Maximize Spring Bud Break Vigor with Post-Harvest Applications of Potassium

Potassium (K) is one of the most essential nutrients associated with tree and vine production, and it is commonly the most misapplied. Lack of K early in fruit/nut development can lead to smaller fruit/nuts, lower TSS/sugars in grapes, uneven ripening, and poor color development. Leaf deficiencies result in necrosis (cell death) of leaf tips and margins, beginning on older leaves, as well as increased susceptibility to water stress and plant pathogens.  The addition of K during the post-harvest root flush period can provide trees/vines with the reservoir of K they need for a strong budbreak/flowering in the Spring.  In plants, K is involved in many essential functions, including:

• Regulating water pressure in plant cells, affecting cell extension, gas exchange, and movement of leaves in response to light
• Activating enzymes that help facilitate chemical reactions
• Synthesizing proteins
• Adjusting pH within plant cells
• Increasing carbon dioxide fixation during photosynthesis
• Transporting chemical compounds
• Balancing electrical charges in various parts of cells

Potassium is generally readily available in most soils. However, trees and vines usually can’t uptake enough K to satisfy crop requirements during peak demand. This spike in demand starts just before fruit/nut set, continues through sizing, and then peaks again prior to dormancy. Since K moves into the roots through diffusion (very short distances in the soil), drought, deficit irrigation, high salinity, sandy soils and high soil levels of calcium and magnesium can all adversely affect K uptake. The key concept in potassium fertility is getting readily available K into the tree/vine early and often so the plant has time to metabolize it and actively translocate carbohydrates to the fruit/nuts, as well as internal storage structures.

Fortunately, Helena has the tools to mitigate K deficiencies and effectively maximize the K you apply. A two-pronged peak demand program (prior to fruit set and pre-dormancy) efficiently delivers optimum K to the trees/vines in a timely fashion.

A major challenge for conventional potassium fertilizers is increasing the mobility of K in the soil. In Helena’s soil-applied portion of the program, Nucleus 0-0-21 or Nucleus 0-0-15 is recommended. These Nucleus products utilize Kalium Formulation Technology to increase the solubility and mobility of potassium in the soil. This package overcomes fertilizer inefficiencies and K fixation by soil colloids. Another benefit is unsurpassed compatibility with other liquid fertilizers, making it an ideal blending partner.

This results in trees/vines receiving the K they require during the most critical times of fruit/nut development and pre-dormancy storage.

- Paul W. Crout, CCA, PCA, Helena Product Manager and Agronomist