June heat stress hurts Texas agriculture

A June heat wave caused agricultural conditions to decline around much of the state after steady improvements over the previous month, according to Texas A&M AgriLife Extension Service experts.

May rains dramatically improved soil moisture conditions in many drought-stricken areas of Texas, but triple-digit temperatures and little to no rain in June were trending many areas back toward drought. Various crops around the state were showing stress from high temperatures and lack of soil moisture, and livestock gains likely experienced heat-related declines.

Heat wave takes toll on Texas crops

The heat wave was especially harsh in the southern half of the state, where some areas experienced record temperatures.

All plants and vegetation experience heat stress during extreme daytime and nighttime temperatures like Texas experienced over recent weeks. Heat and inadequate soil moisture can stress plants, damage their cell membranes and disrupt metabolic efficiency during processes like photosynthesis and respiration, said Lee Tarpley, Ph.D., AgriLife Research plant physiologist, Beaumont.

But the combination of high daytime and nighttime temperatures can also economically damage commodity crops, especially during sensitive growth periods like pollination and flowering. 

Tarpley said the heat wave was rough on late-planted rice along the Coastal Bend. Yield potentials were high following good spring rains, but the heat arrived at a sensitive development stage for some fields – pollination. High temperatures can also negatively impact the viability of pollen, which can influence how the ultimate crop sets and fills out.

Similar setbacks are occurring in cotton fields that were setting bolls during the heat wave. Stressed cotton plants were aborting bolls in an attempt to hang on as heat indexes near 120 degrees put plants in survival mode, said Josh McGinty, Ph.D., AgriLife Extension agronomist, Corpus Christi.

Cotton crops were having difficulty withstanding the heat over the previous three weeks without adequate moisture, he said. Boll losses were especially bad in dryland fields where soil moisture levels have continued to decline. But even irrigation has not been enough as nighttime lows rarely dropped below 80 degrees.  

McGinty said high nighttime temperatures were not allowing cotton plants to shed the heat, which was causing plants to increase respiration. Increased respiration takes resources away from developing bolls.

“Small bolls are the first that the plant will sacrifice when energy reserves are depleted, but if the trend continues, larger bolls will be shed,” he said. “That shedding is evident with small bolls littering the ground in cotton fields.”

Not all the news about the arid conditions was bad. Larry Stein, Ph.D., AgriLife Extension horticulturist, Uvalde, said cantaloupe and watermelon fields in the Winter Garden and Central Texas were producing high-quality, super-sweet fruit. Irrigated vines were thriving, and brix counts were rising under the dry, hot conditions. Brix is the measurement of sugar in fruit.

But overall, Stein said conditions are declining, even for irrigated crops. Heat is not the problem though, it’s the lack of moisture.

“Vegetation is starting to burn up,” he said. “If you can maintain sufficient moisture for plants then they can cool with transpiration from the leaves, but the problem I see with the heat is stress and the other problems like spider mites and aphids, and everything takes its toll.”

Heat impacting livestock production

The heat wave took a toll on more than just crops. Jason Cleere, Ph.D., AgriLife Extension beef cattle specialist, Bryan-College Station, said cattle performance in high temperatures typically declines. Higher nighttime temperatures make it a challenge to get their core body temperature down. Their grazing may also reduce as they try to avoid activity in the sun.  

Cleere said Texas heat shows the importance of choosing cattle adapted to more tropical conditions like breeds with Brahman influence.

Forage production for hay, silage and grazing was very good over the last month, Cleere said. Producers were having problems with delays due to rain and excess moisture prior to the heat wave, but the arid conditions were sapping soil moisture levels quickly.  

Cleere said it is critical that cattle have adequate shade and fresh water during hot conditions. A cow can drink 20-40 gallons of water per day, depending on the moisture in the grass they are consuming. Cattle should have enough shade to spread out and cool down.

“A small shade structure where they can all barely fit under might be worse than no shade if they’re piled up,” he said.

June among hottest, coolest for parts of the state

John Nielsen-Gammon, Ph.D., Texas state climatologist and Regents Professor in the Texas A&M Department of Atmospheric Sciences, Bryan-College Station, said the heat wave produced eight “all-time” temperature and heat index records, from Tahoka to Cotulla. June was one of the 10 hottest on record for South Texas.

Most of the state recorded multiple days over 100 degrees, including half the month of June along the Texas-Mexico border up to Midland, five days in triple-digits in Dallas/Fort Worth and Bryan-College Station and three days in Houston.

Conversely, it was cooler than normal in northern parts of the state and one of the coolest Junes on record in Dalhart, near the top of the Texas Panhandle.

“It’s not the hottest summer so far,” he said. “But it’s been quite a bit more humid from all the rain in April and May, and that is where people are really feeling the heat.”

Nielsen-Gammon said high humidity and temperatures contributed to heat indexes well beyond 100 degrees. The dew point, the temperature at which dew forms, was around 70-75 degrees in Central Texas, which translates into an “icky” heat.

But the heat wave has also included a dry spell for much of the state, Nielsen-Gammon said. The same high-pressure system that kept the weather hot kept thunderstorms away from most of the state. The heat has sapped topsoil moisture from previous rains quickly in some areas of the state.

This drying down puts many areas at risk of returning to drought conditions following the earlier rains that had significantly reduced the amount of severely dry conditions, Nielsen-Gammon said. Dry conditions also contribute to higher temperatures because there is no evaporative cooling in the air.

“If we don’t get a decent amount of rain in the next few weeks, we will see more vegetation turning brown and crops suffering,” he said. “The Panhandle and East Texas have gotten enough rain, but the areas that are marginally out of drought are definitely at risk of slipping back.”

AgriLife Extension district reporters compiled the following summaries:

CENTRAL

There was limited rainfall coupled with another week of 100-plus degree days with even higher heat indexes. Soil moisture levels were short. Dry and hot conditions were affecting all crops. Hot, dry wind depleted soil moisture quickly. Pastures were beginning to turn brown. Hay baling continued but slowed due to the lack of new growth. Rangeland and pasture ratings were poor to fair. The wheat harvest was winding down, and corn silage harvest was underway. Sorghum fields were colored. Cotton was mostly in bloom. Some dryland sesame fields were planted. Fiber hemp was holding on in the heat but needed rain to improve fiber yield. Fly and tick numbers started increasing. Livestock were in good condition.

ROLLING PLAINS

A few areas caught much-needed rains and relief from high temperatures. However, most areas reported extremely hot and dry conditions. Wheat harvest and cotton planting were completed. Cotton looked poor so far in areas that did not receive rain. Rain was needed to maintain or improve livestock grazing conditions and fill water tanks.

COASTAL BEND

Topsoil moisture continued to decline with hot, dry conditions. Corn was in the dry-down stage. The dry-down stage was sped up by the last three weeks of 90-plus degree days and dry weather. Sorghum harvest was underway, and some corn was being harvested. Rice was 75% headed out. Pecan trees began shedding nuts due to dry conditions. Most first cuttings of hay were complete. Rangeland and pasture conditions continued to decline. Improved pastures were drying up fast. Livestock markets were holding strong, and cattle were doing well, but rain was needed for grass growth. 

EAST

Above-average temperatures and lack of rainfall caused soil moisture levels to dry up quickly. Subsoil conditions were adequate, but topsoil conditions were short to adequate. Pasture and rangeland conditions were good overall. Hay production continued and above-average yields were reported. Rain will be needed for continued grass growth for hay and grazing. Livestock were in fair to good condition. Some areas were experiencing growing grasshopper numbers. Wild pig activity and damage continued.

SOUTH PLAINS

Farmers continued to benefit from showers that delivered trace amounts of rain up to 1.2 inches across the district. Heavier rainfall totals were reported in western parts of the district. Cotton was in good condition, and corn was progressing well. Most farmers had to do very little irrigating due to the rainfall. Cattle were in good condition and taking advantage of the improved grazing.

PANHANDLE

The week was extremely hot with field conditions drying out fast, and temperatures reaching at or above triple digits. Irrigation systems were running where water was available. Producers were busy trying finish up planting and replanting summer crops. Wheat harvest was underway with average to slightly above average yields in irrigated fields. All crops needed rain. Corn was coming along but slightly behind on maturity levels compared to average years. Cotton was struggling in some areas and wilting under the extremely hot conditions, but other areas reported the crop was in good condition. Most pastures and rangeland were in good condition after recent rains helped grasses. Livestock were also in good condition with supplemental feeding happening on a very small scale. Producers finished bailing hay and wheat that replenished hay supplies.   

NORTH

Pasture and rangeland conditions were fair to excellent for most counties. Both subsoil and topsoil moisture were short to adequate. Light showers were reported by several counties. More rain would help crops through the extremely high temperatures. Wheat, corn, grain sorghum and soybeans all looked good. Bermuda grass was cut and baled. Insect pressure was increasing. Nuisance flies were heavy in the livestock area and house flies were thriving. Pockets of grasshoppers were in the pastures. Livestock conditions were good and continuing to improve.

FAR WEST

Temperatures were in the triple digits before dropping into the upper 90s with a few isolated showers that delivered trace amounts of rain. Cooler temperatures toward the end of the week eased the stress in cotton that had been suffering since it emerged. Irrigation was not keeping up with demand, and subsoil moisture was very short. Despite cooler temperatures, hot, dry winds continued to blow, which damaged crops and prevented herbicide applications. The earliest planted cotton was blooming. Some grain sorghum fields were beginning to head out, and melons should be ready for harvest soon. The first picking will most likely be light this season. Early planted corn looked decent as it pollinated before the extreme heat. However, later-planted corn showed poor kernel set and most all fields were burning up due to lack of moisture and not enough irrigation to keep up with demand. Pastures and rangelands were drying up rapidly and there was very little grazing available. Ranchers shipped all lambs off, and some goats were left to market. Ranchers continued to supplement livestock diets.

WEST CENTRAL

Conditions were extremely hot and humid with high temperatures over 100 degrees. Isolated locations received trace amounts of rain up to nearly 1 inch, but soil moisture levels were declining in most areas. The heat was taking a toll on crops and pastures. Grasses were turning brown. Fields that were not plowed were too hard to work. Hay harvests continued, and producers were cutting Sudan grass. Pasture and rangeland conditions were declining rapidly and showing signs of heat stress. Livestock body conditions were holding, and a few producers were putting out hay bales. Stock tanks were running low on water. Cattle prices were steady to higher, and demand for stockers was high. Producers finished planting and replanting cotton. Cotton progress ranged from squaring to emerging. Irrigated cotton and early planted dryland fields were in good condition but will need rainfall soon. Some young cotton was struggling along with corn and sorghum. Wheat harvest was complete. Pest pressure was increasing. The pecan crop outlook was poor to good depending on the variety.

SOUTHWEST

A heat wave continued to put high stress on agricultural production. Hot, humid conditions persisted, but rain ranging from 0.5-6.5 inches was reported over the weekend. Several locations reported 1-2 inches of rainfall. The rainfall will benefit later-planted corn and grain sorghum crops, cotton and pastures. Grain sorghum was coloring. Pecans were progressing. Grasshopper numbers remained high due to dry weather conditions; however, no significant damage was reported. Cotton was squaring but needed rain before plants begin to drop squares. Hay was being cut and baled, but rangeland and pasture conditions were declining in areas. Livestock markets were consistently high. Cooler temperatures were in the forecast.

SOUTH

Conditions were very hot. Topsoil and subsoil moisture levels continued to decline. Irrigated cotton continued to develop and started to set bolls. Peanut planting was completed, and fruit and vegetable production was slowing. Early planted peanuts were pegging. Corn fields were in the denting stage or drying down. Grain sorghum, sunflower and corn harvests were underway in some areas, and yields looked good. Dryland and irrigated cotton were showing heat stress, and plants were showing wilted leaves and shedding bolls and squares. Whiteflies were reported in cotton. Citrus and sugarcane were being irrigated. Sesame fields looked good. Hay grazer and Bermuda grass fields were being cut and baled, and producers continued to provide supplemental feed. Livestock conditions remained good, but pastures were burning up. Hay supplies were improving from recent production. Livestock and wildlife were in good condition, but body conditions were in decline due to heat stress. Quail pairs had not produced hatchlings. Rangeland conditions were declining. Beef cattle markets reported higher sale volumes as producers culled deeper. Producers were supplying water for livestock and wildlife.