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Summer's hottest days challenge crops, animals
MISSISSIPPI STATE -- From the catfish in the smallest pond to the tree with the deepest root system, Mississippi's agricultural commodities are feeling the heat.
Catfish, poultry, livestock, field crops and timber are struggling through the hottest days of summer, much like the farmers who grow them. The damage from heat stress can be seen in a matter of minutes in some of the most vulnerable animals, catfish and poultry; in days or weeks with field crops or livestock; or in months or years in the case of timber.
While extremely hot days are not unusual for this time of year, animal producers must provide as much relief as possible, monitor their animals closely and be prepared to respond quickly if necessary.
“A catfish farmer can keep his pond aerators working properly night after night, but it just takes one delay in reacting to an equipment breakdown to lose $60,000 worth of fish in minutes,” said James Steeby, aquaculture specialist with Mississippi State University's Extension Service.
As water temperatures increase each summer, farmers have to run aerators through the night to keep pond oxygen levels appropriate for fish.
“It's a double-edged sword. The water holds less oxygen when the temperatures increase, and fish need more oxygen at the same time,” Steeby said. “The people working at night have to be extremely reliable and on their game.”
Craig Coufal, Extension poultry specialist, said heat becomes an issue every summer. Birds typically eat less, and body weights are lower at processing time. Mortalities are not uncommon.
“Modern broiler facilities are environmentally controlled with evaporative cooling pads and fans to help keep the birds cooler,” Coufal said. “Shade and fans with misters blowing on truckloads of birds are available outside the processing plants to help, too.”
Poultry producers must monitor their birds closely during heat waves.
“You don't ask a chicken farmer to leave his farm in the summer. He's going to be near his birds throughout the hot weather,” Coufal said. “If something does break down, it is a matter of minutes before the impact is felt.”
Jane Parish, Extension beef specialist, said heat stress can reduce cattle appetite, growth and milk production. Hot weather can hurt reproductive performance and, in extreme situations, cause death.
“Cattle need access to clean water and proper mineral supplements at all times. They also should not have to travel long distances for water,” Parish said. “Cattle need plenty of shade from trees, sheds or portable shades, but limited shade can be worse than no shade at all if cattle crowd too closely together.”
Parish said producers should work cattle in the morning. However, feeding in the afternoon, instead of the morning, tends to help reduce heat stress.
Normie Buehring, research professor at the Northeast Mississippi Branch Experiment Station in Verona, said the lack of soil moisture is the biggest problem for most crops.
“If crops get water, they can tolerate the heat much better. When it's hot and dry, plants will reach the wilting point quickly. Many will not recover and will be unable to fill out pods and seeds. Cotton will shed bolls,” he said. “Much like people, plants have to respire to stay cool. In these conditions, plants are using their energy to cool off instead of filling out seed or bolls.”
Buehring said most of the corn in the area is finished, and the hot, dry conditions will help those plants dry down faster. Soybeans and cotton will share the brunt of the damage from the weather conditions.
“Growers with access to irrigation never want to get behind, especially this late in the year. With cotton, they should not stop watering until the first bolls crack open,” Buehring said. “We think of cotton as a hot-weather crop -- and it is the most heat-tolerant crop we grow -- but research suggests that 68-85 degrees is the ideal temperature for cotton.”
Some of the state's timber is already dying from several years of dry conditions. The drought stress has made many trees more susceptible to insects and diseases. Still more trees will show the effects of this summer's hot, dry conditions in the months and years to come.
“We are not just looking at one dry summer, but several dry summers,” said Andy Londo, Extension forestry specialist. “There is a cumulative effect that leaves trees progressively more stressed and more susceptible to insects and diseases each year.”
Londo said new pine plantations have been hit hard by conditions this summer.
“For some of these plantations, a week of 100-plus temperatures is the death nail. The trees were stressed already,” he said.
Heat-stress concerns are not limited to Mississippi's agricultural commodities. Ted Gordon, Extension risk management specialist, said there are more workers' compensation claims for heat illness in agricultural workers than any other occupation.
“Pesticide handlers who wear protective clothing should use extra caution and take cool-down breaks to protect against heat illness,” Gordon said. “That is important even when wearing normal clothing when temperatures are this high.”