Agricultural compositions including herbicides, for example, compositions containing N-(phosphonomethyl)glycine (“glyphosate”) are typically applied to target plants by spraying. Spraying is typically performed from aircraft, tractors, ground rigs, irrigation systems or railcars. A portion of the spray droplets are typically very small, for example, less than about 200 microns, which are subject to off-target movement, termed “drift”. Drift is undesirable because it reduces the amount of active applied to the target plant and risks unintended application of the active herbicide, pesticide, fungicide or the like to non-target plants. Further, spray droplets are subject to rebound or splashing after the droplets initially impact the target plants, which results in a reduction or loss of active ingredient on the target plants. This also raises economical and environmental concerns, as more of the spray droplets splash or rebound to the ground or on non-targeted plants.
Common approaches to reducing drift and rebound are to add one or more deposition control agents (in a concentrated liquid or dry adjuvant composition), for example, polysaccharides, polyacrylamides, to the agricultural composition. However, for such deposition control agents to properly hydrate into an aqueous solution, a relatively high amount of diammonium sulfate must also be added with the addition of the deposition control agent.
Current commercially available guar-based drift control dry adjuvant compositions comprise a large amount of salts such as diammonium sulfate. These commercially available dry adjuvant compositions generally comprise more than 85% of diammonium sulfate and less than about 10%, typically 5%, guar, by weight of the total composition. In these commercially available compositions, the high weight percentage of diammonium sulfate is important and necessary relative to the guar to ensure proper dispersion and hydration of the drift reducing agent in the aqueous tank mix. As a consequence, not more than a relatively low amount of guar (relative to the amount of diammonium sulfate) can be added to such adjuvant composition. Thus, the total amount of adjuvant composition per volume of tank mixture (i.e., the “use rate”) as described above must be high in order to add an effective amount of drift control agent to the tank mixture.
As such, these formulations are commonly used with suggested high use rates (e.g., 9 lb/100 gallons), since to mix an effective amount of a drift-control agent such as guar to a tax mixture, a substantially higher amount of diammonium sulfate must be added. There are drawbacks associated with such high use rate formulation such as the costs and resources necessary for shipping and handling a large amount of material for large commercial applications, as well as the costs and resources required for storage.
It is therefore desirable to have low use rate formulations wherein a lower amount of diammonium sulfate or salt mixtures are utilized (i.e., can sufficiently hydrate the drift-control agent such as guar) relative to the guar and/or its derivatives. In some cases, however, such formulations with a proportionally higher guar to diammonium sulfate percentage cannot disperse and hydrate properly. Reference is made to high use rate formulations described in U.S. Pat. No. 6,358,294 to Latting. Insufficient dispersion of dry guar gum and/or its derivatives can result in the agglomeration and lumps of guar gel or “fish-eyes,” which can lead to among other things clogging of the spray nozzles during spray application.
Accordingly, there remains a continuing interest in efficient, improved application and preparation of agricultural compositions, typically the preparation of drift and/or deposition control adjuvant composition with low use rate, ensuring proper dispersion and hydration in agricultural actives, especially glyphosate and/or glyphosate heel solutions.