Determining nutrient deficiencies in turf takes a thorough understanding of the biotic and abiotic factors that can damage and discolor it.
No one likes it when brown patches cause unsightly blemishes in a perfect stand of turf. Effective turfgrass management involves finding out if the origin of these sometimes sudden and usually troublesome imperfections is a nutrition problem or something else.
Just like any plant, various factors or agents can stunt turf growth and, as a result, negatively impact its appearance and strength. These outside pressures usually fall into two categories: biotic (living) or abiotic (non-living).
Determining which agent is causing turf symptoms, however, can be challenging. According to the University of Georgia’s College of Agricultural and Environmental Sciences, proper diagnosis of turf problems “requires thorough examination of the site, knowledge of relevant past and present environmental conditions, in-depth knowledge of plant species biology, site management history and an orderly series of tests to determine possible causes.”
Basics of Biotics
Living organisms, such as fungi or insects, cause biotic turfgrass disorders. Most biotic agents damage turf by causing stress or killing cells. Just because one area shows symptoms, though, doesn’t always mean the problem causing them resides there. For instance, a root rot can cause yellowing and wilting in the turfstand. This is why examining the entire plant is important when seeking the cause of symptoms.
In most cases, a healthy lawn is the best defense against biotic agents. Just as a person with a weakened immune system is more susceptible to colds and flus, a weak plant is more susceptible to insect and disease infestation. This is where good plant nutrition comes in-without it, strong plants would not have the nutritional building blocks they need to fight off disease and withstand insect attacks.
Abiotic plant disorders develop due to non-living factors, such as weather, soils, chemicals or mechanical injuries. They can result from a single extreme environmental event, such as a severe storm or extreme cold snap or flooding, or from chronic conditions, such as prolonged drought or a turf species placed in an inappropriate location.
One of the major causes of abiotic plant disorders is improper water application, says Colorado State University research. “Too much water can be just as damaging as not enough water, since both kill roots,” the study says.
Assessment and Diagnosis
Several factors, both biotic and abiotic, contribute to turf health problems so managers often have to dig deep for clues and answers. To shorten the list of problems causing an unhealthy lawn, university researchers and turfgrass experts recommend the following steps:
- Step 1: Assess the situation. Does the entire lawn have a problem or just one spot? Look for symptoms (yellowing or brown turf), as well as signs (insects).
- Step 2: Ask questions about recent and past events. What maintenance has been done? What has the weather been like?
- Step 3: Consider soil testing or the help of a plant diagnostic laboratory.
- Step 4: Look closely at your fertility program. Is it still effective or does it need some adjustments?