Neil Sperry

A new approach to the annoying lawn disease ‘take all root rot’

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Learn a simple, add-as-you-go strategy for building a backyard oasis.

When I was a kid growing up in College Station I read in the garden section of the Houston Post about a “new” insect that was moving out of grain fields and into St. Augustine lawns. They were called chinch bugs, and before I knew it the pests were showing up in the lawns I was mowing.

I moved away to get a couple of degrees from Ohio State and then moved back to Texas just in time to hear about St. Augustine decline (SAD), a virus that was killing lawns in South Texas and making its way northward very quickly. By the mid-1970s it was in DFW and we soon lost most of our St. Augustine turf. But new types were developed that brought resistance.

White grub worms were devouring North Texas lawns, both St. Augustine and bermuda, about that same time. They’re the larval forms of common June beetles, and they were causing entire city blocks of grass to be lost. Insecticides and changes in life patterns of the insects got us through that crisis, and I’ve not seen grubs return to those horrific levels since.

Somewhere along the line brown patch became a fall issue, albeit not of the same concern as the rest. It’s easy enough to stop, plus it only kills leaf blades, not the runners or roots.

I ran into problems with my own St. Augustine in the early ‘90s. It was yellowish all summer, and applying nitrogen only seemed to make things worse. My childhood friend, turf specialist Dr. James McAfee of Texas A&M, told me it was the gray leaf spot fungus and that hot weather and nitrogen would make it much worse. I couldn’t control the temperature, but I learned to quit feeding my St. Augustine between mid-June and early September. My gray leaf spot problems were ended.

Enter the newcomer…

Then, somewhere in the late 1990s, along came a new disease that affects not only St. Augustine but also zoysia and even bermuda. Its ominous name tells its story well: “take all root rot.” You might say that it leaves no roots behind.

But long before you notice the fact that the grass has few vigorous, white roots, you see that it’s not greening up uniformly. Washes of yellowed grass speckle the lawn, and spring feedings do little or nothing to bring things along.

Dr. Phil Colbaugh worked for the Texas Agricultural Experiment Station of Texas A&M in Dallas at the time that TARR was revving its engines. Phil and I worked together for several years and I respected his research greatly, but I have to admit that I found his first recommendations for dealing with TARR rather unusual. He said that existing fungicides were offering no real help. Noting that TARR was primarily a problem in the highly alkaline soils of the I-35 corridor, he had found that application of a 1-inch layer of sphagnum peat moss across infected areas would create an acidic layer sufficient to suppress the fungus. Word of that remedy got out and peat sales skyrocketed. And lawns grew greener.

Colbaugh has continued his fine research. Knowing that, I checked in with him a few days ago. He told me that one fungicide, Azoxystrobin, has shown really good results in stopping TARR even after turf is already involved with the disease. I went over it with him a couple of times to be sure I had my facts straight. Azoxystrobin is the better choice to treat existing TARR and to protect turf that has had it in the past. Sphagnum peat is only effective in suppressing TARR before the grass is fully involved. He told me that I had the order down right.

So with those facts in hand, I’m prepared to suggest that if you have had issues with TARR in recent springs (or last fall) and if you are seeing the early signs of yellowing patches with blackened, foreshortened roots, it’s probably time to treat with Azoxystrobin. If you have a lawn care service working for you, they’re probably going to recognize the trade name “Heritage.” That’s the commercial product containing that active ingredient. At the consumer level, the only product you’ll find in hardware stores, perhaps nurseries and in some national chains will be Scott’s Disease-EX.

Take all root rot is primarily a cool-season spring disease. As temperatures rise in late May and on into June, the disease abates and grasses begin to take off. However, in the very wet fall of 2018, TARR returned in October. Once again, lawns developed the insipid washes of yellowing blades. It wasn’t gray leaf spot, and it wasn’t brown patch, either – TARR was back.

My text to Colbaugh asked if it could really be possible that this ghost from the spring was reappearing in fall, and he assured me it was. And he said not only would it be a problem in the wet conditions of fall, but it was going to set us up for a rough round of TARR come spring. And so here we are in the spring.

I guess it’s time to get busy. Say it together, class. If you say it enough times, it will roll off your tongue as smoothly as “Imidacloprid” and “Bacillus thuringiensis.” You can do it! “Azoxystrobin!” Good. Now say it 25 times more.

You can hear Neil Sperry on KLIF 570AM on Saturday afternoons 1-3 pm and on WBAP 820AM Sunday mornings 8-10 am. Join him at www.neilsperry.com and follow him on Facebook.

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