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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY-SOUND PEST, WATER AND SOIL MANAGEMENT STRATEGIES FOR NORTHERN GREAT PLAINS CROPPING SYSTEMS Title: The ABCs of Front Management

Author
item Evans, Robert

Submitted to: Washington State Horticulture Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 16, 2009
Publication Date: N/A

Interpretive Summary: Cold temperature damage to crops in the USA and around the world result in major economic losses to the agriculture and landscaping industries. The USDA's Economic Research Service (2008) states that since 1988, about 10 percent of the total Federal Crop Insurance indemnities have been due to frost, freeze, and cold weather. This is about equal to nationwide damage payments due to hail; however, many crops are not insured. NOAA (2008) estimated that the January 2007 freezes in California resulted in losses over $1.4 billion to the citrus industry alone and there was one fatality associated with the event. Several other high value crops were also damaged and the total economic losses to California growers considerably higher. A series of freeze events in April 2007 affected at least eighteen southeastern states with estimated losses of over $2 billion to fruit and field crops as well as the ornamental plant industry. The protection of plants against cold temperature injury remains a crucial element in commercial crop production in the spring when budding plants are sensitive, and can also be a cultural requirement in the fall and winter months depending on the crop and cold severity in temperate climates Cold temperature protection events commonly occur during "radiation" frost conditions when the sky is clear, there is little wind and temperature inversions can develop. Good frost management is a combination of both passive and active measures. The best frost protection technique is always good site selection. Overtree sprinkling systems provide the greatest levels of protection but require large amounts of water. Total water requirements for overtree sprinkler systems can be reduced by targeting applications to only the canopy. Undertree sprinkling systems are usually a good option for frost protection in orchards. Wind machines or "fans" rely totally on the strength of the temperature inversion for their effectiveness in warming the orchard. Currently most supplemental heating for cold temperature modification to protect horticultural crops is provided by fossil fuels; however, these practices may be economically infeasible for many growers. While there is no perfect method for cold temperature protection, quite often combinations of methods are advantageous.

Technical Abstract: Frost protection or protecting plants from cold temperatures where they could be damaged must be a major consideration in orchard planning. Cold temperature protection events commonly occur during "radiation" frost conditions when the sky is clear, there is little wind and temperature inversions can develop. These conditions can happen during spring, fall or winter when it is necessary to keep trunks, buds, flowers, small fruit or foliage above their "critical" temperatures. Good frost management is a combination of both passive and active measures. The best frost protection technique is always good site selection. Overtree sprinkling systems provide the greatest levels of protection but require large amounts of water. Total water requirements for overtree sprinkler systems can be reduced by targeting applications to only the canopy. Undertree sprinkling systems are usually a good option for frost protection in orchards. Wind machines or "fans" rely totally on the strength of the temperature inversion for their effectiveness in warming the orchard, and may also be helpful in pushing cold air out of a vineyard. The placement of multiple wind machines must be carefully coordinated to maximize the areal extent and net effectiveness. Currently available fossil fuel-fired (oil and propane) heaters can be a big asset in frost protection activities, but are very inefficient and costly to operate. While there is no perfect method for cold temperature protection, quite often combinations of methods are advantageous. Wind machines have been found to work well with undertree sprinklers or with properly placed fossil fuel heaters. A well-maintained and calibrated frost monitoring (thermometers and alarms) network will always be required. Knowledge of the current critical temperatures and the latest weather forecast for air and dew point temperatures are important because they tell the producer if heating may be at any stage of plant and bud development and how much of a temperature increase should be required to protect the crop.

Last Modified: 10/20/2014
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