Environ. Horticulture, Pears, Cherries, and Viticulture
University of California
Environ. Horticulture, Pears, Cherries, and Viticulture

Strawberries

Drosophila suzukii update

The following refers to trap counts taken on June 2 of Drosophila suzukii, previously (incorrectly) identified in this post as Drosophila biarmipes.

Several raspberry fields have fairly high counts of D. suzukii now.  One in the vicinity of Peckham Rd and another on Riverside Rd have counts in excess of 50 D. suzukii males (identified by the spots on the back of each wing) per trap, numbers which would be consistent with some fruit damage.  Another raspberry planting on Thompson Rd also has seen an increase to 28  male flies found in one trap.  It is recommended in these cases to start a program of control.

Two farms which have been applying GF 120 fruit fly bait since the end of March/ beginning of April have seen sharp reductions in the numbers of D. melanogaster and D. suzukii trapped.  While this is not a controlled study with an untreated check, it does suggest that consistent, weekly applications of GF 120 fruit fly bait are useful in reducing numbers of this pest.

Another point of interest is that one raspberry plantation that had increasing numbers of vinegar flies (both D. melanogaster and D. suzukii) made a series of 3 applications of Entrust (which contains the same active ingredient as GF 120 fruit fly bait) over a two week period to control leaf rollers.   The last trap reading had a single vinegar fly found, again suggesting some effect of this pesticide on the vinegar fly population.  However, this is not a trial with an untreated control, so this evidence should be understood as being anecdotal only.

To date, blackberry fields have had very few flies trapped.

There are pesticides mentioned for management of vinegar flies 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.

 

Posted on Wednesday, June 3, 2009 at 9:39 AM

Drosophila suzukii

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
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.

Posted on Monday, June 1, 2009 at 5:31 PM

Leafrollers in Raspberries

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
Leaf folded in manner typical of leafroller

Punctured flower of raspberry from leafroller activity
Punctured flower of raspberry from leafroller activity

Dead leafroller in several leaves webbed together
Dead leafroller in several leaves webbed together

Leafroller found in growing point of raspberry
Leafroller found in growing point of raspberry

Feeding damage not typical of leafroller.
Feeding damage not typical of leafroller.

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

Looper
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.

Posted on Thursday, May 28, 2009 at 12:10 PM

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

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.
 

Photo Courtesy UCCE
Photo Courtesy UCCE

Light brown apple moth larva.

Photo Courtesy Ed Show
Photo Courtesy Ed Show

Orange tortryx emerging from blackberry fruit.

Posted on Tuesday, May 26, 2009 at 5:33 PM

Monterey Bay Academy Field Day

Please be aware that the Monterey Bay Academy Field Day will take place this coming June 19.  Click the link below to access the agenda:

http://ucanr.org/mbameeting

Don't miss this one!

Posted on Tuesday, May 19, 2009 at 4:21 PM

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