Magnesium is needed for many processes in plants, most importantly chlorophyll production. Deficiencies in magnesium cause interveinal chlorosis. Older leaves begin to turn yellow while the veins remain green. If the deficiency is severe, younger leaves will begin to turn yellow as well. The yellowing or chlorosis is caused by reduced chlorophyll production which leads to reduced photosynthesis and reduced carbohydrate production. In citrus, magnesium supports fruit fill, fruit size and quality.
Phosphorus deficiency effects include poor crop vigor and energy transfer in plants as well as reduced root growth. Symptoms begin at the mature leaves. They partly turn yellow to purple. Where the deficiency is severe, small brownish to bronze freckles occur over the leaf blades. Phosphorus levels should be 10-15% of N levels and 50% of Mg levels for optimum plant performance.
There is a synergy with foliar phosphorus and magnesium applications. Applying them together has a greater effect than one or the other. Magnesium increases photosynthesis and phosphorus increases energy and carbohydrate production. Together they amplify plant and crop growth.
Trials have shown that applying magnesium to citrus has provided significant yield increases, mainly due to increased fruit weight. Optimum use of magnesium also boosts juice content of the fruit. Because this nutrient is needed throughout the main fruiting season, a constant supply is required.
The correct balance of phosphorus to other nutrients is critical in citrus production. It is particularly important during early tree growth on new groves. Regular phosphorus applications will maintain the yield and fruit quality of mature citrus trees. Availability is important during periods of active root growth, for example, spring time and vegetative flushes.
YaraVita® BUD BUILDER™WP has a unique analysis. It has the highest magnesium on the market at 24%. Phosphorus 6% works synergistically with magnesium. Furthermore, it has nutrient value added with 10% zinc and 3% boron. This entire formulation increases carbohydrate production, translocation and storage, supporting this year’s crop as well as next year’s.
Sales Agronomist at Yara North America - South Central Valley, California
YaraVita Product Specialist - California