Farm Bureau Says Peach Growers Are in for a VERY Long Weekend

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COLUMBIA, SC – Freeze and frost warnings mean peach growers and other farmers will work around the clock, especially in the evening and nighttime hours, until threats of freezing temperatures are gone. Peach growers along the Ridge (parts of Saluda, Edgefield, Aiken, and Lexington Counties where a number of peaches are grown) and growers in the Upstate of South Carolina are bracing for possible freezing temperatures as early as tonight. Frost and or freeze damage can cause severe crop losses for peach growers who have already thinned their trees to hold just the number of peaches they will harvest this summer. Any loss now will eat into any profit growers might make.

Strawberry and other small fruit farmers will use large plastic covers for their fields or they will run overhead sprinkler systems at night to protect their crops. The most severe damage usually occurs when a freeze or frost takes place after buds and blossoms have begun to open, which is the case with most peach varieties in South Carolina.

SC Farm Bureau president and Sumter County farmer David Winkles said, “All farmers can do right now is put some degree of preventive measures in place, wait, hope, and pray for the weather not to be as severe as predicted. We’ve had an unusual spring with many varieties of plants blooming earlier than usual. That could lead to one of the best peach harvests South Carolina has seen in recent years. If we get a sustained hard freeze it could be one of the worst harvests for our growers because of the thinning they have already done on many of their orchards.”

A severe freeze can damage fruit which is already set, damage foliage, and can even kill limbs or entire plants. The degree of injury inflicted by low temperatures depends on a number of factors, including:

• the type of plant and variety.
• the stage of development of the crop. Most crops will be severely damaged once buds and blossoms begin to open.
• the amount of leaf cover over the blossoms and fruit. Leaf cover can provide some protection particularly against frost damage.
• the severity and duration of the freeze. The cooler the temperature and the longer the freeze period, the more severe the damage will be.
• wind speed. A four mile per hour wind will prevent frost from forming as long as the temperature remains above 32°F.

Various means have been used by peach producers to minimize the effects of freezing temperatures. Some of the more common methods are orchard heaters, wind machines, and overhead sprinkler irrigation.

Orchard Heaters:

Orchard heaters have been used for centuries to protect orchards. Most heaters are designed to burn fuel and can be placed as freestanding units or supplied by a pipeline network throughout the orchard. Propane, liquid petroleum and natural gas have also been used as fuels. The initial cost is generally lower than for other systems, but the cost of the fuel makes this system the most expensive in terms of operating cost.

Wind Machines:

Wind machines can be effective during a radiation frost. Their purpose is to circulate warmer air down to orchard level. A single wind machine can protect up to 10 acres. A typical wind machine is a large fan about 16 feet in diameter mounted on a 30 foot steel tower. The fan is typically powered by an industrial engine delivering 85 to 100 horsepower. Helicopters have been used as wind machines. They hover in one spot until the temperature increases, then they move to the next area. Repeated visits to the same area are usually necessary during a typical frost.

Sprinkler Irrigation:

Overhead irrigation is probably the most commonly used means of frost/freeze protection in the southeastern United States. Heat lost from the plant part to its environment is replaced by heat released as the applied water changes to ice. As long as water is supplied at an adequate rate the temperature of the plant will remain at or near 32° F. Advantages of overhead irrigation include lower operating cost, convenient to operate and multiple uses including drought prevention, heat suppression, fertilizer application and possible limb breakage from heavy ice loads.

Under-tree sprinkler systems have also been used successfully for freeze protection especially in citrus groves in Florida. This system utilizes the sensible heat of the water to raise air and foliage temperatures. This system does not provide the same degree of protection as overhead irrigation because les heat is liberated than by the latent heat of fusion released when ice is formed on the tree surfaces. A major advantage of the under-tree system is that limbs are not broken under heavy ice loadings. This can be a serious problem when using overhead irrigation on mature trees during an extended freeze.

Overhead sprinkler irrigation has proven to be one of the most effective means of protecting a variety of crops against frost/freeze damage. A properly designed system can protect crops to temperatures as low as 20° F.

Source – South Carolina Farm Bureau – where we are All About Agriculture and the Southern Region Small Fruit Consortium.