With global population growth expected to reach an estimated 9.7 billion by 2050, how worldwide food production may be augmented to meet the needs of an expanding international community continues to be a hot topic of discussion among agricultural field experts. The process of identifying alternative methods for plant production that are adequate and economically viable, without significantly raising public food costs, is an ongoing challenge for today’s farmers. To date, the use of pesticides has remained the predominant method for preserving and ensuring the evolution of the world’s food supply due to their overall effectiveness and affordability. However, despite the success of a wide range of pesticides that include insecticides, herbicides and fungicides, plants still exhibit many natural barriers that directly affect the retention, entry and transport of these substances. The main barrier to pesticide movement into the plant is a waxy layer, called the cuticle, which covers the entire plant surface and serves to prevent water loss. As a result, pesticides applied to the leaves of plants generally face greater obstacles than those applied to soil. In an effort to combat these barriers, specialized additives, referred to as surfactants, may be added to spray solutions to improve the emulsifying, spreading, sticking and absorbing properties of liquids. Pesticides formulated or applied with surfactants reduce surface tension within the external surface layers of water and allow for more effective movement of the pesticide through the cuticle.
Surfactants At Work:
Surfactants (aka: surface-active agents) can be classified into 4 primary classes including non-ionic, anionic, cationic and amphoteric that differ according to the electrical charge on the hydrophilic (“water-loving”) end of the molecule. As a general rule, non-ionic surfactants are the safest to use and the most versatile, accounting for nearly 50% of surfactant production. Due to their lack of an electrical charge, non-ionic surfactants can be used with any product because there are no positive or negative ions to react with the active chemical with which they are being mixed. By reducing the surface tension of the spray solution, surfactants flatten the water droplets, thus spreading the pesticide on the leaf surface. This allows more surface area for the chemical to come in contact with the leaf, allowing chemicals to saturate plant leaves instead of beading up and running off. Products such as Schaeffer Wet-Sol also help increase nutrient uptake in soil by increasing mass flow. Soil becomes hydrophobic and water repelling when organic coatings from decomposing matter such as roots and shoots build up on soil particles, causing water to repel from its surface. Such water run-off in the top inch of the soil profile can leave behind localized dry spots and result in the uneven penetration of water throughout the soil. Soil surfactants act as a bridge between the organic coatings and water to help aid in its penetration and retention, allowing for a more even distribution of water and nutrients.
Make The Most Of What You’ve Got:
Variations in plant species such as wax content and composition, leaf arrangement and architecture, and plant hairs, are among the various features that can affect the overall performance of surfactants. To optimize the performance benefits of these specialized additives, surfactant solubility should complement the solubility characteristics of the selected pesticide. In other words, both the surfactant and pesticide should be oil-soluble or water-soluble. Additionally, environmental conditions should not be overlooked, as plant cuticles are generally thicker and harder to penetrate under low humidity conditions while thin, relatively permeable cuticles are favored by high humidity and high moisture conditions.
Reap What You Sow:
Without a doubt, the science of surfactant technology has increased the effectiveness of pesticides. However, caution must be taken to ensure that the proper surfactants are selected, as damage to plants can occur when not utilized properly. Be sure to read labels carefully. When applied at too high a rate, there is an increased risk of toxicity to the plant’s leaves and roots as well as potential membrane permeability damage. When used as directed, however, non-ionic surfactants provide a safe, stable and highly effective solution for farmers seeking to meet the nutritional demands of an ever-growing population.
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