Once again, Oklahoma’s unpredictable weather has hit many of our state’s fruit and pecan growers. If the negative February temperatures did not affect the fruit buds and, in some cases, mature wood, the late April spring freeze may have wreaked havoc on the upcoming crop.

I have heard from many that their peach trees did not bloom this season. For early blooming fruit trees like peach, nectarine, and especially almond and apricots, the loss of the fruit crop is usually the result of a late spring freeze event. This year for many peach and nectarine growers, the winter temperatures in February were just too cold and damaged the fruit buds prior to bud swell. When the trees began to push buds, only leaf buds were seen. The fruit buds or blooms did not break because they were severely damaged. I was amazed to see several apricot trees flowering in March. Apparently, apricot dormant buds are more cold hardy than peach. Now, that does not indicate that we will have apricots but there is a chance unless they were damaged by the recent April 21 freezing temperatures. Some pictures surfaced on Facebook of peaches that were flowering but most that I have observed were not. Why the difference? Well in some cases, those peaches that did flower were seen in towns and neighborhoods where the trees were in warmer micro-climates that protected the buds.

Apples, pears and cherries seem to have fared better. These types of fruit trees have higher chilling requirements and do not normally bloom as early but are also better adapted during dormancy for cold winter temperatures. The fruit development in some areas may be affected by the mid-20 temperatures experienced on April 21. Cell damage to the fruit can cause misshapen fruit but it is too early to tell just yet.

Wind machines, helicopters, propane heaters, and burning haybales were being used in different areas of the state on April 21 to try to protect different fruit crops. Some growers were successful and protected the crop and some methods did not produce the results that they had hoped. Mixing the warm layers of air with the colder layers near the ground when using wind machines and helicopters can raise the temperatures a couple of degrees. Two to three degrees may be enough to save a crop of peaches or pecans. In pecan orchards, it is not uncommon to see the lower half of a tree lose the crop and the upper half produce a large crop due to the radiational freezes settling near the ground. Mixing the air can give some protection when the right air inversions in place.

Frequently I receive questions about using sprinklers for freeze protection. Watering the ground underneath the trees a few days prior to a spring freeze will allow the soil to stay warmer. Wet ground can hold more heat while dry ground will cool off more quickly. Plants in areas with sandy soils may have more damage than clay soils due to water holding capacity and heat storage. Spraying the trees once prior to a freeze really will not give much protection. The energy or heat released is made possible due to the water freezing. So, for sprinkler freeze protection, the water must be continuously freezing during the critical temperatures until the temperatures warm above freezing. This can be difficult to accomplish due to the amount of water needed or the amount of ice building up on the trees. Once the water stops sprinkling and freezing, the heat protection stops.

Site selection and surrounding areas can make a big difference in how much damage may be received due to cold temperatures. Higher elevations and sloping areas will benefit in that cold air, like water, flows downhill and collects in the lowest areas. If your pecan orchard or vineyard is at the bottom of a valley or hill, there is nowhere for the cold air to go and it will fill up the site with cold air. If the site is on a hillside or at the top of a hill, the cold air can settle away from the planting site and can protect the plants. Be aware that even though the plants are on a hill, something impeding the cold air can have the same effect as being at the bottom of the hill. An overgrown fence row, brush pile, building or anything that slows down the cold air from draining can cause it to pool on the side or top of the hill which can result in cold injury. This was recently observed at the Cimarron Valley Research Station where brush piles kept cold air up on the higher pecan orchard causing more damage than the lower orchard that had air drainage available.

Many vineyards reported freeze damage from both winter and spring freeze events. Those vines with severe winter injury (many European grapes) may need to be replaced or if new growth sprouts from ownrooted vines, they can be re-trained. Those vines that lost new shoot growth may have an opportunity to still produce a crop. Some varieties will produce on secondary buds but not all types.

Pecan growers will need to assess their damage. If female flowers were killed, the potential crop will be lost. Careful observation for an upper crop should be made. Continued zinc applications when new growth begins will help with replacing new healthy foliage. If the 2021 crop is lost, trees should continue to be managed with reduced inputs since next year’s crop can be affected by management this season.

For more information as always feel free to contact your local county OSU Extension offices. In Hughes county we are in the courthouse, and in Seminole county we are 1 mile west of Wewoka on between HWY 59 and Business 270. Feel free to stop buy and visit about your fruit and net trees anytime you are in the area.