What is take-all root rot, and what are the symptoms?

• Take-all root rot, also known as take-all patch, is a fungal disease most often noticed in St. Augustinegrass lawn, although the fungus also infects bermudagrass and zoysiagrass.• Take-all kills roots and runners, leading to the decline and death of irregularly shaped areas of a lawn.
• Take-all is present in almost any St. Augustine lawn, but its symptoms and damage occur after some type of stress weakens the turf, allowing take-all to overcome the turf’s defenses.
• Stresses that weaken turf include a lack of soil moisture, dense
  shade, soil compaction, high soil pH, excessive pre-emergence herbicide application, and post-emergent broadleaf herbicide applications when temperatures are above the upper 80s.
• Initial symptoms are usually yellowing of the grass, which progresses into browning and death.
• Drought damage and chinch bug damage resemble take-all. Check for chinch bugs in areas where the lawn is starting to decline. Not in areas that are already dead.

4 Steps to Prevent and/or Control Take-All Root Rot (do as many of these as you can, starting with #1):

1) Avoiding stress to the lawn is the most effective way to avoid and manage take-all root rot:

• • Water the lawn deeply and only often enough to maintain moderate soil moisture.
  • Minimizing thatch by avoiding excessive applications of nitrogen. See my Lawn Care Schedule on my website, gardeningwithskip.com.
  • Mow St. Augustine at 2 1/2 to 3 1/2”
  • Don’t apply post-emergence broadleaf herbicides when the temp is above the upper 80s.
    Read the herbicide product’s label for application restrictions.
  • Core aeration helps remedy compaction and promotes turf health.

2) Apply a fungicide containing azoxystrobin in fall and spring (see my Pest, Disease, & Weed Management Schedule). Scott’s DiseaseEX (granules) is the only product with azoxystrobin that I’m aware of in retail outlets. Products containing propiconazole or myclobutanil may also be effective and come in liquid or granular forms. Apply enough liquid through a hose-end sprayer to wet the turf well. All of the above must be watered in with 1/3” of irrigation after applying them.

3) Apply an iron and manganese supplement through a hose-end sprayer to yellowing lawn areas. Repeat as needed to maintain a green turf grass color. Examples include: Fertilome Chelated Iron & Other Micronutrients, Monterey Iron Combo 1-0-2, and Bonide Liquid Iron Complex.

4) Apply peat moss 1/3” deep in spring and fall over the area and water it in with 1/2” of irrigation. (One 3.8 cubic foot bale of peat moss covers 1,000 square feet about 1/3” deep. This provides a temporary suppression.

It is VERY IMPORTANT to respond proactively to this disease because it is MUCH easier to prevent than to “cure” take-all once the damage symptoms begin to appear!

Once dieback has begun, the turfgrass plants lack roots to take up water and nutrients to support growth, so the turf will continue to decline for a while even after control measures have begun.