WISCONSIN FRESH FRUIT AND VEGETABLE NEWSLETTER
September 15, 2007

Contents
Avoiding Frost Injury
Fall Chores on the Farm
Pesticide Storage
Degree Day Map
UW Contacts

Avoiding Frost Injury

             Much of Wisconsin is under a frost or freeze warning from Friday Sept 14 to Saturday Sept. 15.  Northern and western areas of the state are predicted to become colder than eastern areas and close to Lake Michigan.  This frost event is a radiation frost brought on by a large mass of cold air settling over the area.

            Frosts are typically of two types: Radiation frosts and Advective frosts.  Radiation frosts are associated with clear skies and calm winds and occur with high barometric pressure.  During radiation frosts heat radiates from the earth and vegetation into the atmosphere and the temperature drops as heat radiates outward.  If the frost event is not too severe it is possible to protect against radiative frosts through tarping plantings and through sprinkle irrigation.  Advective frosts are windy and are usually associated with a front of cold air moving in an area.  Skies may be clear or cloudy.  In this case warmer air at the ground level is replaced by cold air moving in behind a front.  Protecting against convective frosts is more difficult if not impossible.

            The importance of protecting against frost depends on the time of year and the crop(s) being grown.  For example, apples will tolerate a frost that dips to 28°F for a short period of time when the fruit are near maturity.  Tomatoes and peppers won’t tolerate temperatures below 32°F for even a few minutes.  Cole crops such as broccoli and cabbage can tolerate some light frost without injury.  Vine crops such as pumpkins can tolerate some light frost that will wilt the foliage, but the fruit will survive.

            The risk of frost varies significantly by location.  Sites with some elevation and with lots of room for cold air to drain away can stay several degrees warmer than adjacent low areas during radiation frosts.  Selecting a good site is the first key to preventing frost injury.

            For small plantings of vegetables or dwarf fruit trees covering the plants with tarps or row cover or blankets will help to retain heat in the canopy and will avoid frost injury.  Put the tarps out about sunset while the air is still warmish and remove them in the morning as soon as air temperatures rise above freezing.  Obviously, this is not practical for large plantings.

            Capturing heat that can be released during the night is another strategy.  If the soil is bare it will capture heat during the sunny days.  If the soil is dry and if there is no vegetation to block heat transfer the soil will lose substantial amounts of heat to the atmosphere overnight.  This may be sufficient to keep canopies above freezing.

            Berry growers, and to a lesser extent orchardists, can protect by sprinkler irrigation.  The principle of this technique is that as water transforms from a liquid to a solid it gives up substantial amounts of heat (latent heat of fusion).  This influx of heat through phase change can keep temperatures near freezing.  The amount of water required depends on the air temperature and wind speed.  Irrigation must continue through the night as long as air temperatures are below freezing so there is a constant layer of liquid water that can freeze, thus releasing heat.

            More information about frost protection is available at several University web sites.  I’ve listed a couple of good ones below.

 Teryl Roper, UW-Madison Extension Horticulturist

http://www.ces.ncsu.edu/depts/hort/hil/hil-705.html

http://tfpg.cas.psu.edu/40.htm

http://viticulture.hort.iastate.edu/info/06iawgmtg/frostprotectionhandout.pdf

Fall Chores on the Farm

             As we transition from summer into fall and then winter a number of items need to be taken care of before we get into seriously cold weather.  Below are some things that come immediately to my mind. 

1. Clean, drain, and winterize sprayers.  Each manufacturer may have their own instructions on how this is to be done, but in general the procedure is to drain out every last bit of water from the system and provide an appropriate antifreeze internal to the system in the winter.  The exact anti-freeze to use depends on your system.  Remove the nozzles and examine them for wear.  Order replacements for worn parts.  Store the nozzles in light oil.  Clean the exterior and touch up any bare or rusted spots with primer and paint. You may wish to put the sprayer up on blocks so the tires aren’t on the ground all winter.
2. Put all the equipment you can in inside or covered storage.  Leaving equipment out over the winter is hard on it and results in pre-mature wear and probably more maintenance work in the spring.
3. Berry Growers will want to get equipment and materials ready for mulching plantings that will carried over into 2008.  Clean straw is the best mulch.  Loosely spreading 3-4 inches of straw provides sufficient protection to dampen temperature changes during the winter and very early spring.
4. Mow the orchard short.  Mowing the orchard in the fall destroys habitat for rodents, makes their predators more efficient and thus prevents high populations from going into the winter in your orchard.  Once food becomes scarce, the bark of your apple trees will look very appetizing!  With high populations baiting in baiting stations with a zinc phosphide bait this fall with protect trees this winter.  Use bait stations for the bait to prevent off-target species from ingesting the bait.
5. Note areas with poor yield or poor quality and consider if these areas are profitable.  If not, remove the trees or berry plants.  Why keep blocks or fields that cost you money rather than make you money?  These blocks or fields reduce overall profits by draining resources that could be utilized more wisely elsewhere.
6. Examine your signs and sales room.  Are the signs attractive and readable?  Is there consistency throughout all your signs?  Do you have a logo that is used throughout your operation?  Has the paint on your signs faded or has the paint chipped and peeled?  Does your sales room look warm and inviting?  Is it bright with accents of colors or wood or is it cold and sterile?  When was it last painted or papered?  Fluorescent lighting fades colors.  Incandescent and halogen lighting makes colors rich, warm and inviting.  Install track lighting in the ceiling to point extra light on displays.
7. Are your production and financial records up to date?  Now would be a good time to record items that may have been missed during the rush of harvest.  Memory fades much faster than ink.
8. Assess the effect of your advertising program.  Did you advertise?  Did it help your sales?  How do you know?  What might be changed to improve for next year?  Do the people you want as customers come to your farm (i.e. those with $$$$)?
9. Did you have employee problems?  Now may be a good time to write down notes for policies you would like to institute next summer.  Consider assembling an employee handbook that outlines what jobs are and what is expected for each job.
10. Make your reservations for the 2008 North America Farmers Direct Marketing Conference.  Production workshops will be held on Monday February 18 at the Kalahari Resort in Wisconsin Dells.  If you have ever wished to attend this convention this is your year.  Since you won’t have to buy an airline ticket this is your year to make the conference ‘on the cheap’.

 Teryl Roper, UW-Madison Extension Horticulturist

PESTICIDE STORAGE

             It is time to make sure that any pesticides you are carrying over for subsequent years are stored properly.  Freezing can cause liquids and emulsifiable concentrates to separate making them difficult to use or ineffective in later uses.  Freezing is generally not a problem for powders, granules, pellets and dry flowable formulations.  Check the label if you have questions. 

            In general, pesticides should be kept in a cool, dry place out of reach of children, pets and wild animals.  Many growers store pesticides on high shelves or in a locked room or cabinet in an existing barn or machine shed.  While this is secure, it is probably not the best storage arrangement. 

            If you don’t have a dedicated pesticide storage facility consider constructing one.  For small farms a pesticide storage facility doesn’t have to be large or grandiose.  A small or medium sized “yard barn” such as those available at home centers would suffice.  It should be built on an impervious pad such as concrete with a berm around it to prevent liquid runoff.  You’ll want to insulate the building and have some source of heat to keep the temperature just above freezing during the winter.  You’ll also want to have ventilation to prevent fumes from building up inside of the building.

            Why not just store pesticides in a corner of an existing storage building?  If you should have the misfortune of a fire in that building the fire department that responds to your fire will likely stand back and watch the building burn.  If they put water on a pesticide storage facility the runoff could enter the soil.  If that happens you would have to pay to have the soil removed and remediated—an expensive proposition.  If a dedicated pesticide storage building catches fire you have only lost its contents and not expensive equipment.

            Don’t store pesticides inside your house or garage.  Fumes can escape into your home air creating at least a foul odor if not a dangerous situation.

            If you have pesticides that are no longer registered or that you no longer have use for contact your local county Extension office.  They can help you get the pesticides to a proper agricultural clean sweep where they can be disposed of properly.

            Make sure that pesticides are stored securely so that children or pets can access them.  Most pesticide poisonings are from children under 10 years of age.

            Proper pesticide storage may cost a few dollars and some time, but in the long run it will result in cost savings.

 Teryl Roper, UW-Madison Extension Horticulturist

More information about pesticide storage is available here:

http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-1096/F-7451web.pdf

http://pubs.caes.uga.edu/caespubs/pubcd/B1095.htm

http://pubs.cas.psu.edu/FreePubs/pdfs/uo213.pdf

Degree Day Graph

UW Fresh Fruit and Vegetable Contacts