Proper Foliar Feeding Methodology
The advent of post-emergence foliar applied herbicides in the late 20th century began to open the agricultural world’s door to the effectiveness of foliar applied products. Since GMS has always been intended to be foliar applied our question was never “if” it worked but rather the specifics of what makes the right product for foliar application and how can we properly apply it. This is why we put such emphasis on proper foliar technique in each Summer Solution: Both the product in use and the conditions in which it is sprayed will have a large effect on the final results.
As we have demonstrated in our past several articles on foliar feeding (see the Summer Solutions for the past several years), foliar feeding positively impacts root mass, soil biology, and is itself impacted by the water it is mixed with (if it is mixed). However, these benefits will not come from spraying any product. GMS’ hot-mix manufacturing process, use of high-grade orthophosphate, and balance of micronutrients deserve a lot of credit for its success in foliar applications. The hot-mix procedure ensures that all of the elements in GMS are tightly bonded to each other, such that they will not settle out and will be pulled uniformly into the plant with the phosphorus. Likewise, a high-quality orthophosphate is easily absorbed and easily used by a plant, without the need for soil microbes to first convert it. Lastly, we have seen in lab work that GMS micronutrient package encourages early root growth. The following directions provide a good reminder of some important considerations when you are going out to spray.
Photo A: Dissolved Solids in Water
Amount of Precipitation of Various Water Sources When Mixed with GMS at a 15 to 1 Ratio (Mall Gooding) 1 Minute After Adding 1 Cup of Growers lo 15 Cups of Waler
Washing and Mixing Precautions
Since many people’s sprayers are used for multiple products, including fertility and various pest and weed control products, it is important to remember to wash out your sprayer of old product before going out to spray GMS. This is for two reasons: 1) even residual amounts of herbicides, such as that left in the lines or lining the inside of a tank, are strong enough to seriously damage or kill non-resistant crops if accidentally sprayed onto them. This is especially important with newer technologies, including glyphosphate, dicamba, and 2-4D mixtures. Please follow proper tank cleaning protocols in order to avoid crop damage. 2) GMS is unpredictable in how it will react to or affect herbicides when they are mixed. Just as when mixing with some hard water, there may be precipitate that will cause efficiency and equipment problems. Also, some operators have noticed an increase in herbicide potency when mixed with GMS, causing even resistant crops some problems. It is not advisable to tank mix GMS with any other product.
Fine Mist
Foliar feeding with fertility products is most successful when as much of the plant as possible is coated in as fine a mist as possible. The pores in leaves’ cuticles are very small and so will absorb small water particles much better than large ones. Spray pressures over 40 psi tend to produce the smallest particles. In addition, if spray drift is a concern, tend towards higher spray pressures for the anti-drift type of nozzle you are using. Remember, plants can absorb nutrition through their leaves and through smooth bark/stalks, so getting as much coverage as possible is in your best interest.
Spray Timing
Foliar spraying should not be done in the heat of the day or in direct sunlight. This is because foliar nutrition must be absorbed through pores in the leaf surface, which will close in high heat or sunlight to prevent water loss from the plant, thereby preventing them from absorbing anything on their surface. Furthermore, since foliar nutrition must be absorbed with water through the plant surface, we advise that you spray when there is or will shortly be dew on it. Taking these together, the best times to spray are early morning, late evening, on overcast or foggy days, or anytime the leaves will have dew on them. If you do spray in high heat or direct sunlight, the risks of leaf burn and bad fertilizer efficiency are high.
Spraying GMS straight or Diluted
GMS can be sprayed straight or be diluted in water. In the early days of the company, when low-volume sprayers were more commonplace, spraying GMS straight was by far the most popular choice. Since the use of foliar applied herbicides and fungicides has become widespread higher volume sprayers have become more the norm. In such a case, GMS can be mixed with water to meet volume requirements. Spraying straight or diluted does not affect the effectiveness of GMS, barring if water of poor quality is used.
If you are going to mix GMS with water, it is best to use R.O., distilled, or rainwater because they contain little to no dissolved solids. The phosphorus in GMS can react poorly with the various elements in hard water, creating a white precipitate that reduces efficiency and can plug up sprayer screens and nozzles. However, if you keep the amount of water added under the amount of GMS, this should not be a problem.
Water Quality Considerations
In the past we recommended that, if you were going to mix GMS with hard water, you acidify the water first to ensure it wouldn’t react with the GMS and produce a precipitate. Acidifying the water will prevent the phosphorus and various elements from bonding together and precipitating out. While this will ensure that the mixture makes it through your screens and nozzles, research done over the past year and a half has shown that even if the water and GMS don’t react, there is still a detrimental effect on the leaf from using hard water. The mineral left on the leaf surface from the hard water can impair photosynthetic potential, so it is important to use clean, low dissolved solid water to ensure no harm comes to the plant and you get the most out of GMS. We are finding that even water sources that have been treated either by a municipality or in a water softener and other in-home treatment equipment (excluding an R.O. system) may have detrimental effects on the leaf surface. This is for the same reason hard water can harm leaf surfaces: Whatever mineral is in the water that is not absorbed by the plant will remain on the leaf surface.
This is an exert from the Summer Growers Solution (2024) written by Zach Smith, Product & Training Specialist
Signup for our newsletter to stay in the loop
