Asian Citrus Psyllid Distribution and Management
University of California
Asian Citrus Psyllid Distribution and Management

Residual Activity of Insecticides

Residual Activity of Insecticides

Psyllid adults fly into orchards from outside and the eggs and nymphs are tucked inside newly forming leaves that are difficult to reach with insecticides. In addition, those new leaves are growing rapidly and often outgrow the insecticides.   Thus, the best insecticides are those that are translaminar or systemic and/or that have a long residual life.  The pyrethroids and neonicotinoids and their combinations are the longest lasting insecticides and that is why they are considered the most effective.  The soft insecticides such as abamectin, and organic insecticides such as Pyganic are very short lived.  They must make contact with the insect to kill it and there are virtually no residues.  This chart is evolving as we learn more about the level of kill various insecticides provide in grower orchards.  It is meant as a guide, in that insecticides with long residual are the best for situations such as eradicative efforts, very high psyllid densities, bulk citrus and in HLB quarantine areas.  The softer, short residual insecticides work acceptably when the psyllid populations are low.  The short residual insecticides need to be applied frequently to have an effect.  

This chart will change as we learn more about the response of psyllids to insecticides in California.

Residual activity of insecticides

 

Webmaster Email: robjohnson@ucanr.edu