Thermometer Gun Measures Crop Stress

Thermometer Gun Measures Crop Stress CROPS Miscellaneous 4-3-16 A normal crop with plenty of water is usually as much as 11 ? cooler than the air, say plant scientists. However, when adequate moisture is not available, or if plants are attacked by insects or disease, plant temperature may be from 3 to 11? above surrounding air temperature. Now, a newly developed infrared "gun" can shoot the temperature of plants and air simultaneously. "Generally, if crop temperature is less than air temperature, plants are not under stress," says Dr. Robert Reginato, researcher at the Water Conservation Laboratory, Phoenix, Ariz., who helped develop specifications for the gun and also helped field test it. Says Reginato: "We can pretty well tell if a crop is under stress by measuring temperature of plants vs. air temperature at about 1:30 to 2 p.m. But we can't tell by reading the gun whether the stress is due to lack of moisture, insects or disease. That requires closer examination of the plant." The 2 lb. Telatemp infrared thermometer gun has been tested and evaluated in the field and was used to develop a "stress degree day" concept similar to the "growing degree day" concept often used in classifying seed corn. According to tests in California and Arizona, each day the crop temperature exceeds air temperature by 1 degree C results in one "stress degree day" to the crop. After 15 stress degree days the crop has extracted most of the available water from the plant root zone and irrigation should begin promptly. Thus, the gun can be used to precisely schedule irrigation without overwatering, or going too long between irrigations and causing undue crop stress. Extended stress accumulation can lower crop yields. R. E. Darringer, of Telatemp Corp., says the first guns will be hand held models and most of them will be used by researchers, crop consultants or groups of farmers who invest in a gun collectively and check all their fields on a regular basis. However, by irrigating only when necessary, scientists say it may be possible to save from 4 to 6 in. of water per crop and the gun could pay for itself in one season. Retail price is right at $3,750. Future temperature guns, says Reginato, may be mounted in airplanes or even satellites and used to monitor large areas. Possibly, through computerized automatic controls, they might even start irrigation equipment and precisely control the amount of water applied to a given field. For more information, contact: FARM SHOW Followup, E. R. Darringer, Telatemp, Corp., Box 5160, Fullerton, Calif. 92635 (ph 714 879 2901).

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