Investigating Problem Turfs

Allen D. Owings, Koske, Thomas J.  |  4/23/2005 12:13:12 AM

Thin and irregular places often indicate a root problem.

Sometimes you must look at what's below.

Turf problems can be categorized as cultural (manmade), environmental or pest-related. Often two or more of these factors contribute to the problem.
For example, a grass that has limited shade tolerance (environmental stress) should not be mowed too low (cultural). Likewise, a nitrogen deficiency (cultural) can be a contributing factor to an outbreak of dollar spot disease (fungal pest) or we might find shade (environmental) and overfertilization (cultural) can promote leaf spot (fungal pest).  When two or more factors contribute to the problem, all factors must be identified before it can be corrected.

Cultural problems are created and are often the most difficult to identify. One of the most common cultural problems is improper irrigation. Light, frequent irrigation on mature sod encourages a never-ending cycle like shallow rooting, algae and soil compaction. When applying a chemical to any turf area, and particularly when trying new materials or trying to solve a problem, place a small 24-inch square cover on the turf to prevent an area from being treated. You now have an area to compare with; you might be surprised by what does and does not work.

Environmental problems include soil conditions (acidity, alkalinity, salinity, poor physical conditions and dry spots), drought, shade, winterkill, heat stress and combinations of these conditions. Characteristics such as sod deterioration, localized dry spots, chlorosis, desiccation, foot printing and scald may occur where environmental conditions are not favorable. Often the factors that cause the problem are not apparent when the symptoms are observed, and the turf manager must depend on records to identify the problem. Drought stress, winterkill and scald are all caused by temporary environmental conditions that may not exist when the damage is most apparent.

Assess the site. Notice drainage and irrigation patterns, soil types and differences, shade patterns for the season, traffic patterns, historical problems, elevations or depressions. Dig in and see what is under the surface; there may be layering or a builder’s pile.

Soil compaction is often referred to as a "hidden" stress because in most instances reduced plant activity is not noticeable; however, soil compaction influences soil aeration and
drainage, plant and soil moisture relationships and soil temperature. It restricts the root development and its normal functions.

Pest problems are only one factor contributing to a poor situation. They may not be the problem; they may be the symptom. Knotweed (Polygonurn), Annual bluegrass, Pathrush and Goosegrass are often a symptom of soil compaction. They, among others, are often referred to as ‘indicator weeds’ because they come in under certain conditions and indicate that those conditions may well be there. Many diseases don't become serious until moisture or other stress is a factor. Turf diseases occur because of a combination of a susceptible host, virulent pathogen and environmental conditions favorable for disease development. Stress may turn on this first component. Turfgrass diseases can be difficult to identify because environmental conditions can modify the visual symptoms.

Once the cause of the problem has been determined, decide if control measures are justified based on economics (practicality) and the severity of the problem. Choose the safest and most effective control measures because chil
dren and pets may be involved. Such measures include the use of adapted grasses, changes in the management program and the use of appropriate chemicals. If chemical control is necessary, select an effective pesticide as recommended by the LSU AgCenter. Read and follow label directions for application.

Keep good records. They help with diagnosis and may save a turf manager's job.
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