Citrus Damage Shows Up After Freezes

From The Fresno Bee, January 4, 2010, by Elinor Teague:

Before the hard frosts in December, our six mature grapefruit and orange trees were loaded with ripe fruit. About one-fifth of that fruit has fallen from the trees during the last few weeks. The fallen fruit looks good, but the interior pulp is slightly discolored and seems to be dried out.

This is the result of freeze damage to citrus. Most of the fallen fruit was carried on outer branches where it was completely exposed to the cold.

The fruit on inner branches that was sheltered from the below-freezing temperatures does not seem to be adversely affected (very tasty, as a matter of fact). Our trees show no other signs of freeze damage, but the damage from the freezes may not show for several weeks or months, and the extent of severe damage may not become apparent for another year.

Light cold injury to citrus will show in two to four weeks as leaves and new shoots that look burned or dead. Limb die-back, a sign of moderate damage, will continue for several months through the spring.

Severe cold damage in which the scion [shoots or twigs] and the top limbs are killed may not be obvious until mid-summer.

Pruning out damaged branches and limbs must be postponed until the extent of injury is obvious. The goal of pruning citrus after freeze damage is to preserve as much of the trees' framework and foliage as possible and to prevent or control the growth of new suckers.

Citrus trees begin to regain their full vigor in late winter and early spring after the crop is harvested. The reinvigorated trees' first response to freeze damage is to produce new sucker growth.

Damaged leaves and twigs on the exterior canopy of lightly freeze-damaged citrus can be sheared, retaining as much foliage as possible to support the root system and the new crop.

Lightly damaged trees should produce few suckers. On trees that have suffered moderate damage, prune dead limbs back to a strong shoot or branch and remove excess suckers throughout the year (they're easy to snap off at the base when small).

Severely damaged trees may need professional help to be properly restructured.

Remove damaged fruit and fertilize lightly damaged trees as usual. To prevent excess sucker growth, feed moderately and severely damaged trees lightly or not at all this year.

Once again, PAR (Plant A Row for the Hungary) is collecting extra citrus to be distributed through the Salvation Army's or Community Food Bank's network of food pantries. You can deliver your extra citrus to PAR on Saturday and March 13th at the Garden of the Sun from 9 a.m. until noon.