Its supposed to get really cold this weekend. Here is the breakdown on how the cold will affect certain crops.

Citrus: Properly hardened bearing trees will withstand temperatures as low as 19°F to 20°F without appreciable wood damage. Citrus fruits, on the other hand, easily freeze at 26°F to 28°F, especially when these temperatures last for several hours. An active freeze protection strategy used in Georgia are microjets placed next to the graft union with a minimum of 15 gallons per hour with a 90 degree spray pattern per tree for freeze protection. The temperature of the well water (approximately 65°F) is beneficial as it hits the tree. Do not use overhead irrigation for freeze protection as it will result in limb breakage.

Corn: Corn can withstand cold up to 28°F. If it gets between 24°-28°F for more than 2 hours we have a problem. If its stays at 31°F for more than 4 hours we have a problem. There is nothing you can do. The rain passing through will wet the soil which will help some as moist soil retains heat. It will take 4 or 5 days after the cold event to determine the severity of the damage.

Pecans: Dormant pecan buds can easily handle 24°F but green pecan tissues freeze at around 26°F. On most trees, pecan bud development has not yet advanced to a stage that I would be overly concerned about. If you have buds that have started to elongate, especially if they have pushed the outer scale off completely, even if the green buds are still somewhat compressed tightly, they could still be at risk of damage if temps get down to 26°F. But we haven’t seen many trees at this stage yet. Any foliage that has expanded will likely take a hit if we see temps in the 26°F-28°F range for a few hours. Even if you have foliage expanding in this situation and it gets killed by the freeze, that foliage will regrow as long as the wood is not damaged. Damage to the pecan wood is of some concern for nursery trees and moreso for newly planted orchard trees and those in the 1-3 yr old range. The most common injury on such trees occurs when the sun warms tree bark during the day and then the bark rapidly cools after sunset. These abrupt fluctuations are most common on south or southwest sides of trunks and branches, and they may kill the inner bark in those areas. Young and/or thin-barked trees are most susceptible to this type of injury especially as the sap begins to flow. Injury may not be visible initially and often shows up a few days to weeks later and will be detected by a browning of the cambium layer as you cut into the bark of the tree. Healthy cambium tissue will appear green. Sometimes the injured area of the trunk takes on a sunken or water soaked appearance. Trunk protectors will help minimize this type of injury on young orchard trees. Rapid expansion and contraction of water within the wood and bark, particularly under falling night temperatures, can also sometimes result in cracks that may appear on trunks of young trees and also on the branches of older trees. These may be a few inches long and are often found on the southwest side of the tree. These cracks may heal over a little in the summer and can re-open again in winter. When we have freeze injury to young trees, it sometimes is not detected for a considerable length of time, sometimes 2-3 years, as there is often enough healthy cambium to keep the trees going to a point and then they outgrow the cambium they have left, which can no longer support them, causing the trees to collapse. When this occurs the foliage usually turns brown and the tree may die suddenly. This usually shows up in May or June as the heat and water demand ramp up. Overall, I expect damage to be minimal, if any to mature pecan trees. We will likely see some injury to young (newly planted-3 yr) trees in some areas if temperatures drop as low as we see forecast and they remain there for several hours.

Peanuts: Pray

Wheat: Same as corn. If wheat is in the boot stage it will get some help form the leaf sheath but if the heads are exposed they are susceptible to cold damage.

Posted in: