UpDate - Vol. 12, No. 17, Page 13
January 21, 1993
Tiny flags help mushroom quality, improve production

     Mushroom companies in Delaware, Connecticut, New York, Pennsylvania,
California and Calgary, Canada are now using an inexpensive indicator
system developed at the University's Agricultural Experiment Station to
identify and correct costly airflow problems inside mushroom houses. The
system uses small plastic flags calibrated to test low-speed air movement.
     The flags have had a big economic impact on production. One grower
said that using them made the difference between losing and making money on
his crop. That's because proper ventilation is the key to quality in this
business.
     Like human skin, the surface of a mushroom must breathe to stay
healthy. If airflow over a bed of developing mushrooms is too great, the
caps dry out. Without enough airflow, they remain damp and are subject to a
disease called bacterial blotch that can render the crop unmarketable.
     In the late 1970's, mushroom growers in the Hockessin and Avondale,
Pa., first asked Ken Lomax for help. At the time, their main concern was
reducing energy costs. An associate professor in the Department of
Agricultural Engineering, Lomax soon realized that increasing energy
efficiency was only part of the problem.
     Producers also needed a low-cost way to test air movement through
their houses. Since air is invisible, ventilation adjustments were largely
a matter of guesswork. Growers wouldn't know they had airflow problems
until blotch showed up in the next crop of mushrooms. By then, it was too
late to salvage the crop. What was needed was an inexpensive way to monitor
airflow.
     Lomax said he got the idea for the flags after watching an airport
windsock, which is used to indicate wind direction for pilots.
     He and research associate Steve Gottfried started experimenting with
small-scale indicators that could serve a similar purpose inside a mushroom
house.
     Small plastic flags pinned to 12-inch long wooden dowels worked best.
After sampling many products, they discovered that a strip of 0.23 mil
flexible plastic film 6 inches long and 3/4 inches wide was ideal.
     It takes two people about 20 minutes to mark the position of up to 200
flags on a recording sheet. After adjusting the ventilation, another set of
readings is taken to determine the effects of that change. Once growers
become familiar with airflow patterns within a particular house, it takes
less time to make adjustments.
     After conditions are set, the flags are removed, sterilized and used
somewhere else. They won't be needed again in the same mushroom house
unless a fan is changed.
     Besides improving profits, the indicator system has proved to be a
valuable educational tool.
     "With the flags, growers can actually see what's happening to the
airflow," Lomax said.
     "Although the flag is beautifully simple, using it requires an
understanding of what it's telling you-the spatial geometry," he cautioned.
"You must visualize in 3-D what's happening in the air to make an impact.
     There's no single solution, but the indicators allow you to tailor
your response to the house and very quickly evaluate the effects of the
changes."
                                        -Doris Crowley