0 The Low-Down on Chemical Constituents

Many turfgrass professionals are often confused by the constituents of the products that they are using, be they fertilizers, pesticides or herbicides. Terms such as fillers, carriers and inert materials are common components of many product labels. Many users harbour a great deal of uncertainty about the exact nature of these products, with many feeling that they may be just taking up space in the product container or bag. However, in many instances these products are playing a pivotal role of the efficacy of the product involved.

Fertilisers

In day to day turfgrass management, various fertilisers are commonly used. Urea, which contains 46% nitrogen, is a frequently used fertiliser, although the constituents of the remaining 54% are often unknown. In many instances, a filler is added to fertilisers, whereby a substance, usually inert is added to give bulk to the product. As well as this, fillers are often used to prevent caking of fertilisers, which basically relates to the sticking together of the fertiliser granules.

Caking or clumping of the nutrients would be a big problem were it not for such additions, particularly with water soluble fertiliser products such as ammonium nitrate and potassium nitrate. There are other fertilisers on the market, that are classifies as lightweight. These nutrient products consist of the nutrient impregnated into a light weight carrier, such as vermiculite, bentonite, peat or foam.

These carriers help to aid even distribution of the nutrients, and without them it would almost be impossible to evenly apply such fertilisers. Fillers may or may not have some value as a source of plant nutrients. Some manufacturers include micronutrients in the filler, such as iron, zinc, copper, manganese, chlorine, molybdenum and boron, which are required in very minute quantities.


Pesticides, Herbicides and Fungicides

Common components in the above chemicals used on turfgrass include:
§ Active ingredient: The active ingredient commonly referred to as the A.I. This term refers to the amount of pure chemical contained within the product that is providing the activity against the pest, weed or fungus. Typically, the amount of pure A.I. is very low and would be almost impossible to apply without some form of dilution.
§ Solvent: The solvent is a compound used to dissolve the active ingredient. Some common solvents are acetone, and varsol.
§ Synergist: This is a chemical which, when mixed with the product, may increase the products effectiveness.
§ Emulsifier: An emulsifier is a chemical which allows an oil and water to mix.
§ Spreader: An adjuvant which allows the material to spread over the leaves, by lowering the surface tension.
§ Diluent: Ingredients which dilute the ingredients to a desired level.

Chemical formulations for various aspects of turfgrass management can be supplied in different forms including:

§ Dusts often contain the active ingredient mixed with compounds such as organic flour, sands and talc which may aid even distribution

§ Emulsifiable concentrates contain active ingredients mixed with solvents such as oil, as well as emulsifiers which aid in the active ingredient and solvent to dissolve in water and be spread evenly.

§ Wettable powders usually include some form of wetting agent, which allow the A.I. particles to become suspended in water at the time of application and without which even application would be virtually impossible.

Adjuvants are often included in pesticide products and are aimed at altering the spreading characteristics of spray droplets in order to improve product safety and performance. Wetting agents, emulsifiers, spreaders, buffering agents, spreader-stickers drift reduction agents, and buffers are commonly used adjuvants.

Buffering agents adjust the pH of alkaline (high pH) water, which unless treated can cause hydrolysis of pesticides, leading to pesticide inactivation. Antifoaming agents are sometimes required in products which require shaking prior to use, such as flowables. Without the antifoaming agents, such products would be a nightmare to handle. Microbial growth can be an issue with some water based products and biocides are sometimes included to prevent microbial growth, which would decompose the A.I. contained within the product. For foliar acting chemicals, ingredients are often included to reduce U.V. degradation and increase rain-fastness.

It is important to remember that not all ingredients are compatible. Some products may react with others leading to poor mixing and flocculation or clumping of ingredients leading to sprayer blockages and poor, uneven application. This is why compatibility testing using methods, such as the jar test, are recommended when mixing certain products.

Tim Butler MSU
About the Author

Tim Butler is currently studying for a doctorate degree in Turfgrass Science at both University College Dublin, Ireland, and Michigan State University, USA. Contact Tim at timmbutler@hotmail.com

References

Potter, D.A. 1998. Destructive Turfgrass Insects; Biology, Diagnosis and Control. Ann Arbor Press.
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