For The Answer
By Calvin R. Finch, PhD, SAWS
Conservation Director, and Horticulturist
Week of October 24, 2005
“Less Water Needed”
Now that shorter days, some rain, and cool weather has arrived, there are several good reasons why to reduce watering the lawn.
· The lawn does not need the water. In the autumn, grass growth is reduced in reaction to shorter days and cooler temperatures. The moisture that is in the soil now, is plenty for the lawn.
· Autumn is brown patch fungus time. The disease infects over-watered lawns. During rainy weather it may even attack lawns that are not irrigated. The disease starts in low wet spots and can spread throughout the lawn. A fungicide like F-Stop, Turfcide, or Fungaway will stop the spread of brown patch, but the best treatment is prevention. The most effective way to prevent the disease is to stop watering the lawn.
· Water for the lawn is relatively expensive. It does not make sense to irrigate when the lawn does not need the water. Beginning next month, SAWS and other water companies begin establishing their sewer rates for 2006. Your rate is determined by winter water use. Unnecessary lawn watering for November through February cost you more than just the current water charges.
In addition to being time to stop watering the lawn, it is time to apply a “winterizer” fertilizer. The appropriate fertilizers have the term winterizer somewhere on the bag. The best have a 3-1-2 ratio of nutrients. A common formula is 18-6-12. The formula means the bag contains approximately 18% nitrogen, 6% phosphorous, and 12% potassium. Apply about one pound of nitrogen per 1,000 sq. ft. The instructions on the bag will tell you which setting to use on your fertilizer spreader. If it doesn’t, use the second most restrictive setting.
This time of the year lawns have quit growing at the high rate they did during spring and summer. The fertilizer you apply now will be used to cope with cold weather and will be stored so the lawn can green up quickly next spring. Some horticulturists believe the fall fertilization is the most important of the year for overall lawn health.
I normally recommend that a winter pre-emergent herbicide be applied in September if you hope to prevent winter weeds like dandelions, bedstraw, annual bluegrass, thistles, and henbit. This year, however, was so hot until two weeks ago; if you apply a pre-emergent herbicide this week you will probably prevent most winter weeds.
For organic gardeners the corn gluten works best as an herbicide when it is applied just as the weeds for the season begin to germinate. Now, may be the time.
The crabgrass, and other summer annual weeds will die no matter what you do, so in most cases it does not make sense to waste a herbicide on them. The exceptions may be perennials like Bermuda grass and nutshedge. They are particularly susceptible to contact herbicides over the next month. Use Round-up or a grass killer (Vantage, Grass-be-Gone, Over the Top, Fusilade and others) for Bermuda grass. For nutshedge, use Image or Manage. Kill these weeds now and they will be less of a problem next spring.