Carpenter ants are not a direct threat to trees or homes; they utilize rotted wood and are common in old trees. Kill carpenter ants with borer spray. Read the label closely. In the house, it is best to have an exterminator check to make sure termites are not also present; they will kill both insects. If you think you can do the spraying, seek out a spray labeled for indoor use.