The Australian Pesticides and Veterinary Medicines Authority (APVMA) has proposed to approve Syngenta’s Callisto Herbicide (480 g/L mesotrione) and the new active constituent, mesotrione.
The proposed product Callisto Herbicide is intended for pre-emergent control of a range of broadleaf weeds in wheat and barley.
Mesotrione is a member of triketone class of herbicides that inhibits the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD), the second enzyme in the catabolic pathway of tyrosine. In susceptible plants, inhibitors of HPPD prevent carotenoid pigment formation, which in turn leads to chlorophyll degradation. The active is absorbed through the roots and affected plants will turn white or pale yellow before finally being controlled, because susceptible plants (which excludes barley and wheat) become chlorotic as they are unable to detoxify mesotrione. Mesotrione is slightly soluble in nature and may redistribute through the soil profile depending on soil texture, soil organic matter and rainfall patterns. For weed resistance management mesotrione is a Group H herbicide.
The product is currently registered as Callisto herbicide (480 g/L mesotrione, SC formulation) in: Argentina, Belarus, Bosnia and Herzegovina, Botswana, Brazil, Canada, Chile, China, Colombia, Croatia, Czech Republic, Ecuador, France, Hungary, Italy, Macedonia, Mexico, Mozambique, Serbia, Slovenia, South Africa, South Korea, Turkey and the United States of America.
Public comments will be closed on 17 December 2019.