- Author: Surendra Dara
Novaluron (Rimon 0.83 EC, Chemtura USA Corp, Middlebury, CT) is a popular insecticide used by the strawberry growers for managing nymphal stages of the lygus bug. It is an insect growth regulator that inhibits chitin synthesis and thus interferes with the growth and development of the immature stages. It is effective against egg, nymphal or larval stages. According to some earlier studies, Chemtura restricted the use of adjuvants with novaluron. This has been a concern for the growers especially when novaluron has to be tank mixed with other pesticides and adjuvants. Chemtura's request to amend the label to remove the adjuvant/surfactant statement has been approved by the Environmental Protection Agency (EPA). Growers will soon be able to use adjuvants with novaluron when the new label is ready.
Background about EPA's requirement of adjuvant studies
Unless an adjuvant is not supposed to be used with a pesticide, EPA' s Office of Pesticide Programs (OPP) requires inclusion of adjuvants in the field trials for registering pesticides. This is mainly because of the impact of adjuvants on the pesticide residue levels. Because of this impact, there was a concern in EPA to require new studies with adjuvants for products that were previously registered without the adjuvant data. Crop Life America, Chemical Distributors and Producers Association analyzed historical data from OPP and concluded that adjuvants increase the pesticide residues, but the inherent variability in pesticide residues is more than what is caused by the adjuvants. Based on these analyses, Health Effects Division and Chemistry Science Advisory Council decided not to require new studies with adjuvants for products previously registered without them. As a result when registrants ask for label amendments related to the adjuvant use, EPA would use the fast track process.
What is an agricultural adjuvant?
Adjuvants are substances used with pesticides to improve their efficacy by improving the formulation, atomization, or biological action. Adjuvants act as spreading or wetting agents which reduce foaming, drift, and droplet size and increase the pesticide deposition, retention, and absorption. Agricultural adjuvants are categorized based on the chemical class into surfactants, oils, acidifiers and buffers, fertilizer adjuvants, and others. There are some green adjuvants that are safe to the environment.
Based on how an adjuvant is produced and its impact on the environment, Beck et al (2012) provided a definition for green adjuvants. “According to the production-based approach, adjuvants are deﬁned as green if they are manufactured using renewable raw materials as much as possible while making efﬁcient use of energy, preferably renewable energy. According to the environmental impact approach, adjuvants are deﬁned as green (1) if they have a low human and environmental impact, (2) if they do not increase active ingredient environmental mobility and/or toxicity to humans and non-target organisms, (3) if they do not increase the exposure to these active substances and (4) if they lower the impact of formulated pesticides by enhancing the performance of active ingredients, thus potentially lowering the required dosage of active ingredients.”
Beck, B., W. Steurbaut, and P. Spanoghe. 2012. How to define green adjuvants. Pest. Manag. Sci. 68: 1107-1110.
Grains Research and Development Corporation. 2012. Adjuvants – oils, surfactants and other additives for farm chemicals – revised 2012 edition. Australian Government.
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