2019 Texas Grazing Preview: South Texas and the Coastal Plain

Weeds are not always bad.  That’s the conversation lately in South Texas, concerning grazing and forage for cattle.

“Early spring weeds are very important especially in South and West Texas.  That bridges the end of winter feeding and the beginning of spring grass green up,” said Joe C. Paschal, Ph.D., Professor and Extension Livestock Specialist; Texas A&M AgriLife Extension in Corpus Christi, Texas who covers the area south of San Antonio known as the Rio Grande Plains and the Gulf Coast of Texas.

In addition to deer grazing on those winter weeds, Paschal said the weeds will produce seed for ground nesting birds like Bobwhite Quail, and cattle will ‘mop them up’ and enjoy foraging these weeds.  “There are good weeds and there are bad weeds.  People in ranching like to have their cattle on certain weeds that are called tallow weed with a high oil content.  Nobody would want to get rid of those…Particularly weeds in February to March…are high in protein,” added Paschal.

Percent of Average Precipitation Since October 1

Most of Texas has been wet for the 2019 Water Year that starts Oct. 1 2018 and runs to Sep 30, 2019.

Evaporative Demand Since January

Evaporative demand has been well below normal since January, which means much of the precipitation that has been received has been able to stay in the plants and soils.

Most weeds can be beneficial, but when they take over a pasture, control may be necessary.   Another range specialist in South Texas recommends controlling the noxious weeds.  “As a good rule of thumb, treating annual broadleaf weeds when they are about six inches tall or less yields higher control, whereas perennial weeds often can be more easily controlled when they are a bit bigger with more leaf coverage. It is important to seek professional advice if necessary to identify your problem weeds and ensure proper treatment,” cautioned Megan K. Clayton, Ph.D.,Associate Professor and Extension Range Specialist at Texas A&M AgriLife Extension Service/Department of Ecosystem Science and Management in Corpus Christi, Texas.

“If you are dealing with a mixture of weeds in a pasture, it may be necessary to either 1) pick what you are most mad at to treat first or 2) treat at different times during the season, making sure to not exceed the maximum application rate on herbicide labels,” Clayton advised.

Livestock producers who consistently graze cattle conservatively and leave about half of the desirable grass plants standing as forage instead of grazing to the ground, benefit from healthy soils, high rainfall infiltration into the soil, and grasses with healthy roots, Clayton pointed out.  “Setting yourself up with roots that can reach good subsoil moisture not only allows your plants to green up faster than the neighbors’, but also maintains growth for a longer period of time despite temporary dry periods,” she advised.

Much Too Early Map of Areas Greening Up Based on Satellite Imagery

The below map is from the MODIS Terra Satellite and the Normalized Difference Vegetation Index or NDVI.  The average value was taken between March 28 and April 26, 2019 compared to the entire data set from 2002 to present for March – April.  South Texas in particular is seeing plant growth well above what would be expected for this time of year.

While rainfall during the past couple of growing seasons in South Texas has been spotty, most of the area was fairly dry last spring/summer followed by a very wet fall/winter…and those dry/wet conditions can often lead to a huge weed crop as we  green-up, Clayton noted, with many reports of specific weed issues landowners do not remember dealing with in years past.

In deep South and West Texas, ranchers typically have less rain and more range with both native and introduced bunch grasses (and a fair share of invasive grass species as well.) 

“As you get closer to the coast, but still in South Texas, we see smaller pastures and more introduced and invasive grasses, mostly sod forming varieties. In both examples, these grasses are adapted to the rainfall patterns of both regions IF they are properly stocked and grazed,” observed Paschal.  “Typically ranchers in the south and west are better than those nearer the coast in doing this properly, so that when we do have irregular rains or intemperate temperatures, producers and their cows are less likely to be affected by significant (deteriorating weather) changes,” said Paschal.  

Recent drying trend in South Texas: Number of Days Since Significant Precipitation has been Observed

South Texas and parts of the Gulf Coast have seen a recent drying trend. Some areas have gone 25 days or more since seeing a quarter inch of rainfall. While this isn't cause for alarm, it is something to track as we enter summer.

Subsequently, Paschal found that these spring cows in the western and southern parts of Texas ‘wintered’ in better body condition even though they were fed less hay, while those in the eastern part required more hay and supplemental feed.

As Texas and several surrounding states have learned from this past El Niño winter and early spring, what compounding the problem was the dry spring in 2018 followed by the very wet summer and fall.  Ranchers throughout the coastal and extreme South Texas fed their first cutting of hay from 2018 to their cows in the summer and then it began to rain; preventing the second and third hay harvests, which led to a shortage of hay this winter. 

“Hay supplies were short and expensive, especially hay of any quality. The excessive rains (although not of hurricane levels) were persistent and kept hay equipment out of the fields and often caused problems in grazing. Grazing in the heavy clay soils along the coast caused compaction. Wet conditions increased internal (stomach worms and liver flukes) and external (horn, stable, and horse flies and mosquitoes) parasite burdens and in some cases increases in diseases such as the Blackleg, Redwater, and also Leptospirosis,” said Paschal.  Leptospirosis is a common bacterial infection of cattle, which can cause abortion, infertility, illness, and even death.

Because the cows (and bulls) were in poor body condition due to the prior drought and then the persistent rainfall, cow re-breeding rates were lower, as were calf weaning weights.  “It was a wreck all around for many along the Coast,” concluded Paschal.

Meanwhile, Paschal says this spring is showing much promise.   He said some of those early late winter/early spring weeds actually help replenish body condition on a cow or a fall born calf that wintered poorly.

Those that have been grazed and stocked properly have improved the most.....if there is a take home point to any article on the weather and grass production, that should be it.

Joe C. Paschal, Ph.D., Professor and Extension Livestock Specialist; Texas A&M AgriLife Extension in Corpus Christi, TX

“I agree that at some point they (some weeds) need to be treated, especially those that won’t ever be eaten!  Pastures and rangelands have shown great improvement this spring with the adequate rainfall, even with the erratic temperatures.  Those that have been grazed and stocked properly have improved the most,” said Paschal, adding, “If there is a take home point to any article on the weather and grass production, that should be it.”

Another management practice on ranchers’ minds this time of year is brush control.  “In about another month, we will be deep into mesquite and mixed brush herbicide treatments here in south Texas. “Whether you plan to individually treat trees with a leaf, stem, cut stump, or mechanical method or broadcast leaf herbicide, prior planning right now can set you up for success,” said Clayton.

Practically all brush in South Texas are resprouters, meaning they will sprout back from buds on the stem underneath the soil surface if top-killed or top-removed.  This makes for challenging management because simply cutting down the trees leads to a smaller, multi-stem tree that is harder to control later on, Clayton noted.  

Clayton recommends: identifying your target brush species, learning about your treatment options, and selecting the option that provides the best control the first time; while still realizing that some management funds will be needed for follow-up treatments next year.                                                        

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