Citrus Peelminer - Pesticide Trials
Research by Dr. Beth Grafton-Cardwell and Chris
Reagan (UC Kearney Ag Center), with assistance from Pest Management Associates
and Badger Farming.
A number of Pest Control Advisors, as well as my research team have conducted several pesticide trials to see if we can stop the spread of citrus peelminer. The general protocol has been to spray as soon as mines are detected. The results have been very disappointing. One or more of us have tried Admire, Provado, Supracide, Lorsban, Sevin, Success, Oil, Danitol, Baythroid, Agri-Mek, as well as a number of unregistered insecticides with and without oil. Some of these insecticides killed larvae that were mining the fruit (Success, Provado, Lorsban) but the effect seemed to last only 2-3 weeks and then new mines began to appear on new fruit. Pest control advisors have observed that higher rates of oil (1%) in combination with an insecticide seemed to improve kill. Admire slowed larval growth a bit but did not prevent mining. If growers want to control this pest chemically, they will need to spray every three weeks. This is not a good prospect for either the pocketbook or the citrus IPM program. The long-term plan for controlling this pest is to release the parasite Cirrospilus coachellae (Peelminer parasites.)
Pesticide Trial 1
The figure below shows the data for a trial in which individual grapefruit trees in the Lindsay area were hand-sprayed (300 gpa) with various registered and unregistered insecticides (5 trees per treatment) on July 13, 2001. A 0.5% concentration of oil or CS7 was added to each insecticide. The only treatment that completely stopped new mines from appearing was Micromite (diflubenzuron) and the effect lasted only for 2 weeks. After 4 weeks Micromite stopped controlling the peelminer, probably because the fruit was growing rapidly and so provided untreated rind. Micromite is not currently registered for citrus in California. We have more trials planned using large plot sizes that may give us somewhat better control.
Pesticide Trial 2
This trial was conducted with the excellent help of a number of entomologists from the University of California, Pest Management Associates and Badger Farming. The figure below shows the data for a trial in which 6 rows of Fukomoto navel trees in the Exeter area were treated using a speedsprayer (150 gpa) with various registered on August 16, 2001. Half of the acreage had already been treated with 32 oz of Admire, which only slightly slowed the peelminer down. Treatments included: Success (6 oz) + 0.5% oil, Lorsban (4pts), Esteem (16 oz) + 0.5% or 2.5% oil, Baythroid (6.4 oz) + 0.5% oil, Agri-Mek (10 oz) + 0.5% oil and an untreated control. None of the insecticides significantly reduced the number of new mines found in the fruit 2 weeks after the treatment was applied. We resampled several of the treatments after 4 weeks and still saw increases in mined fruit. These are very discouraging results and demonstrate how important the success of the parasite releases will be.
