Thursday, May 26, 2011

Frost protection

Fruit blossoms can't take much frost.  Apple blossoms can take a couple of hours of temperature between 30-32.  Some will freeze, but some will just get frostbitten -- and perhaps the apple will have an odd deformity because of it.  Strawberry blossoms are similarly tender, but if they get bitten, you get nothing.

To protect the strawberries from frost, Farmer Bill runs sprinklers over the fields from the time the temperature hits about 33 until it comes back up above 33.  Anywhere from 3 to 10 hours.  I don't know the exact science, but essentially it's this: water creates heat as it freezes, so if you keep adding water to the plants, they stay heated enough not to freeze.  Or maybe it's this: the constant movement of the water doesn't allow it to freeze, so the blossoms can't freeze.  Whatever the reason, it works.  But having to run the sprinklers means a sleepless night, and getting sprayed with cold water in freezing temperatures.

In the day(s) leading up the a frost during blossom time, Farmer Bill sets up his irrigation system.  It's pretty ingenious, if labor intensive.  A large hose goes into the Straight River.  A pump is attached to the hose on the river bank, and the pump is powered by a tractor.  A series of 6-inch pipes leads from the pump across the farm -- originally this pipe was all underground.  In the middle of the farm, between the strawberry fields, risers are attached to the underground pipe, and smaller 3-inch, 30-foot long pipe goes from the risers across the aisles of the strawberries.  At the end of each 30-foot pipe is a sprinkler head.  It's a big job to get all of the pipes laid end-to-end and all of the sprinkler nozzles cleaned of debris.  Occasionally, the pipes burst apart.  Sometimes the nozzles insist on plugging over and over.  In the summer setting up the irrigation is not an unpleasant job because the river water is cool on a warm day.  In the spring it's a cold and wet job.

We have some tools that only come out during frost season.  A warning light -- that can be seen 1/4-mile or more away -- gets perched on a couple of milk crates in a low spot of a field.  This year, since we don't have to worry about the river field anymore, it will be easy to place the light where we can see it.  [In previous years, it was quite a trick to find a spot where we could see the light from the house, and it would still be in one of the lowest areas to give us the earliest possible warning.]  This light has been a wonderful thing.  It works very well, changing color from green (above 34), to white (34-32), to red (32-30), to flashing red (below 30).  Because it can be seen from the house, it means Farmer Bill doesn't have to get dressed and go outside to see a thermometer.  And it was much less expensive than a remote thermometer system that could read from the river field up to the house.  We just take the battery out and store it from spring to spring.  Another spring tool is a huge battery-powered lantern.  It shines a very bright light a long ways.  The light lets Farmer Bill see whether sprinklers are running without having to traipse up and down all of the rows of sprinklers.  Since I helped him do that traipsing the first year or two, I know how wonderful that light is...

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