For The Answer
Express-News Weekly Column
Saturday, October 25, 2003
Submitted by Calvin Finch, Ph.D., Conservation Director, San Antonio Water System, and Horticulturist
Lawns are always an important topic in South Texas. It is not easy to have a “perfect” lawn and the effort can be expensive and waste water. There are also several plant diseases that are prevalent right now because of the mild damp autumn we are having.
If you have just purchased a newly constructed home, here is some guidance in dealing with the bare ground this fall. You can apply sod at any time. Sod is especially important to prevent soil erosion and reduce mud tracked into the house. If the sod is dormant (not green) make sure you purchase it from a reliable supplier. Dormant sod and dead sod (due to drying and freezing) look the same but, of course, do not perform the same. Dormant sod will green up next spring.
If you are going to have a lawn make sure your builder provides at least 4 inches of soil over the entire lawn area. If some of the soil is compost that is even better. If you apply compost, buy it already incorporated in the soil as a landscape mix or till it in. Layers of compost over hard soil do not work well.
Sod on rock or on less than 4 inches of soil will be a constant problem. Even if you must pay for the extra soil, make the investment; it will be paid by in just one or two dry summers by water cost savings. If you are a SAWS customer and have the 4 inches of soil, select zoysia, buffalo or Bermuda grass, and your lawn covers less than 50% of your yard, you may receive a rebate to help cover any costs. Visit www.saws.org or call 704-7527 for more information.
There is another option if want to wait until next spring to apply sod. Spread rye grass seed over the bare soil where the new lawn is going to go and apply mulch over the areas where you are going to eventually plant groundcovers, perennials, and shrubs. The rye grass will sprout quickly to protect the soil. It makes an attractive lawn until hot weather kills it in May, the ideal time to plant Bermuda grass seed or apply sod. The mulch will also protect the soil, eliminate mud, and reduce weeds until you can plant. Plant your landscape plants right into the soil under the mulch. The mulch will be beneficial to the new landscape plants.
If you have round faded looking spots in the grass, especially St. Augustine, that seem to be expanding, it is probably brown patch. Brown patch is a fungus disease that works at the base of the blades during the autumn and spring. The disease does not kill the entire grass plant so sometimes the middle of the infected area can be putting out new green blades while the infection edge is still spreading. If that situation exists, the infection areas may look like donuts. Other times, however, the killed areas are less distinct. If killed areas are actively growing in your lawn now, it is probably brown patch.
Stop the brown patch infection from spreading by applying a labeled fungicide. Bayleton or Turfcide (Terraclor) work well. The fungicide will stop the infection spread but healing may not occur until next spring. It is never a good idea to mow a lawn when it is wet but, if your lawn has a fungal infection, it will certainly spread the disease. Even foot traffic by pets or people will start new infection centers. For long-term treatment of brown patch do not water the lawn as soon as the days shorten and nights become cooler (September). Aeration and top dressing with compost reduces the chance of infection, especially if you slightly raise the elevation of the low spots where brown patch usually starts in a lawn. Compacted low areas in over watered lawns are most likely to be infected by brown patch every year. Top dress and aerate in February.
The symptoms of Take-All Patch resemble brown patch with several important differences. The dead areas of this fungus disease usually appear in the summer, and the areas are truly dead, roots and all. Fungicides do not control Take-All Patch. The best treatment seems to be to apply about .5 inches of an acidic compost over the dead area and into the live lawn surrounding it (2 feet). Apply the compost now. The best products also appear to be the least expensive, about $3 per bag. Look for “Compost Peat”, “Michigan Peat”, or any compost material with origins of Northern peat bogs or East Texas acidic materials. Another product, HuMor, has been effective in some tests.
The Take-All Patch will be even slower to heal than brown patch so do not be impatient. Growing a perfect lawn in South Texas is not an easy task.