Description of the Pest
Omnivorous leafroller is the most common and damaging of the leafrolling caterpillars. Omnivorous leafrollercaterpillars may differ in body color from cream to brown with light brown to black head capsules and resemble other tortricid species, except that they have white, slightly convex and oval tubercles at the base of each bristle on the upper side of the abdomen. Vineyards may be infested with omnivorous leafroller moths that develop on host plants outside the vineyard. Omnivorous leafroller has four to six generations per year depending on climatic conditions.
Fruittree leafroller, obliquebanded leafroller, and orange tortrix may also attack kiwifruit. Fruittreeleafroller is a minor pest of kiwifruit that only has one generation per year. Overwintering eggs hatch in spring, and larvae can be found feeding on leaves until about June. The larvae are dark green caterpillars with black heads. Adult moths appear in June or July and lay the overwintering eggs. Obliquebandedleafroller may be the most common leafrollerfound in the Sacramento Valley. It has two generations per year in the Sacramento Valley. Larvae are green to tan-colored caterpillars. Orange tortrix is mostly found in the cool, coastal regions where it has two to four generations per year. The larvae vary in color but are generally yellowish tan to light brown.
Omnivorous leafroller and the other leafrollingcaterpillars directly damage fruit by scarring the surface when they feed.
Closely examine blossoms and vegetative shoots in the vineyard during prebloomand bloom for the presence of caterpillars, webbed leaves, or feeding damage. If present, or if leafroller damage was evident in previous harvest, a postbloom treatment is justified. This postbloom treatment is often sufficient to keep leafrollers under control for the remainder of the season.
Decisions to treat summer generations of the omnivorous leafrollershould be based on the presence of caterpillars observed from periodic visual inspection of the vines, not from moths caught in traps. No correlation exists between pheromone trap catches of adult moths and damage. However, the timing of treatment should be based on trap catches.
Organically Acceptable Methods
Applications of Bacillus thuringiensis are acceptable in an organically certified crop.
Monitoring and Treatment Decisions
Treat for omnivorous or obliquebanded leafroller at bloom if the vineyard has a history of this pest or if a serious infestation occurred in the previous season. Otherwise, monitor to determine the need for treatment. There is not enough research in kiwifruit regarding monitoring; therefore for omnivorous leafroller, refer to the monitoring information used in grapes. For the obliquebanded leafroller use managing information found in peaches.
Use pheromone traps, degree-days, and monitoring to assess omnivorous and obliquebanded leafroller treatment timing and populations.
Place pheromone traps in the vineyard just before budbreak, and check traps twice a week. Information obtained from trap catches is used to establish a biofix, which is an identifiable point in the life cycle of this pest. The biofix is the first night moths are consistently caught in traps. Continue to monitor with pheromone traps through fruit set to track adult flights of subsequent generations. For information on placing and monitoring traps in a vineyard, see the PHEROMONE TRAPS section in the Grapes Pest Management Guidelines.
|Common name||Amount per acre||REI‡||PHI‡|
|(Example trade name)||(hours)||(days)|
|Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, the pesticide's properties, and application timing. Always read the label of the product being listed.|
|A.||BACILLUS THURINGIENSIS ssp. KURSTAKI#|
|(various products)||Label rates||4||0|
|MODE-OF-ACTION GROUP NUMBER1: 11A|
|COMMENTS: Apply at end of hatch. Most effective on small caterpillars at low rates. Repeat a low application rate in 5 to 10 days or a high rate will be required on large larvae. Does not disrupt natural enemies.|
|(Prokil Cryolite 96)||6–8 lb||12||30|
|MODE-OF-ACTION GROUP NUMBER1: 8C|
|COMMENTS: Ground application only in up to 200 gal spray/acre. No more than four applications per season at 15- to 30-day intervals.|
|(Asana XL)*||9.6 fl oz||12||14|
|MODE-OF-ACTION GROUP NUMBER1: 3A|
|COMMENTS: For use when severe damage is occurring. Only effective when temperature is above 75°F. Do not exceed seven applications per season or spray at less than a 7-day interval.|
|*||Permit required from county agricultural commissioner for purchase or use.|
|‡||Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.|
|#||Acceptable for organically grown produce.|
|1||Rotate chemicals with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; chemicals with a 1B group number should be alternated with chemicals that have a group number other than 1B. Mode-of-action group numbers are assigned by IRAC (Insecticide Resistance Action Committee).|