Despite desert climate, lilacs can survive here

     By Bob Morris
     View columnist
      The following are issues our Master Gardeners deal with daily at the Nevada Cooperative Extension. If you have gardening questions, call the Master Gardeners' hot line at 257-5555 between 9 a.m. and 4 p.m. Monday through Friday, or send an e-mail to ExtremeHort @aol.com.
     
      Q: I moved to Las Vegas in 1991 from New York and I really miss the lilacs in the spring. Recently, I met a man at church with a stem of lilacs he said he picked from his tree here in the city. He said he brought back a clipping from back East years ago and has transplanted it in his yard. Will lilacs grow in our desert environment?
      A: Yes, some lilacs will grow here, but others have a rough time of it. You have to pick the right variety that requires less chilling hours than others.
      There are hundreds of varieties and even a couple of different species. Lavender Lady hybrid has been successful here, but I'm sure there are others.
      Check out the Persian lilacs as an alternative to common lilacs. They seem to do better in our climate. I would contact your local nursery and see which varieties they carry.
      Question: My lawn (fescue) is suddenly developing a 3-foot by 5-foot brown area. There has been no change in the water regime or any other discernible factor. What's up?
      Answer: Tough call. If it's insects, then the grass should pull up easily in your hands if it's freshly killed. Insects usually don't kill in large areas like that; they are more random.
      Most insects cut off grass at or just below the soil level, and disease is rather unlikely this time of year. Most of the problems I have seen so far are just a lack of deep watering.
      Soils are very dry this year in many places. Push a screwdriver in these areas 10 to 12 inches deep and see if you can reach wet soil.
      This sounds like something was done to this area, and it's not insects or disease. This could be things like fertilizer spills, gasoline spills, something lying on the lawn such as clear plastic when the sun was shining, that sort of thing.
      Q: I planted some spreading junipers along our imitation dry riverbed and a couple of them were starting to look as if they were dying. Upon closer inspection, I found they had turned sort of grayish and had a fine webbing material affixed to them, much like a spider web or possibly a mold. Is this a problem?
      A: The gray-green color, if it was originally a healthy dark green, is a sign that the plant may be dead.
      One way to check to see if it's dead is to grab one of the branches in both hands and bend it to a 90-degree angle.
      If it's dead then the branch will snap. If it's still alive, the branch will be flexible enough to not be hurt. If it's dead then you should remove it and reconsider planting another plant in that hole until you read further. There are several things that can go wrong with junipers.
      The first and probably most common is root rot from overwatering. Although these are not plants suitable for pure desert landscapes, they can be relatively low in their water use.
      They also are very sensitive to soils that are kept wet. They prefer soils that are wet then dry and then wet again. In other words, the roots need a chance to dry out between waterings -- but not too dry.
      True desert plants can usually tolerate wet soils and then very dry soils because they have the means to stay alive during prolonged drought.
      If junipers are kept constantly wet, they will die. At the same time, if they are kept dry for long periods, they can die. A happy medium has to be found.
      They would do well on the same irrigation cycle as trees and shrubs but not flowers or lawns. If the juniper died of too much water and you want to replace it with another juniper, I would dig the soil out of that hole where the roots were to a depth maybe 6 or 10 inches below the old roots and out a foot to the sides and replace it with fresh soil.
      It's possible the root rot disease that killed it if it was over-watered is still in the soil and will do the same to a new plant. Use peat moss in the backfill of the new plant and also use garden sulfur.
      Peat moss is excellent for helping prevent recurring root rot diseases, and sulfur seems to help as well. The sulfur should be very finely milled for a quick reaction.The webbing may or may not indicate a different problem.
      Webbing can sometimes indicate spider mites, which can be a problem on junipers. But it can also indicate just plain old spiders, which actually could be good guys for your landscape.
      To find out if these are spider mites, take one branch and sap it pretty hard against a pure white piece of standard sized paper. After doing that, hold the paper very still for at least 10 seconds and look at it very closely. Spider mites are very small relatives to spiders, the size of a dot made on a piece of paper by a sharp pencil.
      They do, at certain times of their lives, make a very fine webbing in plants they attack. In large numbers, they will kill a plant like a juniper.
      If you have spider mites, you will probably see some very small dots moving on your paper. If you smear these dots and they are spider mites they will probably leave a rusty red smudge on the paper.
      Control is relatively easy by first washing the plants regularly with a stream of water to remove dust that interferes with their predators. Next you can try insecticidal soaps on a regular basis or horticultural oils when the weather is cool.
      As a last resort, you can use a chemical miticide purchased from a nursery or garden center.
      Q: I have this white alkali that comes out of the ground this time of year. It climbs up the hollow block wall and deteriorates the rock in the desert landscape. I do not think it is doing the trees and rose bushes any good. What can I use to neutralize it? And will it keep it from coming back every year?
      A: The best thing you can do is to get water away from the block wall.
      The water is either wicking up from the soil, evaporating from the wall and leaving a salt deposit behind, or water is hitting the block from a sprinkler system.
      Either way, the only solution I can think of is to get the water away from the walls.
      Q: I have a back yard which has been landscaped with a lawn and some fruit and flower trees. I fertilized the lawn and trees two weeks ago. I used Gro Power (5-3-1 with humus) sprinkling it on the lawn and around the trees
      The trees seem to be doing fine but the grass on the lawn appears to have patches of brown grass. What is your advice as to what I should do to the brown patches? Also, when should I fertilize again, and what is the best fertilizer to use?
      A: It sounds like you may have bermudagrass in those spots if the lawn has been neglected. Bermudagrass is a warm-season grass, so it doesn't really get green here until another month or so.
      If you want to get rid of the bermudagrass and stay with the other green grass, then it would be best to wait until fall and spray a herbicide such as Roundup to kill the existing bermudagrass and then seed whatever grass you want to use in the fall.
      You would have to wait about seven to 10 days after you spray to reseed in the area you sprayed. If you want to keep the bermudagrass, you would spray the green grass you have and kill it out and install bermudagrass where the green grass is located. We have some fact sheets that will cover this information for you.
     
     Bob Morris is a horticulture specialist with Nevada Cooperative Extension.