Strawberries and Caneberries - Agriculture and Natural Resources Blogs

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Author: Mark Bolda

Published on: June 1, 2009

It is very important to know that what has been identified in this blog as Drosophila biarmipes in this post is actually Drosophila suzukii. From this point on, all posts referring to the new species of vinegar fly will refer to Drosophila suzukii.

Photo Courtesy Ed Show

Male Drosophila suzukii on raspberry fruit. Note black spots at ends of wings which distinguish this species from other vinegar flies.

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Leafrollers in Raspberries

Author: Mark Bolda

Published on: May 28, 2009

Lately there has been some concern about leafrollers in raspberries, so it is important first for growers to know how to identify what a leafroller looks like in order to make correct pest management decisions.

Leafrollers are generally true to their name, meaning they will roll leaves up to form a shelter with a whitish webbing. They will also form shelters between several leaves, growing points of plants, developing flowers and fruit. This is a sure way to distinguish leafroller larvae from other larval pests in the caneberry field.

The leafroller larvae themselves in raspberries are green in color and will move about vigorously (if healthy) when disturbed. This compares to other larval pests found in caneberries which are either sluggish to respond or a distinct method of movement, such as the looper described below.

It is important to note that it is almost impossible to distinguish leafroller species from one another in the field. Generally, identification of leafrollers needs to be done under a microscope or through DNA analysis, and indeed this has been the case lately with light brown apple moth.

Leaf folded in manner typical of leafroller

Punctured flower of raspberry from leafroller activity

Dead leafroller in several leaves webbed together

Leafroller found in growing point of raspberry

Feeding damage not typical of leafroller.

Note how holes on leaves are spread out over leaf area, and no webbing found.

Looper

Looper larva found on raspberry leaves not exhibiting damage typical of leafrollers. Larva in picture was disturbed just moments before photo was taken, and note how it is assuming a curled position. This is definitely not a leafroller.

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A Word on Managing Leafrollers, Including the Light Brown Apple Moth, in Strawberries, Raspberries and Blackberries

Author: Mark Bolda

Published on: May 26, 2009

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.