Pest Alert: Drosophila Damage Observed in South Carolina Strawberries

— Written By Hannah Burrack
en Español / em Português
Español

El inglés es el idioma de control de esta página. En la medida en que haya algún conflicto entre la traducción al inglés y la traducción, el inglés prevalece.

Al hacer clic en el enlace de traducción se activa un servicio de traducción gratuito para convertir la página al español. Al igual que con cualquier traducción por Internet, la conversión no es sensible al contexto y puede que no traduzca el texto en su significado original. NC State Extension no garantiza la exactitud del texto traducido. Por favor, tenga en cuenta que algunas aplicaciones y/o servicios pueden no funcionar como se espera cuando se traducen.


Português

Inglês é o idioma de controle desta página. Na medida que haja algum conflito entre o texto original em Inglês e a tradução, o Inglês prevalece.

Ao clicar no link de tradução, um serviço gratuito de tradução será ativado para converter a página para o Português. Como em qualquer tradução pela internet, a conversão não é sensivel ao contexto e pode não ocorrer a tradução para o significado orginal. O serviço de Extensão da Carolina do Norte (NC State Extension) não garante a exatidão do texto traduzido. Por favor, observe que algumas funções ou serviços podem não funcionar como esperado após a tradução.


English

English is the controlling language of this page. To the extent there is any conflict between the English text and the translation, English controls.

Clicking on the translation link activates a free translation service to convert the page to Spanish. As with any Internet translation, the conversion is not context-sensitive and may not translate the text to its original meaning. NC State Extension does not guarantee the accuracy of the translated text. Please note that some applications and/or services may not function as expected when translated.

Collapse ▲

Last week, South Carolina cooperative extension personnel issued a pest alert for drosophila damage in strawberries. It is impossible to visually distinguish drosophila larvae between species, but if fruit appear otherwise undamaged (meaning they have no holes, rotted areas, or disease damage) except for a soft spot with larvae underneath, it is very likely that those larvae are spotted wing drosophila (SWD).

In recent years, SWD damage has not been common in spring fruit strawberries, although they have been more common later in the season and in day neutral plantings. Our warm winter and spring weather has likely shifted infestation risk to earlier this growing season. Given the greater likelihood of SWD damage in spring fruiting berries, what should strawberry and early blueberry growers do to prepare?

When infestation risk is low (such as during recent spring strawberry seasons), growers should monitor for adult flies and begin insecticide treatments when they are detected. However, risk this year, appears higher, and I would encourage growers to consider taking preventative management action in addition to monitoring for adult flies. Preventive management consists of: Weekly applications of registered pesticides, reapplied in the event of rain. Rotate between at least two modes of action to reduce the likelihood of resistance development. See the Southern Region Small Fruit Integrated Pest Management Guides for recommended insecticides.

Even if fruit are being managed preventatively, growers should still sample fruit to determine if it is infested. Sample fruit at each harvest via salt water extraction or by cutting fruit open to observe larvae. Salt water will cause larvae to exit fruit as illustrated in the video below. Sample at least 30 berries per field. See more larval sampling information.

If growers find damaged fruit, what should they do? I put together these suggestions a few years ago, including:

1. Remove ripe fruit and ripening fruit starting to change color and destroy it (by freezing, “baking” in the sun inside a clear plastic bag for a few days, or removing from the site). Eggs or larvae may be present in otherwise sound appearing fruit. Leaving this fruit means that potentially infested fruit is present and could be harvested.

2. Begin an aggressive spray program as described above.

3. Practice excellent sanitation. Thoroughly harvest all fruit and sell or destroy it. Destroy culled fruit. Unpicked fruit is a reservoir for SWD larvae. Clean up after rain, and send a clean up crew after you-pickers.

4. Sample fruit each harvest as described above.

5. Consider trapping flies using yeast and sugar baits or commercially available lures. Traps tell you SWD presence or absence and are not perfect, but they can be helpful if damage has not already occurred in fruit. Place traps in strawberry rows, near fruit for the best chance of catching flies. Currently available traps are not helpful in making management decisions once damage has already occurred.

I will post more information as the North Carolina strawberry harvest begins and we have a sense of what our actually damage scenario looks like.

Update, 28 March 2016

It is also important to note that many broad spectrum insecticides, such as those recommended for SWD, can flare spider mites! See considerations when making these applications.

More information

Written By

Hannah Burrack, N.C. Cooperative ExtensionDr. Hannah BurrackProfessor & Extension Specialist and Director of Education & Outreach, NC PSI Call Dr. Hannah Email Dr. Hannah Entomology & Plant Pathology
NC State Extension, NC State University
Updated on Mar 28, 2016
Was the information on this page helpful? Yes check No close
Scannable QR Code to Access Electronic Version