KAC Citrus Entomology
University of California
KAC Citrus Entomology

Insecticide Resistance Monitoring

Lorsban Resistance Bioassay

Lorsban bioassay of 1st instar nymphs
Lorsban bioassay of 1st instar nymphs
We conduct the Lorsban resistance monitoring by collecting citricola scale-infested leaves from the orchards, we circle the scales on the leaves, dip the leaves in a concentration of Lorsban that kills susceptible scales and then wait 5 days to see what the level of survival is. 

Resistance Monitoring Results

Citricola scale resistance 2006-09
Resistance monitoring of 98 populations of citricola scale in the San Joaquin Valley during 2006-2009 revealed that some populations show up to 60% survival of the test concentration of Lorsban.  This indicates that Lorsban resistance is a problem for some populations of citricola scale in this region.  Growers should manage Lorsban resistance by alternating with insecticides in other chemical groups.  Table of citrus pesticide groups.

Contact us for Lorsban Resistance Testing of your Citricola Scale

The Citrus Entomology Lab is accepting samples of citricola scale-infested leavesf or Lorsban resistance assays.  If you provide us a map of the location and the pesticide history of the block, then we will collect the leaves and run the test.  This test is best done during June-August when the scales are young.  If you have one or more orchards that have citricola scale that you would like to have tested, please contact Greg Montez at 559-646-6597 or gregm@uckac.edu

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