Microjet sprinklers provide the most effective way for producers in the cold-hardy citrus region to protect their trees from freeze damage. Microjet irrigation is even more effective than drip irrigation and overhead irrigation.
Mary Sutton, University of Georgia (UGA) assistant professor and citrus Extension specialist, stressed that point during the recent Georgia-Florida Irrigation Expo at the UGA Vidalia Onion and Vegetable Research Center in Lyons, Georgia.
“With freeze protection, the goal is to protect the graft union and as much of the lower scaffold branches as possible. We’ve found that microjet sprinklers provide the most coverage of that area,” Sutton said. “With overhead irrigation, you’re really hitting the top of the canopy. You get ice formation up there, you can get limb breakage up there, and you’re not getting that water on your graft union. With drip irrigation, you don’t get that same coverage of the whole trunk and those lower scaffold limbs.”
Florida citrus producers only have to look at this past season to see how freezing temperatures can impact trees. The Florida Department of Agriculture and Consumer Services released preliminary estimates of agriculture losses from winter storms Ezra and Gianna. Estimated total citrus damage is $674.66 million.
Sutton explained how irrigation protects trees from dangerously low temperatures.
“The biggest thing is the water tends to be warmer because it’s coming from a well or other source. So, you have heat that way. As ice forms, it’s also going to release a little heat, so you’re getting heat that way. And then you have an igloo effect as that ice forms,” Sutton said. “All of that is going to keep the tree temperature a little bit higher than the ambient temperature, and sometimes that’s all we need is for it to be at 32 degrees versus 28 or 26 degrees.”
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