Protect peach trees frost

How to Protect Fruit Trees from Frost

How can I prevent a late spring frost from damaging our fruit crop?

You can take several fairly simple steps to reduce the risk of frost damage to buds, blossoms and fruit without using heaters, commercial wind machines or overhead sprinklers, according to the University of California, Davis’ article Principles of Frost Protection. First, before planting fruit trees of any kind, choose the location carefully. Avoid planting at the bottom of a slope — where frost accumulates — or on cold hilltops. If possible, plant on a north-facing slope to help delay blooming and thus avoid frost damage. The Alabama Cooperative Extension System (ACES) suggests checking seed catalog descriptions and choosing fruit varieties less susceptible to frost damage in order to find varieties that bud and bloom later, when frost is less likely to occur.

For existing fruit trees, ACES recommends putting off pruning until late winter to early spring to stall budding and blooming. If frost is in the forecast when trees are in bloom and the soil has been dry, water the soil a day or two beforehand to a depth of 1 foot (wet soils radiate more heat than dry soils do). To trap extra warmth, the UC Davis article says to cover the wet soil around the bases of the trees with clear plastic until the danger of frost has passed. If you’re using a cover crop, mow it and remove vegetative mulch (at least temporarily). Bare soil — or soil covered with clear plastic — stores and radiates more warmth.

ACES also notes that frost blankets can provide frost protection for fruit trees and small fruits. When you place frost blankets around tree trunks, be sure to anchor them on the ground to trap the soil’s radiant heat.

— Vicki Mattern, Contributing Editor

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Vicki Mattern is a contributing editor for MOTHER EARTH NEWS magazine, book editor and freelance magazine writer. She has edited or co-authored seven books on gardening, and lives and works from her home in northwestern Montana. You can find Vicki on Google+.

Protect Your Trees From Freeze

Temperatures below 32 degrees over a sustained period of time are cold enough to freeze your trees’ buds/blossoms, fruit, leaves, and/or twigs.

Trees most susceptible to damage:

Citrus, Jacaranda, Catalpa, Oleander, Eugenia, and other tropical/sub-tropical plants are most likely to sustain damage. Tender, new growth is also easily injured by freezing temperatures.

Acute action before freezing weather:

Protect your trees and plants:

  • Cover susceptible trees and plants with burlap, sheets, tarps, etc., that extend to the ground to trap in the earth’s accumulated warmth. Use a frame or stakes to minimize contact between the cover and the foliage.
  • Bring potted plants and trees to more protected locations.

Keep plants well-watered:

  • Moist soil will absorb more solar radiation than dry soil, and will re-radiate heat during the night.
  • If you have a large tree that needs protection, running sprinklers at the coldest time of the day (usually between 4:00AM and 6:00AM) can give it a slight edge. The strategy makes use of latent heat released when water changes from liquid to a solid. When ice crystals form on the leaf surface they draw moisture from the leaf tissue. The damage from this dehydration will be less severe if the plant is not already drought-stressed.

Advanced planning for freeze

  • Remove turf/weeds from under trees’ canopies—bare soil absorbs and reflects heat best.
  • Wood chip mulch prevents soil moisture loss and insulates roots.
  • Plant frost-sensitive plants near sources of reflective heat (like buildings, walls, etc).

Action after a freeze

Help trees recover:

  • Do not prune anything off immediately. Wait to see what sprouts in the spring; the damage is often not nearly as bad as it initially looks, and new growth may come out of tissue that you thought was dead.
  • If dieback is severe enough and your tree has lost “shade,” protect the now-unshaded portions of the trunk/branches from the sun, with a physical cover or with whitewash (1:1 ratio of latex paint and water).
  • Remove frosted/mushy fruit while still salvageable, for snacking on or juicing.

Fruit mummies can harbor spores, fungus, and diseases which can ruin crops. (Photo credit: Jack Kelly Clark) A successful summer harvest of peaches and nectarines starts in winter. General clean up, pruning, and dormant spraying will help prevent disease and keep your trees in good health.

Remove and destroy all mummified fruit hanging on tree branches or littering the ground. Although they look harmless mummies can harbor spores, fungus, and diseases which can ruin crops. Stop the cycle of infection by removing these mummies and destroying them, not composting them.

Distorted leaves with red blister-like swellings from leaf curl fungus on a peach tree. (Photo credit: Jack Kelly Clark) Once the tree is dormant (no leaves) you can prune out any dead, diseased or broken branches. Do not seal or paint pruning cuts, leave them open to the air to heal naturally. Sealing or painting these cuts traps moisture and leads to disease. Once all dead, diseased and broken branches are removed prune up to 50 percent of last year’s wood. Pruning your tree produces new growth and opens up the tree to sunlight to produce quality fruit.

Peach branch with approximately 10% of buds at full bloom stage. (Photo credit: Jack Kelly Clark) To prevent leaf curl (fungus) spray before bud swell, which typically occurs after Feb. 14 or Valentine’s Day. Signs of leaf curl are detected on new spring leaves but by then it is too late to control the disease. By planning ahead, you can reduce the likelihood of leaf curl and mitigate its effects on tree growth and fruit production. Some effective fungicide spray materials that are registered for backyard use are bordeaux mixture, fixed copper and chlorothalonil. Always wear proper protective clothing and follow the label when applying any pesticides.

For more information on winter, spring and summer care of your peach and nectarine trees see the University of California Agriculture and Natural Resources (UC ANR) Publication 7261: Peaches and Nectarines: Calendar of Operation for Home Gardeners.

For further assistance contact your local UC Master Gardener Program.

Sources:

January 10, 1996

eaches have been grown in Texas for more than one hundred years. They have become established as commercial crops at Fredericksburg, Tyler, Mexia, Pittsburgh, Weatherford, and Montague, where deep, well-drained soil, proper varieties and chilling, and good orchard management make crops successful. In addition to these factors, the performance of peach trees depends heavily on proper pruning annually.

Peach pruning is a hard, labor-intensive cultural practice that is easy to avoid or compromise. However, if peach trees are left unpruned, the result is weak trees, overproduction, increased disease, and most important, short tree life. Peaches bloom and bear fruit on second-year wood; therefore, the trees need to make good growth each spring and summer to insure a crop for the next year. Each winter, a large number of red 18- to 24-inch shoots need to be present as fruiting wood. If the trees are not pruned annually, the volume of fruiting wood reduces each year, and the fruiting shoots move higher and higher, becoming out of reach. Alternate-year pruning results in excessive growth the year following heavy pruning, so annual, moderate pruning is essential for the long-term control of tree vigor and fruiting wood.

  • Timing Peach Pruning

    Late spring frost is the most significant factor in Texas peach production, and the grower does not want to prune too early. The peach tree will bloom soon after pruning when chilling is satisfied and warm weather follows. Growers with only a few trees can wait until ‘pink bud’ to prune. Growers with large crops should not prune earlier than necessary. Pruning in Texas should occur at least by February, just prior to bloom in March.

  • Objectives of Peach Pruning

    The main idea in pruning is to remove old, gray-colored, slow-growing shoots, which are non-fruitful. However, leave one-year-old, 18- to 24-inch red bearing shoots. Removing 40 percent of the tree annually stimulates new growth each spring. The second objective of pruning is to lower the fruiting zone to a height that makes hand harvesting from the ground possible. A third objective is to open the center of the tree; this increases air circulation, reduces disease pressure, and allows sunlight into the tree to accelerate fruit color. Another goal of pruning is to remove diseased or dead shoots, rootstock suckers, and water shoots.

  • How to Prune a Mature Peach Tree

    Step One.
    Remove all hanger shoots, rootstock suckers, and water sprouts in the lower three feet of the tree. This stripping of lower growth clears a path for herbicide applications, and allows air circulation.

    Step Two.
    Remove all shoots above 7 feet other than red 18- to 24-inch fruiting shoots. Cuts need to be at selected points where the scaffold and sub-scaffold limbs extend upward at a 45- to 50-degree angle. Cuts which leave limbs sideways at a 90-degree angle should be avoided.

    Step Three.
    Remove all shoots which grow toward the inside of the tree.

    Step Four.
    Remove all old, gray wood in the 3- to 7-foot fruit production zone.

  • Additional Hints on Pruning Peaches
    1. Always remove bull shoots in the middle of the trees whenever they develop. Summer pruning immediately after harvest can help reduce bull shoots in the top of the tree.
    2. Wear gloves, long sleeves, eye protection, and caps that cover the ears, to prevent injury.
    3. Pruning paint is not needed.
    4. Peach pruning should remove 40 percent of the tree each winter. This reduces the number of fruit on the tree, and stimulates strong growth of fruiting wood each year.
    5. The key to long peach-tree life in Texas is planting in deep, well-drained, sandy soil, control of peach-tree borer, scale insects, and weeds, and correct pruning. Fruiting will depend on escaping spring frosts.

Cooperative Extension: Tree Fruits

Preparing Trees for Winter

In order to survive freezing temperatures during winter, trees must quickly acquire hardiness in the fall and maintain it until temperatures rise in spring. Trees gradually become winter hardy as they are exposed to cold temperatures, finally becoming fully hardy in early winter. This process begins in the buds and young shoots and progresses into the larger limbs. The trunk is the last part of the tree to acquire hardiness and the most likely to be injured by an early fall freeze. Failure to harden-off before severely cold weather will cause winter injury, but is not a common occurrence in eastern regions of the US. More frequently, warm weather in winter interferes with cold hardiness and predisposes trees to winter injury in March and April. This type of winter injury causes minor injury to some fruit trees, but can be severe about once every ten years.

Good cultural practices hasten hardening-off and reduce the likelihood of damage from fall freezes. Allowing the tree to bear too many fruit will delay the hardening-off process. Apple, pear, plum, and peach fruit should be thinned in early summer so that the tree does not bear an excessive number of fruit. In addition, fruit should be harvested when ripe instead of being left on the tree. Too much nitrogen fertilizer, particularly in summer, stimulates shoot growth and delays hardening-off. Encourage the timely onset of winter hardiness by thinning and harvesting fruit, and by limiting the amount of fertilizer.

Good cultural practices increase the degree of hardiness in midwinter. Good tree care increases the amount of energy stored by the tree, which is used in spring to grow new shoots and to replace tissues that have been killed by winter injury. Over watering, which is very stressful to the roots, limits the level of hardiness the tree can acquire. Fruit trees are more sensitive to excess soil moisture than to drought. Diseases that attack foliage, such as apple scab and peach leaf curl, reduce winter hardiness because of the stress they place on the tree. Disease prevention is an important step in preparing trees for winter. Pruning at the right time of year also promotes winter survival. Pruning causes a small loss of hardiness, so trees should be pruned in late winter or early spring, after the chance for severe temperature has passed. Tender trees such as peaches and trees younger than three years old should be pruned in early spring rather than winter.

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