Weather change signals time to alter irrigation schedule

      The following are typical questions our Master Gardeners answer 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. There is also a gardening Web site at http://www. intermind.net/mgarden/.
     
      Sprinkler systems for lawns should not be operating every day. Drip or bubblers used for irrigating trees and shrubs should not be operating daily either.
      This is unhealthy for plants. Right now is an excellent time to try increasing the number of days between irrigations as long as possible.
      Try to irrigate lawns only twice a week if possible. Those of you with lawns that have a deep root system will be able to do it. Those without deep root systems should still be able to water only three times each week.
      Root depth for lawns is determined by the type of lawn, type of soil, and how it is managed. Deep, sandy soils with grass that is watered only when needed makes the deepest roots.
      Trees and shrubs should be watered deeply, much deeper than lawns. This would mean that the number of days between irrigations for trees and shrubs is much longer than for lawns.
      To roughly estimate the number of days between irrigations for trees and shrubs, take the number of days between irrigations for lawns and multiply by five.
      For instance, if you are watering twice per week now then you could irrigate trees and shrubs approximately once every two to three weeks.
      In the winter if you are watering the lawn once every week then you should be able to wait five weeks for trees and shrubs. Remember, trees and shrubs are deep watered so they don't need to be watered as often.
      This would not apply to water-conserving landscapes such as Xeriscapes or cacti. Their watering schedules would be longer between irrigations.
      Question: Crickets are a problem for us now that the weather has turned cold. They are coming into our home and garage. Is there anything we can use to keep them out?
      Answer: The traditional way was to spray the entire foundation of the home with a pesticide. The pesticide was sprayed in a band wide enough so that pests had to cross this band to enter into the home. When they did cross this band, they would then come in contact with a deadly poison. That poison would kill them rather quickly.
      If the label rate was followed correctly, the amount of poison was spread out over the area so that only small insects like crickets, ants, roaches, spiders and the like are killed.
      The amount of poison was calibrated so that it was high enough to kill insects but not small animals, pets or people. However, anything that did cross this path came in contact with this poison.
      Bare feet and pads on the bottom of paws are areas of the body that can take up pesticides rapidly. The adage, the dose makes the poison is appropriate here. In many cases, the amount that a pet or human takes in is usually not enough to make them outwardly sick.
      Flu symptoms are nearly identical to a mild, pesticide poisoning. By the way, the testing done with pesticides for toxicity is for acute toxicity or short-term effects of the poison.
      There is very little testing done for long term or chronic effects.
      This means that we have almost no idea what happens with repeated contact over long periods of time. Our office has done some testing with Neem oil, a natural product from trees in India, that shows some promise.
      There are some indications that peppermint oil can act as a repellent. We can provide some alternative products to traditional pesticides if you would like to participate in a testing program.
      Otherwise you would use the traditional products such as diazinon, dursban, synthetic pyrethroids and other products labeled for home pest control.
      Q: Is this a good time to be planting bulbs?
      A: This is a great time to be planting daffodils and crocus and most other bulbs. Your window of opportunity is until December. You want these to produce some roots before it gets too cold. Bulbs that originate from the temperate parts of the world need a cold period to produce flowers.
      This is called vernalization. During vernalization, parts of the bulb that normally would produce leaves change over to produce flowers. The "trigger" that creates this change to flower production is a prolonged drop to low temperatures.
      To produce abundant flowers, some bulbs require cold for longer periods of time than others; much the same way that fruit trees require different amounts of "winter chilling" to produce abundant flowers for fruit. If temperatures are too warm or chilling doesn't occur, flower production will be poor or nonexistent.
      Get the bulbs in now to take advantage of the cold weather. Don't leave them around the house and plant them in the spring.
      Q: I have worms coming up all over the lawn. I don't mind worms but there are just too many and it looks messy. Can they be controlled?
      A: I wish you would reconsider trying to control them and be a bit more accepting of the messiness they are creating. Worms that come to the surface of a lawn is a good and healthy sign.
      They indicate that there is activity going on that is working to your lawn's benefit. As one of our Master Gardeners told me, you're getting a free lawn aeration.
      That's a key in trying to solve your lawn's problem. If the worms are tunneling holes to the surface of your lawn, then help them. Purchase a hand aerator at any of the nursery or garden centers and aerate the lawn in the areas where the earthworms are a problem.
      What you don't want to do is try and kill them or reduce their numbers. Watering also plays a role. Worms need air to breathe.
      Soil is made of spaces or voids that can hold either air or water. Whenever air spaces are continually filled with water, more room for air is needed.
      Worms tunnel to the surface to create more spaces for air. Try and adjust your lawn watering so that the lawn dries between irrigations. This is a perfect time of year to really cut back on irrigations. The plants and your wallet will benefit.
      Q: I have those white butterflies flying around my cabbage plants. I'm fairly sure that they are those insects that eat cabbage. What should I use to control them?
      A: Those are probably the cabbage loopers. They are a perfect candidate for using a Bt spray. Bt is short for the scientific name for a bacterium. This bacterium provides a natural means of pest control that works on cabbage looper and other caterpillars.
      It is selective on only those caterpillars that develop into moths and butterflies. Keep in mind that this product does not selectively work on just this insect but will kill many caterpillars in this category.
      This could include caterpillars that turn into beautiful butterflies as well. So this might not be the best pesticide to use everywhere in your yard if you had plants that attracted butterflies for your enjoyment. It's safe for you because you aren't a moth or butterfly. Use this product selectively in a very restricted area of your garden.
      Trade names include Dipel and Thuricide, among others. Read the label to make sure you pick the right Bt for this job. We now have available to us several different Bt sprays or dusts that were specifically produced to control insects other than moths or butterflies.
      Q: I am changing out my hot water heater and I don't want to waste the water in the tank. Can I use this water to water my plants or is this water not good to use? I do have a water softener as well.
      A: I would not use it. Many people have chosen to have all of the water in the home softened to reduce lime deposits after washing. If you have a water softener, it is not safe to use any water connected to the softener for watering plants.
      The problem with the traditional salts used for softening water is the sodium content. Sodium is very destructive to soils used for growing plants. Repeated use of this type of water will destroy a soil's structure and workability. Sodium is also a very toxic mineral to most plants.
      With continued watering from softened water, most plants will be damaged. Be careful with hose bibs that come from inside the house. These may not be safe places for you to use for irrigating plants.
      Don't use these hose bibs for a garden hose or drip irrigation connection for vegetables or fruit. It would be best to have a hose bib connection coming directly from the pressurized side of your irrigation system and use this for watering.
     
     Bob Morris is a horticulture specialist with Nevada Cooperative Extension.