Fruit frost damage

PREVENTIVE. If possible, remove fruited canes in the same year (Caution this increases the risk of frost damage). 

Like other fruit trees, peach trees need a period of cold weather rest or dormancy. The number of hours of cold between 32° and 45°F each cultivar needs before it breaks dormancy is referred to as chill hours. (Cold below 32°F doesn t count toward meeting the dormancy requirement.) Once the number is reached, the tree assumes winter is over and starts growing the next warm day. Peaches bloom rapidly once their requirement has been met, which makes them more prone to frost damage than other fruit trees that are slower to burst into bloom. Call your local extension service to find out how many chill hours your area receives and what cultivars match that requirement. If you choose a cultivar that needs fewer chill hours than you normally receive, an unseasonable winter thaw in your area may bring the tree well into flower weeks before spring actually arrives. But if you choose one that needs more chill hours than your climate supplies, the tree won t get enough ehilling to stimulate normal bloom, v... 

Symptoms Rowers affected by frost have black centers, unlike the yellow centers of undamaged flowers. The tips of damaged fruit may be deformed. For stem symptoms, see Frost Damage on the opposite page. 

Symptoms In the dead of winter, a combination of heat and cold can cause sunken areas or long cracks to form in the bark of woody plants. Damage is most common on the southwest side of a trunk. The last light of day warms the bark, then the bark rapidly cools as the sun drops below the horizon. For symptoms on fruit, see Frost Damage on the opposite page. 

Some farmers make use of the heat of fusion of water to protect fruit from freezing. They flood their orchards or fields with water, as shown in Figure 16-11. The energy released as the water freezes often increases the temperature of the air enough to prevent frost damage to the fruit. 

Soybean oil was used as an antifoam agent in aerated fermentations such as productions of penicillin, streptomycin, and tetracycline. It also markedly increases the yield of antibiotics, presumably by providing important nutrients (Smith Thompson, 1989). Soybean oil also was observed to delay the onset of blooms on fruit trees, reducing susceptibility to frost damage. 

Symptoms Overnight, flowers and buds become discolored, usually brown. Frosted blooms may not produce fruit. Leaves and stems turn brown or black young growth toward the outside of the plant will be most affected. Apple skins may be russeted, usually at the flowering end of the fruit opposite the stalk. Damage may not be noticed until the fruit has developed. 

The addition of heat to ahody of water, a condition known as thermal pollution, represents virtually no problem for humans. In fact, thermal pollution can even have certain advantages. For example, water heated by such processes can he used to spray on fruit trees to prevent damage from frost. It can also he used, under controlled circumstances, in aquaculture, the controlled cultivation of fish and seafood. 

A layer of straw is placed beneath the strawberry plants to make sure that the fruits stay clean and to prevent the spread of grey rot and rhizome rot [Phytophthora cactorum). In addition the straw conserves soil moisture (this can also be a disadvantage), suppresses weeds and makes it easier to move around. The straw (80-100 kg/acre) is put down just before the fruits touch the soil. If this job is carried out before or during flowering, there is an increased risk of damage from late frost (because the soil is... 

Flowers damaged by frost will produce deformed, cat-faced fruit. If spring frost threatens, cover beds overnight with a blanket. 

Select only the best fruits for storing any fruit that is bruised, has broken skin or shows signs of pest or disease damage should not be stored. The storeroom must be frost-free, safe from pests, rainproof, and ideally at a constant temperature with air circulating freely so that the atmosphere doesn t get too dry or hot and humid. Different crops have different temperature and humidity requirements, but a suitable average temperature is 40-50°F/4-7°C. 

Rotary sprinklers. Each rotating sprinkler covers an area about 21-36 m in diameter. The sprinklers are usttally spaced 10.5 m apart along the supply line which is moved about 18 m for each setting. Special nozzles can be used to apply a fine spray at 2.5 mm per hotrr for frost protection of fruit crops and potatoes. Icicles form on the plants, bnt the latent heat of freezing protects the plant tissne from damage. 

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