by Norman D. Wilson, Ph.D.

The use of foliar feeding to increase yields, improve quality, and enhance pest and stress resistance is a proven technology which has become a customary production practice on many crops. Foliar feeding has been demonstrated to be especially profitable to fruit, vegetable, nut, and fiber producers. Successful managers recognize the efficiency and profitability of foliar feeding to produce high yielding top quality crops.

The benefits of foliar feeding are numerous and obvious to discerning growers. Foliar feeding produces quick and visible results. Foliar applications can be targeted to a specific stage of crop development or to achieve specific objectives. The efficiency of foliar fertilizer applications can be as high as 95% and the efficiency will always be significantly higher when compared to soil applied fertilizer. Foliar applied products can be used to quickly correct a nutrient imbalance and stimulate the plant to increase nutrient uptake from the root system. Foliar feeding can compensate for reduced root uptake and is an excellent way to combat short term environmental or pest related stress.

Nutritionally balanced crops are less subject to insect and disease damage and research has demonstrated that several plant nutrients are directly related to insect and disease resistance. In order to be most effective, these nutrients may need to be present in leaves and other plant tissue at higher concentrations than would normally be achieved with root uptake alone. Foliar application may be the only method to elevate such nutrients to sufficiently high levels to utilize the natural protection that all plants possess. ViGorator from ViTech Industries is a balanced foliar formulation containing most of the essential major and micro nutrients. ViGorator can be applied alone or as a “base” product to which other ViTech Foliar Nutrients can be added to correct specific deficiencies or elevate specific nutrients.

Foliar feeding is by far the most efficient way to supply essential micro nutrients. Just as the name suggests, crops require micro nutrients in small amounts compared to other nutrients. Application of only ounces per acre of micro nutrient fertilizer in millions of pounds of soil can result in the nutrient becoming “lost” to chemical or physical tie up.  Foliar applied nutrients can aid in the uptake and utilization of soil applied fertilizer and provide an excellent way to “fine tune” a high fertility program. ViTech Industries produces a complete line of complexed micro nutrients specifically formulated for foliar feeding. Especially in the case of micro nutrients, isn’t it logical to feed the crop rather than fertilize the soil?

Foliar applications are a particularly effective method of matching nutrients with specific developmental stages of a crop. Manipulation of nutrient levels in this manner can be used to produce desired responses such as increased bud development, more fruit retention, faster sizing, enhanced quality factors, and preconditioning of trees and perennial crops for dormancy. Careful attention to timing, rates, and frequency of application is necessary to achieve expected results. Leaf analyses are an excellent tool when determining rate and time of application. ViTech Foliar Products specifically designed for these uses include ViBurst, a fruiting cycle product, and ViFinisher, a late season yield and quality enhancing product.

Plants absorb foliar applied nutrients through any above ground part including leaves, stems, fruit, and even flowers. However, the aerial parts of plants are not necessarily designed for mineral nutrient uptake. The external wall of leaf epidermal cells is covered by a cuticle layer composed of wax and cutin. The cuticle acts as a hydrophobic barrier to prevent excessive moisture loss and limits entry of foreign substances. Unfortunately, the cuticle can also serve as an effective barrier limiting absorption of foliar applied fertilizer. To be effective, any foliar nutrient product must penetrate the epidermal barrier and quickly translocate to interior leaf cells. Systemic uptake and rapid metabolism of applied nutrients prevent a concentration gradient block which can restrict further absorption. Plant leaves differentially accept mineral nutrients and most nutrients will not enter leaf tissue in significant amounts without the aid of an effective carrier. The nature of the foliar carrier is by far the most important consideration when choosing a foliar product. Very high analysis products are not advantageous and may be counter productive. High nitrogen foliars in particular can disrupt epidermal cell membranes resulting in dehydration and death (leaf burn). The phytotoxicity associated with some foliar products is due to this type reaction. ViTech ViCare is a highly effective foliar carrier which utilizes low molecular weight organic acids, natural oils, and enzyme systems to buffer and complex nutrients, penetrate epidermal cells, and quickly translocate  absorbed nutrients to other areas of the leaf for assimilation. ViCare acts as a respiratory catalyst to improve nutrient assimilation and photosynthesis. ViCare is available as a carrier product and is a constituent of other ViTech foliar products including ViGorator, ViBurst, and ViFinisher. ViCare can also be tank mixed to enhance the activity of most fungicides, insecticides, herbicides, and plant growth regulators. Because ViCare can quickly and efficiently translocate foliar applied materials, it should be considered an integral part of any nutritionally based disease management program. Other ViTech products important in pest management include Potassium, Sulfur, Copper, Calcium, Boron, Cobalt, and Silica.

The actual crop response from a foliar application can depend upon several factors including the type carrier used, the nutrient form, application method, nutritional status of the crop, soil moisture level, and overall metabolic activity in the crop. Environmental factors including air temperature, humidity, and wind speed can also influence effectiveness. ViTech field consultants use soil and tissue analyses, past crop response, present condition of the crop, and intended response to make specific foliar recommendations.

ViTechFoliar Products are liquid concentrates that should be diluted with water before application. Dilution to a concentration of 10% or less (one quart of ViTech Foliar Product in three or more gallons of total solution) will ensure uniform coverage without leaf burn. Foliar applications will be most effective when made early in the morning after sunrise or late in the evening before sunset.