For:
By: Daniel E. Mullins
Extension Horticulture Agent
Heavy Rains Are Helping Some Lawns and Hurting Others
How is the lawn grass looking after receiving three weeks of daily rains? There appear to be two extremes. Some lawns are looking better than ever, while others are in decline.
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So why would some lawns respond positively to the wet weather, while others have expanding dead spots? Mostly, the result has to do with the irrigation practices prior to this wet period as well as internal and surface drainage.
A lawn that looks better during rainy spells indicates that irrigation was not adequate during previous dry periods. With some exceptions, most homeowners tend to water too lightly and too often.
Daily watering should never be done on a home lawn once it is established. Such a practice results in a shallow weak root system and provides ideal conditions for various diseases. Think deeply, but infrequently when watering.
How often should I water? This is the most frequent lawn irrigation question. There is no one answer that fits everyone’s situation. It depends upon the soil texture, condition of the grass roots, kind of grass, the fertilization program and other factors.
The recommended watering frequency can vary from once a week to three times per week, depending upon seasonal conditions. We recommend watering “as needed,” rather than on a schedule.
There are three ways to determine if it is time to water the lawn. When wilted spots begin to show – these are those gray blotches that show up most during mid-afternoon; when you can walk across the lawn and see the imprint of your shoes and when the grass blades fold in half.
Watering too little during each application is a common mistake. The typical lawn should receive one-half to three-fourths surface inch of water per application. Which leads to the second most common question – how long should I run my sprinklers?
The length of time that sprinklers should be run depends upon the system’s pipe size, pressure and sprinkler heads that were installed. No two are exactly the same, so the required time would be different.
Do the “pan test” to determine the amount of time required to apply the needed one-half to three-fourth of an inch of water. Place five or six straight – sided pans at random within the area to be irrigated. While making note of the time, run the system until an average of one-half to three fourths of an inch of water is collected in the pans.
Lawns that decline during wet weather are often diseased. This occurs most frequently in areas that have poor soil surface or internal drainage. Soil that is saturated for long periods results in root death and invites infection by several fungal species.
The decline during wet weather should be diagnosed prior to taking control measures. In some cases extremely wet areas should be corrected by adding soil or altering the drainage pattern. In other cases, fungicide applications are necessary to arrest the disease before serious lawn damage occurs.
Question of the Week: Whiteflies are infesting my citrus trees and I plan to use an oil spray for control. Is this okay?
Answer: Little insect control is required on most home grown citrus plants as several beneficial insects help to keep these pests under control. When severe whitefly infestations occur they can be controlled with spray applications containing insecticidal soap or horticultural oil.
Control the immature whiteflies, as this is the stage that they can cause damage. These nymphs occur on the undersides of leaves, so the spray must contact them in order to obtain control.
If horticultural oil is used be certain to use ultra-fine oil at this time of year. Most other oils should not be used when temperatures are above about 80 degrees F.
Note: Inspect plants and apply control measures only when there are sufficient numbers of immature whiteflies. Attempting to control the flying adults is not practical.