None like it hot   Resize text          This summer is shaping
up to be one of the most stressful to Missouri crops in recent
years. The combination of low precipitation and high atmospheric
demand for water makes 2012 feel much like 1988. One of the
driving forces for increased atmospheric demand is air
temperatures much higher than normal. These high temperatures
often have direct effects plants on plants, as well as
aggravating water stress.  It is important to remember that
plants react to temperature differently than humans. Humans must
evaporate water to dissipate heat. High humidity reduces
evaporation and greatly affects the way a particular temperature
feels. Thus, weather stations report heat indices that are an
attempt to estimate how air temperature “feels” to humans. High
humidity translates into heat indices that are often five or
more degrees above air temperature. Heat indices have little
relationship to the direct effects of temperature on plants.
Sometimes leaf temperature is more important