Strawberries, raspberries, blueberries and blackberries grown in Santa Cruz and Monterey Counties host a number of tortricid, or leafroller, species, most common of which is the orange tortrix, Argyrotaenia franciscana. Adult orange totrix are active in early spring and all stages are present pretty well through the season. Larval feeding can damage flowers, developing green fruit and sometimes larvae will tunnel into ripe fruit. During picking, some orange tortrix larvae can become dislodged and fall into the harvest trays, causing significant losses in marketability if discovered.
The increasing problem of the light brown apple moth, Epiphyas postvittana, should be of great interest to all berry growers in the Santa Cruz and Monterey County production district. While light brown apple moth (LBAM) is a leafroller like orange tortrix and normally would present a similar pest problem as the orange tortrix described above, this pales in comparison to the fact that it is a regulated pest under quarantine and consequently demands a totally different pest management perspective.
LBAM is unlike other leafrollers in the Central Coast district because the threshold for regulatory action is a single larva. In other words, the discovery of a single larva in a production field will result in significant regulatory scrutiny of the field where it was discovered, most often meaning close inspection of harvested fruit, as well as mandatory applications of pesticides, usually being Bt, spinosyns or oils. Thus it is in the grower’s best interest to lower the probability of LBAM presence in the field to as close to zero as possible.
Work done by this office and a private industry researcher on orange totrix in blackberries in 2008 indicate that spinetoram (Delegate), spinosad (Success or Entrust) and Bt (Dipel) are all good in controlling leafrollers. Whether it was three applications made at two week intervals begun at first detection of leafrollers early in the season 63 days prior to harvest, or two applications made at seven day intervals begun two weeks prior to harvest, leafroller populations were profoundly reduced or even eradicated in treated plots.
While the current issue of LBAM magnifies the problem of leafrollers in berries, growers currently do have the tools to address it directly.
There are pesticides mentioned for management of leafrollers in this article. Before using any of these products, check with your local Agricultural Commissioner's Office and consult product labels for current status of product registration, restrictions, and use information.
Light brown apple moth larva.
Orange tortryx emerging from blackberry fruit.