We are evaluating systemic insecticides for the management of current and newly emerging pests of California avocados. Current management practices for avocado thrips are centered on the use of foliar insecticides. Several foliar treatments are available (Agri-Mek, Delegate and Danitol) for the control of avocado thrips. However, the number of products is limited, the mode of application can be difficult (helicopter use on steep hillsides, applications near urban regions), and there are risks of resistance development, particularly to Agri-Mek due to it also being used against persea mite during the summer, and to Danitol (based on its use in other systems). Systemic neonicotinoid insecticides are relatively easy to apply (via established sprinkler irrigation systems or by modern trunk injection systems), and have a mode of action that has not been in use for the management of avocado thrips.
A new mode of action would substantially lower the resistance risk associated with Agri-Mek (and generics), and alleviate operational difficulties in the use of foliar treatments. In this project, we are evaluating 3 modes of application for systemic neonicotinoids – soil drench, trunk injection and basal trunk applications (trunk sprays or trunk paints). Our major focus during the current year of the project will be to evaluate basal trunk sprays of imidacloprid (not registered for grower use due to the method of application) and clothianidin (not registered on avocados as yet). Our research has shown that both chemicals are toxic to avocado thrips and the purpose of this research is to determine whether basal trunk sprays can deliver the required amounts of insecticide to the leaves to kill the insects.
