SAT, NOV 21 2009
11:31:29
Tuesday February 10 2009
With the potential of the new fruit fly, Drosophila biarmipes, to become a problem in the Watsonville- Salinas fruit production district, it is important for growers to know what they might do to control it. The pesticides Malathion and Pyganic offer a measure of control against adult flies, and will need to be applied frequently, meaning once every week to 10 days.
Another pesticide which has been used with significant success in other areas of the country suffering fruit fly infestations is GF120 Naturalyte Fruit Fly Bait. Since it is a bait, GF120 is used differently than other pesticides, and it is worthwhile reviewing this with applicators and growers.
Being a bait means that GF120 draws the target pest to it, instead of having the pesticide delivered to the pest. This means that coverage and distribution is far less important with GF120 than with regular pesticides.
Indeed, this is the case because in most cases the application rate of GF120 plus water carrier is less than one gallon per acre. Obviously, it will not be possible to apply GF120 with an airblast or rowcrop sprayer because the rate is so low. One must use equipment which can apply very low rates, such as the hand held sprayer pictured below, to apply this material. There are also automated sprayers in use in the Central Valley for olive fruit fly control specifically for application of this bait.
Distribution of GF120 means applying a spot (around 2-3 milliliters) of the material (see second photo below) over fairly widely spaced intervals in the field. In the trial conducted this past winter, it was found that every thirty feet on each side of a raspberry hedgerow was sufficient to reach the rate required by the label.
While there are no restrictions on the label concerning contact of GF120 with berry fruit, it is suggested to avoid contacting the fruit with the bait as it does not taste very good. In raspberries, spray to the base of the hedgerow some two to three feet off of the ground. This seems to be where most of the flies are found anyway, so this serves a second purpose. In strawberries, it is probably best to spray between the plants during the early part of the season when the canopy has yet to close and then towards the midtier where there is less fruit when the plants are larger.
Mixing of GF120 is important. While soluble in water, it takes significant agitation to go into solution, more so than most other pesticides. It is vital that GF120 be properly mixed, because unsuspecting applicators could end up applying the bulk of the active ingredient in the first run of the application and water on the rest. Additionally, it is very thick when not well mixed and clog the lines. Once properly mixed, it does not come out of solution.
Finally, the label for GF120 recommends re-application every one to two weeks, depending on weather conditions. Rain will wash the bait off and sun breaks it down over time. Our experience in macro-tunnels informs us that the bait lasts longer in the protection of the tunnels, but even so, it is advisable to re-apply every three to four weeks.
There are several insecticides mentioned for control of fruit flies in this article. Before using any insecticides, check with your local Agricultural Commissioner's Office and consult product labels for current status of product registration, restrictions, and use information.
Photo courtesy of Ed Show- Driscoll Strawberry Associates
Photo courtesy of Ed Show- Driscoll Strawberry Associates
Photo courtesy of Ed Show- Driscoll Strawberry Associates
Tuesday January 27 2009
Please be informed that this year's Annual Strawberry Production Meeting for the Central Coast will be held on February 5 at the Elk's Lodge in Watsonville, the same place as last year.
Follow the link below for the announcement and agenda:
https://ucanr.org/sitebuilder/filegroups/calendar26-Jan-09-1643/11711.pdf
Friday December 5 2008
Raspberry sawfly, Monophadnoides geniculatus, is an uncommon pest in raspberries on the Central Coast of California. I recently had a question concerning this pest, so it something worth discussing.
Raspberry sawflies are not flies, but actually wasps. The larvae, since they are fixed on the leaves and damage them, draw our attention as pests. Larvae are usually found on leaf undersides, are ½ of an inch long, light green in color, and have a brown stripe down the back. Larvae generally occur in groups, so a closely spaced group of punctures and holes in the leaves should be a signal to look for raspberry sawfly.
Being very mobile, the adults are seen far less. The adult wasps are flattish and have a thick body roughly ¼ of an inch long. Female adults also have a yellow white band across the back of the abdomen.
In almost all cases, sawflies do not merit control, since in a light to moderate infestation, sawfly larvae will make a few holes in the leaves and not compromise fruit yield. However, more severe infestations, of the sort that we have not yet seen on the Central Coast, have the potential of eating all the leaves and seriously damaging the plant.
Probably the most important point of this writing is that growers do not confuse raspberry sawfly larvae with more damaging moth larvae, since chemicals used to control them can be different.
Photo Courtesy Maxwell Norton, UCCE
Photo Courtesy Maxwell Norton, UCCE
Photo Courtesy UC IPM
Friday November 21 2008
During the last two months, this office has had many samples of strawberry and raspberry fruit infested with fruit fly larvae submitted. What has been notable about this species of fruit fly is that it is infesting maturing fruit, rather than over-ripe and rotten fruit, as is the case with the vinegar fly that we are all accustomed with.
These new fruit flies found this fall have been found in very high numbers in strawberry and caneberry fields northeast of Watsonville.
The new species of fruit fly is Drosophila suzukii (misidentified in November 2008 as Drosophila biarmipes). Adults of this fruit fly found are almost identical to the regular vinegar fly, Drosophila melanogaster, with the exception that the males have one black spot on the back portion of each wing.
I have submitted samples to the California Department of Pesticide Regulation and found that this fruit fly is not new to California. It is categorized as a Class ‘C’ pest and is not subject to any exceptional regulatory scrutiny.
It is imperative that growers look for this fruit fly early on next year, and take steps to control it early, before it becomes a pest of the proportions it has been this year.
It is advisable not to leave strawberries and caneberries to continue to fruit without harvest over the winter, as it is suspected that the D. suzukii will continue to breed and multiply in these areas. Having large numbers of this pest overwinter will only exacerbate problems next year.
While the embedded larvae are not controlled short of destroying the fruit, the adults are relatively easy to control with pesticides. Malathion is effective for conventional growers, and Pyganic is very effective for organic growers. Since only the adults are being controlled with pesticide applications, multiple applications spaced 7 to 10 days apart will probably be best for long term control.
There are several insecticides mentioned for control of fruit flies in this article. Before using any insecticides, check with your local Agricultural Commissioner's Office and consult product labels for current status of product registration, restrictions, and use information.
Photo courtesy of Ed Show- Driscoll Strawberry Associates
Photo courtesy of Ed Show- Driscoll Strawberry Associates
Photo courtesy of Ed Show- Driscoll Strawberry Associates
Drosophila biarmipes larvae in fruit
