Keeping your crops healthy throughout the year is not easy. Numerous threats pose risks to your plants, from pests and weather events to equipment failures. Unfortunately, many of these threats are outside your control as a grower. However, there are prevention and management strategies to help mitigate crop damage. This time of year, one of a grower’s biggest concerns is frost damage.
What is frost?
Simply put, frost is a form of frozen water — specifically, frozen water vapor. Frost forms when the air temperature drops below the dew point, where air is cool enough to turn water vapor within that air into liquid. Once temperatures are cool enough, this liquid water crystallizes into ice. Frost typically forms on solid objects saturated with moisture, like windows, cars, and plants, and in lower-lying areas like valleys.
What is Frost Damage?
The problem with frost is that it can damage your crops. When water freezes, it expands. When a plant is saturated with water and temperatures drop below freezing, the moisture within the plant expands as it forms ice crystals, which can damage plant tissue. Certain crops are more frost resistant than others. In the case of fruit trees, ripened fruit is more frost tolerant because the fruit’s sugars act as an antifreeze. However, fruits are still less frost tolerant than leaves, and fruited trees are less cold-resistant than fruitless trees.Growers may anticipate frost during winter, but certain weather events can also bring frigid temperatures in the spring and autumn. Depending on where you are in California, the frost season varies. Awareness is essential for protecting your crops, so today, we’re going to look at signs of frost damage on your crops and how you can prevent it.
Signs of Frost Damage
You might wonder what frost damage looks like on your crops. Typically, frost will damage leaves and new growth first, so look for wilting that turns black, brown, and crispy. At this point, the leaves are dead. For woody plants and trees, frost can damage the trunks and branches. You may observe splits or cracks in tree trunks. Young trees are more susceptible to this type of damage and are at the top of your priority list regarding protection and frost prevention. It’s rare for frost to kill mature trees.
Frost damage may not show up right away. If you are caught unawares by frost, but your plants seem okay immediately after, keep your eye on them as signs of damage may show up later. For example, you might notice white or yellow marks around the leaf veins, where cells have died. If you’re heading into winter after a dry fall without adequate irrigation, the ground will likely freeze to a lower depth than soil with sufficient water, and this freezing can damage the roots of your plants. If your plant roots have been damaged by the cold, the plant will likely dry out, so look for signs of desiccation, like discolored leaves or needles.
If you produce citrus and your trees are fruiting, fruits will appear dry when frost damage occurs. Frost-damaged fruits can be salvaged but are more susceptible to bacteria and fungi within a few weeks.
There are a few steps you can take to prevent frost damage to your crops, starting with a thorough understanding of your growing climate and property.
Know your crops’ critical temperature
First, it’s important to understand at what temperature your crops will experience frost damage. This is called the critical temperature, and it varies by species. Some species are generally more cold-hardy, such as kumquats and mandarins, which can tolerate temperatures down to 20 degrees for a few hours before damage occurs. On the other hand, frost begins to damage lemons at 26 degrees. For your reference, this helpful publication from the University of California has a chart of select citrus plants and their critical temperatures.
Optimize your planting site
Plants exposed to prevailing winds are more likely to experience frost damage than crops protected by geography or other plants. Therefore, if you produce frost-sensitive crops, avoid planting them in the lowest parts of your property, where moisture will settle and freeze, or along the exterior of your property in unprotected areas.
Soil moisture management
If you’re expecting freezing temperatures, irrigate your crops at least three days before. Moist soil will retain more heat than dry soil. In addition, proper irrigation over the entire year will make your plants healthier and hardier and more able to withstand frost than weakened or under-watered plants. Check out our tips on irrigating sustainably to strike the right balance between adequate irrigation and saving water and money.
Cover your sensitive plants
You can protect sensitive crops from frost damage by covering them loosely but securely. If you wrap a tree tightly, for instance, air won’t have any space to circulate and warm the plant. So instead, you can use cloth wraps or tents to cover your trees, securing the edges with heavy items. In addition, frost monitors can alert your smart farming systems when frigid temperatures are on their way.
Help with your winter crop protection
At Fruit Growers Supply, we are here to help you do your job year-round, through every season. Our dedicated experts have decades of experience under their belts and would be happy to help set you up with everything you need to protect your crops from frost damage this winter. Have questions or want to chat about frost solutions? We’re happy to help – stop by one of our supply stores or fill out our contact form by clicking below.
Have any questions? We’re happy to help – stop in one of our supply stores today, or fill out our contact form by clicking below.