One of the themes that emerged during the citrus seminars at the Citrus & Specialty Crop Expo was that integration of multiple strategies is needed to keep HLB-infected trees productive. Davie Kadyampakeni’s talk detailed the five Rs of sustainable citrus production in the era of HLB. Kadyampakeni is an associate professor at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center in Lake Alfred.
- RIGHT WATER MANAGEMENT
The right water management includes use of soil moisture sensors and daily irrigation. Frequent irrigation is key to optimal tree performance, and daily irrigation results in improved nutrient uptake, said Kadyampakeni. However, in the case of ½ inch or greater rainfall, irrigation should be avoided for two days. - RIGHT NUTRIENT RATE
Nitrogen and phosphorus rates are currently under revision, but growers can still apply nitrogen at 180 to 200 pounds per acre along with the current UF/IFAS recommendations for phosphorus, Kadyampakeni advised. Some other nutrients can be applied at elevated levels for bearing trees impacted by HLB. This includes 3 pounds per acre boron, 15 pounds per acre zinc and manganese, and 10 pounds per acre iron. - RIGHT FERTILIZER PLACEMENT
For ground application of granular of slow-release fertilizer, Kadyampakeni said to place the fertilizer in the irrigated zone or where the microjet wetting pattern is. These fertilizers should have polymer-coated micros for better efficacy on HLB trees. To improve plant uptake, he encouraged the use of foliar fertilizer for micronutrients and selected macronutrients like potassium and calcium for soils with high pH (>7). Combined application of ground and foliar fertilizer was also recommended. - RIGHT FERTILIZER SOURCE
Improved fertilizer blends resulted in better root growth efficiency and higher fruit yields. A blend of 9-1-14, 11 calcium, 7.6 sulfur, 2 magnesium, .08 zinc, .04 manganese and .025 boron, applied with 180 pounds nitrogen per acre annually, resulted in two times greater root density compared to a blend of 16-2-16 with other nutrients applied separately. - RIGHT TIMING
Kadyampakeni recommended the following timing for fertilizer applications:- Fertigation: Apply weekly, biweekly or monthly
- Slow-release or controlled-release fertilizer – Apply two to three times per year (February, May and September)
- Conventional granular fertilizer – Apply in four splits per year (February, April, May and September)
- Foliar fertilizer – Apply three to four times per year in February/March, April/May and August/September
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