Research has led to changes in the production practices of citrus since HLB was introduced to Florida. Nutrient rates, applications, irrigation timing and managing soil pH are all important to the best health of citrus trees, especially those that are HLB infected. The citrus greening disease is so prevalent in the state that it’s likely your trees are infected, or will become infected, with HLB. Keeping up on soil and foliar fertilizing programs will lead to better outcomes in the long run.
The third edition of “Nutrition of Florida Citrus Trees” was recently published by UF/IFAS. This is an important look at new developments in research and how proper nutrition helps HLB infected trees maintain better health. The second edition was published back in 2008, so it’s time to take a closer look at your citrus fertility recommendations and make sure they are up to date with the latest knowledge.
High soil pH due to dissolved bicarbonates reduces the availability of important nutrients to your trees by decreasing the root lifespan and function. Soil and water quality should be managed frequently to maintain a soil pH of 6.0-6.5, to combat this issue. Adding compost to the soil can help reduce Nitrogen and Phosphorus losses, as it has the potential to improve root health by providing a complex, slow-release carbon source to feed beneficial soil microorganisms.
HLB-infected trees need the right type of fertilizer, at the right time, rate, and location near the roots to be used efficiently. Controlled-release and liquid fertilizers work best to satisfy this nutrient demand through the roots. A five-year study of foliar applications on citrus trees shows this to be an effective complement to soil fertilizations in nutrient availability and can increase yields 10%-25%.
Water management is crucial for HLB-infected trees too. A field study in Florida commercial citrus groves showed healthy trees took up 25% more water than HLB-infected trees. Reducing your water schedule by 10%-20% could help root health and increase water and nutrient uptake.
This updated edition details special situations like CUPS Production Systems for HLB-free trees. This system requires different techniques, equipment and approaches than open-air citrus operations. Precision irrigation, hydroponic systems, electronic soil water sensing, fertigation and canopy management are carefully maintained to maximize plant growth and yield, with nutrients being delivered in real time.
The citrus manual is available now through the UF/IFAS website. It could become part of the “Florida Best Management Practices Citrus Manual” this year.