Problem Identifier Unit Screen//v.w/ RR Template

Problem Identifier Unit Screen//v.w/ RR Template Cold Damage

Problem
The tree has been exposed to freezing temperatures. Tender shoots may blacken and die; older foliage often turns yellowish brown, leathery, and eventually withers and falls. The fruit rind may be scarred with brown or green sunken lesions. Or, even though the fruit rind appears normal, when the fruit is cut open, the flesh is dry. Severely damaged trees suffer twig and branch dieback. The bark along the branches or trunk may split open.

Analysis
Citrus plants are frost tender, and are easily damaged by temperatures below 32°F. Although many citrus plants can recover from a light frost, they cannot tolerate long periods of freezing weather. Damage to fruit occurs when the juice-filled cells freeze and rupture. The released fluid evaporates through the rind, leaving the flesh dry and pulpy. In addition to causing leaf and twig dieback, temperatures of 20°F and lower promote bark splitting, which may not become apparent for several weeks or months.

Solution
Don't prune back damaged branches immediately. If there is still danger of frost, drive 4 stakes into the ground around the tree, and cover the tree with fabric, cardboard, or plastic. If possible, place a lamp under the cover. Turn the light on during cold nights. Remove this cover when the weather warms up. The trunks and main limbs of young trees may be protected by wrapping them with corn stalks, palm fronds, or fiberglass building insulation. Do not shade the foliage. Keep the soil moist during a freeze, but be careful not to overwater. Limit fertilizer to a minimum. Damaged fruit can be removed immediately following the freeze. Always wait for new growth to appear before pruning. As soon as the danger of frost is past, you can prune blackened shoots and withered foliage. If the tree has suffered serious injury, it may take as long as 6 months before you will be able to determine the extent of the damage to the trunk and main limbs. You can then prune out the dead wood. (For more information on pruning, see ORTHO's book All About Pruning.)

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