Dormant Season Pyrethroid Sprays
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Dormant Pyrethroid Sprays
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Pyrethroids can be used for peach twig borer in the delayed-dormant or dormant season. Check with your PCA to determine the proper pyrethroid for your situation.
Nuts should be monitored for the presence or indication of larvae. If monitoring indicates that any of the pest species require additional control measures later, they can be applied in-season.
Residues of the pyrethroid insecticides permethrin and esfenvalerate persist on bark and may impact naturally occurring predator mites for extended periods of time after dormant season and in-season applications.
Mite outbreaks caused by use of pyrethroids may require additional miticide treatments over and above those normally applied.
Some registered products are not widely used in the dormant season because of possible effects on non-target organisms or because of label restrictions. Check the label for any restrictions.
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Precautions
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If a pyrethroid is applied as a dormant spray, precautions should be taken to prevent movement into surface waters. CURES new booklet, "Pyrethroid Insecticides - Orchard Crops" provides many recommendations for avoiding the movement of pyrethroids into surface waters. Laboratory exposures indicate that fish and invertebrates are particularly sensitive to pyrethroids. Pyrethroid insecticides adhere strongly to soil particles and therefore have the potential to be carried off-site by sediment runoff rather than moving dissolved in water. Sediment toxicity may result after pyrethroids are transported into water bodies. If so, they may be bioavailable to fish in water or to invertebrates in sediment.
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Potential for Resistance
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While pyrethroids remain effective for controlling peach twig borers in most areas, greatly increased tolerance by peach twig borer to pyrethroids has been identified in the Sacramento Valley, raising the possibility of resistance.
In general, insects become resistant to pyrethroids more rapidly than other classes of pesticides.
Some registered products are not widely used in the dormant season because of possible effects on non-target organisms or because of label restrictions.
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