Spotted winged Drosophila

Pest of thin-skinned fruit

Found throughout the eastern states to North Dakota

Can attack sound fruit before they fully ripen

What makes this fruit fly different is the females ovipositor (egg layer), it has teeth to penetrate the skin of fruit

Can vector yeasts and bacteria to the berries

Male: Single spot on wing

2 bands on front legs

ID Characters

Female: a. Enlarged, hardened,

toothed ovipositorb. Clear, sharp and

straight cross vein a

a

bb

Spotted winged Drosophila

• Attack as fruit turn color– Blackberry– Raspberry– Blueberry– Cherry– Strawberry– Grape– Peach

Relative Susceptibility of Fruits

• Most susceptible– Fall raspberries, blackberries

• Very susceptible– Blueberries, black raspberries

• Moderately susceptible– Strawberries (?), grapes (thin skinned),

cherries

• Low susceptibility– Peaches, apples, tomatoes

Traps positive for SWD 2012Traps negative for SWD 2013Traps positive for SWD 2013Reported fruit infestations

Spotted Wing Drosophila Distribution

Fruit Damage Signs

• Early wrinkling and softening seen at 1 to 2 days

• Soft spots and collapse of berry• Small holes created by larvae• Breathing tubes maybe visible with eggs• Oozing berry sap from egg laying holes• Juicy berries• Larvae emerging• Poor shelf life of fruit

SWD Biology

• Most active mid-late summer• Adults live about 3 or more weeks• Females prefer dark, egg laying

concentrated in center of plants• Move to field as fruit begin to ripen

and move out after clean harvest• SWD develops on several common

wild hosts – poke weed, bittersweet, nightshade

SWD Biology• Eggs laid under the skin as fruit ripen• Has breathing tubes to surface• Translucent small (1/4”) larva

(maggot) under skin

What We Learned in 2013

• Too late to affect strawberries, black raspberries and early blueberries!– 2014??

• Traps alerted growers to SWD presence before damage was noted

• SWD widespread throughout KY by end of July• SWD blackberry and raspberry losses severe

across state• SWD controls with insecticides can be

effective for commercial producers applied correctly

What We Learned in 2013

• Grapes, peaches, apples, tomatoes• Apparent increases in other fruit flies

Risk Factors – MSU (R. Isaacs)

• Inter-spray intervals too long• Wooded borders• Dense canopies• Water volume too low• Not reapplying after rain• Using too low rates• Picking intervals too long• Using ineffective products

Monitoring is Critical!

Egg sampling / 20 x hand lens

Larval sampling / sugar water floatation

Adult sampling sugar/yeast traps

Commercial Growers

Monitoring• Examination of susceptible fruit

near harvest for larvae• Baited traps– Bait: Combine 4 Tbsp sugar, 2 Tbsp

yeast, and 2 quart warm water– Use ½ cup bait per trap + 2 drops

dish soap– Trap: Clear 1 liter container with

many small holes below rim– Place in shady, dense part of

canopy– Check weekly– Replace vinegar weekly,

do not dispose of vinegar in field

Commercial Growers

SWD Floatation Method• Can be used to check berries for

eggs & larvae• Mix ½ cup sugar in 1 quart water• Mash suspected berries in plastic bag• Add sugar water and shake• Berries should sink, maggots float

Commercial Growers

Integrated Management (IPM)

• Monitoring plantings/surrounding areas with traps• Reduce alternate host plants in surrounding habitat

if practical• If spotted wing drosophila is NOT found, DO NOT

use SWD insecticides before harvest• If SWD IS found, treat crop on 4 to 7 day intervals

as fruit begin to color through harvest, retreat after rain

• Watch Pre Harvest Intervals (PHI) carefully• Rotate insecticide chemistries for resistance

management• Continue to monitor with traps to determine

effectiveness• Sample fruit for SWD using the fruit-dunk flotation

method• Consider postharvest clean-up spray to reduce

population

Commercial Growers

Spotted winged DrosophilaSWD insecticides (From: Various universities)

• Diazinon 7 day Group 1B• Brigade 7 day Group 3• Danitol 7 day Group 3• Mustang Max 7 day Group 3• Baythroid 7 day Group 3• Delegate 5-7 day Group 5• Malathion 5-7 day Group 1B• Lannate 3 - 5 day Group 1A• Entrust 3 - 5 day Group 5• Pyrethrum 0 – 2 day`Group 3• Sevin < 1 day Group 1A

Watch Pre-harvest intervals (PHIs) carefully when spraying in harvest periods

Commercial Growers

Pre Harvest Intervals on Small Fruit

Insecticide

Effectiveness

Strawberry

Caneberry

Blueberry

Grape

Diazinon 7 NA NA 7 28

Brigade 7 0 3 1 30

Danitol 7 2 3 3 21

Mustang Max

7 NA 1 1 1

Baythroid 7 NA NA NA 3

Delegate 5-7 NA 1 3 7

Malathion 5-7 3 NA NA 7

Entrust 3-5 1 1 3 7

Lannate 3 NA NA 3 1/14*

Pyrethrum

2 0 0 0 0

Sevin 1 7 7 7 7

Commercial Growers

Recommended Insecticides for SWD

Commercial Growers

Getting the Coverage Needed

• Target for the sprays is to kill the adults before egg laying

• Flies hide in the dense part of the canopy until temps drop in late afternoon

• High pressure sprays needed to penetrate dense foliage

• Mist-blower sprayer - $700

Commercial Growers

Rotation of Modes of Action• We know a lot about drosophila

genetics• With most types of resistance, only a

single base-pair substitution is needed.

• We must rotate MOA with each subsequent sprays

• Groups 1B, 3, and 5 are mosteffective

Commercial and Backyard Growers

Recommended Insecticides for SWD

Commercial Growers

Pesticides During Harvest Issues

• Mandatory Pre-Harvest Intervals– Food safety issues

• Overlap of harvest with bloom– Pollinator protection

Commercial and Backyard Growers

Cultural Controls

• Practice Sanitation = Clean harvest – Don’t leave overripe or

damaged fruit in the field

• Harvest and refrigerate immediately

• Post harvest cleanup

Commercial and Backyard Growers

Cultural Controls

• Select early-ripening varieties when replanting

• Prune plants to promote an open canopy

• Reduce wild alternate hosts, if practical

• May be possible to trap out the flies, traps <30’ apart (more research needed)

Commercial and Backyard Growers

Other control measures: Netting <1 mm

In place before fruit ripen

Commercial and Backyard Growers

• May be practical for small plantings– ProTekNet Ultimate Plus (25 gm/m2) – ProtekNet Standard Plus (80 g/m2)– Remay

• Expensive, must be in place before fruit ripen

• Secured at the ground• Also reduces bird damage

Netting for Small Plantings

SWD FactsheetsCommercial Growers

Getting Your Flies Identified

• Send them in to me in Lexington– Provide an email for a response

• Reference samples in alcohol– 2 male, 2 female, 2 larvae SWD– Available at ANR updates for agents– Available for commercial growers

at Fruit and Vegetable Conference

Commercial Growers

Plastic traps available

• jess.cole@uky.edu• Up to 2 per county,

can be reused with subsequent crops through the summer