See tips for getting the most out of foliar fertilizer applications when you add them to your nutrient management program.

In our last blog post, we shared the benefits of foliar fertilizer applications from a Citrus Industry article; in short, foliar nutrient applications are “a key factor to stimulate the natural defense mechanisms of their trees, to induce pest and disease tolerance, and to improve fruit yield and fruit quality.” The article, written by Mongi Zekri, a UF/IFAS multi-county citrus Extension agent in LaBelle, also shared tips for optimizing foliar fertilizer applications. See them below.

Tips for Foliar Fertilizer Applications

While the article advises that growers should still use soil applications for macronutrients nitrogen (N), potassium (K) and phosphorus (P), it shares that “foliar applications of macronutrients can, however, be alternatively applied in sufficient quantities to influence both yield and fruit quality. Citrus trees can have a large part of the annual N requirements met through foliar applications. Foliar applications of other macronutrients [calcium (Ca), magnesium (Mg) and sulfur (S)] and micronutrients [zinc (Zn), manganese (Mn), copper (Cu), boron (B) and molybdenum (Mo)] have proven to be an excellent means for satisfying citrus tree requirements.”

Tips from the article include:

  • “Foliar-applied nutrients prior to a rainfall are subject to being washed off the leaves and onto the soil.”
  • “It can burn leaves at certain rates under certain environmental conditions,” such as “Stressful conditions like dry winds, disease infection, and unfavorable soil conditions.”
  • “Applications when the weather is hot (above 85 F) should be avoided. This means that during warm seasons, applications should be made in the morning or evening when the temperature is right, wind is minimal and the stomates on citrus leaves are open, allowing leaves to efficiently exchange water and air.”
  • “Nutrient absorption is increased when spray coverage reaches the undersides of the leaves where the stomates are located.”
  • “Favorable results from foliar feeding are most likely to occur when the total leaf area is large.”
  • “Foliar applications of micronutrients, with the exception of iron, are more effective and efficient when the spring, summer and fall new flush leaves are about fully expanded.”
  • “Applications should be at least two weeks apart to give the tree sufficient time to metabolize the nutrients and deal with the added osmotic stress.
  • “To be efficient and to avoid crop damage, dilute solutions of nutrient formulations are recommended.”
  • The pH of the spray solution should be between 5.5 and 6.5.
  • “In order to enhance uptake and thus the effectiveness of any foliar application, N should be added to the solution. Urea may be the most suitable N source for foliar applications due to its low salt index and high solubility in comparison with other N sources. Urea has been shown to stimulate absorption of other nutrients by increasing the permeability of leaf tissue. However, the urea utilized in foliar sprays should be low in biuret content (0.2% or less) to avoid leaf burn.”

Griffin Fertilizer offers traditional soil-based fertilizers and foliar fertilizers, such as Griffin 400 MZF, a liquid foliar fertilizer containing manganese, zinc, and iron. It is formulated to correct and prevent deficiencies in citrus. Urea is included to aid in uptake.

Griffin Fertilizer is committed to helping both growers and ranchers make sound agronomic and economic decisions in order to maximize the health of their grove and pasture. As a full-service custom dry & liquid fertilizer blender and crop protection product distributor, we will continue our mission to further advance Florida agriculture. For questions -or concerns about your farm or pasture, contact us and one of our team will be in touch.