Cooperative Extension Service

STATUS OF BROAD MITE

MANAGEMENT ON BLACKBERRY

Dr. Donn Johnson dtjohnso@uark.edu

OUTLINE

• Worldwide distribution & Hosts • New hosts in USA • Impact of damage • Mite stages and Life cycle • Overwinter / Seasonal biology / Dispersal • Miticide efficacy • Release predatory mites • High tunnel management • Summary & Future needs

Worldwide Distribution of Broad Mites

• Outside – prefer tropic, sub-tropic

• Greenhouse pest USA - new

detections in fruit plantings in fields and high tunnels

Hosts

1890: on tea in Sri Lanka 1904: on figs and mango plants in New York

Now pest of 60 plant families: • Apple, avocado, blackberry, beans, cantaloupe, citrus, coffee,

cotton, cucumber, eggplant, grapes, guava, lemon, mango, papaya, pear, potato, strawberry, tea, tomato, and watermelon

New Hosts in the USA • 1979: Lemon - coastal California • 2007: Blackberries – Arkansas • 2014: 1st commercial damage to

blackberries in AR • 2018: more Blackberries – China,

S. Africa, Mexico, USA: Illinois, Indiana, Maryland, North Carolina, Oklahoma, Pennsylvania, South Carolina, Virginia, and California – Strawberrry - Florida

What is impact of damage by

broad mites to blackberries?

• Feed on and inject saliva with toxin into expanding terminal and lateral leaves and flower buds/fruit

• Damage - deformation: – Downward and upward leaf curling – Rigidity, shriveling, blistering – Bronzing and less shiny leaves – Death of terminal & lateral leaves and flower/fruit death

Reduced yields of primocane blackberry in field and high tunnels

Goal: To Develop a Broad Mite IPM system for blackberry growers

1st Damage = cupping & bronzing

Healthy –light green shiny leaves

Seasonal Variations in Terminal Leaf Damage

Leaf Death

Upward

Cupping

Downward Cupping

Mid-season Damage & Death of Leaves

Fire blight-like symptoms

Healthy lateral

Down cupped leaves

Dead laterals

Dead leaves

Mite Stages • Look on underside of expanding terminal/lateral leaves and fruit buds/fruit • Stages – use 30x-60x jewelers LED hand lens or stereomicroscope:

Egg – 0.1 mm, clear, oval, 30 white spots

Larva – 0.14 mm, 6 legs, off-white, oval, white stripe (back)

Nymph – 0.12 mm, 8 legs, clear, elliptical, white hourglass mark

Male – 0.14 mm, 8 legs, clear, oval, white rectangle mark

Female - 0.14 mm, 8 legs, amber, oval, white hourglass mark

Life Cycle

• Spotted egg adult = 4-5 days – 112 degree-days at 50°F (10°C) – Die above 91° F (33°C)

• Male carries immature female nymph & disperse to new leaf/plant to mate

• Lay 25 eggs over 5 days on underside of expanding leaves

• Live 11-15 days

MALE

NYMPH

EGG

Some photos: okstate.edu & Gil Luypaert (2015)

LARVA

FEMALE

Video: female & male broad mites walking on underside of blackberry leaf

Develop terminal leaf sampling method and mite threshold for damage

Sampling for Broad Mites & Predatory Mites Collect ten, 2nd expanded terminal leaflets

Count # mites on underside of each leaflet by scanning each ¼” square of screen Calculate average/leaflet

Broad Mites, Damage Threshold and Predatory Mites per Primocane Leaflet (Searcy, AR 2015)

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Cupped/bronzed leaves appear

Bloom

Proposed Damage Threshold = 5 broad mites per leaflet

Determine seasonal phenology and distribution within field or high tunnel using floatation sampling

High tunnel Field

Leaves Cane Soil or Leaf Litter

Materials and Methods Experimental Design

• Light dries soil & leaf litter - mites & debris fall down funnel into vial • Centrifuge vial & remove mites & debris • Use sugar-water floatation and sieve to separate mites from debris • Count mites per sample using stereomicroscope

Floatation Method:

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Overwinter in Leaf Litter

If > 10°C (50°F) mites develop

Dispe rsal = spread Hope, AR

Spring Mite Buildup on

Leaves & Soil Litter

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Overwinter In

Leaf Litter

Mite dispersal

Clumped

Spread Damage

How Broad Mites Spread?

• Field

– Wind carries mites to far-away plants – Males carry females by walking to adjacent plants – Human activity:

• Plant infested plants & contact between plants • Primocane tipping & summer floricane cane removal • Harvesting fruit • Farm tools – air blast sprayers, weed trimmers, etc.

• Greenhouse

– Fans blow mites – Adult females attach to white flies and spread

Spread of

Broad Mites

in 2017

(Judsonia,

AR)

Big drop in broad mite numbers by 13 March (winter kill)

High broad mite numbers enter winter

Broad mite buildup in a plot by 30 May Mites in all plots by 12 June

Damage appears

5 replicates each Infested leaves dipped 5 sec in: • Agri-Mek 3.5 fl oz/acre • M-pede 1 or 2% • MicroThiol 10 or 15 lbs/acre • JMS Stylet Oil 1 or 2% • Trilogy 1 or 2% • Quillaja 2 or 4% • Penetrate W.N.G. 2 or 4% • Zeal • Movento

Miticide Bioassay

Cooperative Extension Service

Results: 2016 Miticide Efficacy (Lab)

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Trials 1 and 2 petri dish bioassay: % broad mite mortality 24 and 72 hrs after treatment

Potential miticides > 85% Effective: Agri-Mek + NIS

(has EPA label) MPede 2% Microthiol 15 lbs JMS Stylet Oil 2% Trilogy 1%

Field Trials of Predatory Mites and/or Sulfur sprays

If established mite population, sprinkle bran with high dose of predatory mites to treat

Preventatively, attach sachets of mites that slowly emerge over

several weeks

N. swirskii

Materials and Methods: Predatory Mite Field Trials (Released May 20)

Amblyseius

swirskii N. californicus Neoseiulus

cucumeris N. andersoni

Results: A. andersoni, N. californicus, N. swirskii,

reduced broad mites a short time, but not N. cucumeris

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Hilltop Plots in Clarksville AR

N. andersonii N. californicus Control N. cucumeris N. swirskii

B

Plastic covers untreated

control plots to keep sulfur

off during sulfur spray

2016 Field Efficacy: Spring Sulfur Miticide &/or Predator Mite Releases

Field Efficacy: Spring Sulfur Miticide &/or Predator Mite Releases

(2016 Searcy, AR)

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Releases

Sulfur sprays

Agri-MekReleases

Primocane Fruiting Blackberries in High Tunnel

June 26

Microthiol 15 lb/acre

Sulfur w/ or w/o Predatory Mites Delayed Broad Mite Increase

in High Tunnel (2016, Hope, AR)

Summary: • Developed sampling methods for terminal leaves, soil and litter • Most broad mites die during winter, but a few survive in leaf litter • In May, broad mites infest and damage a few plants, but by mid-June

spread and cause damage throughout planting • Tentative treatment threshold is 5 mites per leaflet or 1st damage • Predatory mites, A. andersoni, N. californicus, N. swirskii, reduced

broad mites a short time • Foliar sprays of Sulfur and releases of predatory mites reduced broad

mite densities and delayed buildup

Summary:

Cooperative Extension Service

Summary:

Miticides: Agri-Mek SC + NIS, M-pede, Microthiol (Sulfur), JMS Stylet Oil, Trilogy killed > 80% of broad mites • Best summer treatment is Agri-Mek SC + NIS • If < 90°F, Microthiol, M-Pede, JMS Stylet Oil provided 2-week

knockdown of broad mites

• By late-May, begin weekly scouting of blackberry field • Look for first terminal leaf bronzing and/or cupping • Check underside of expanding leaflet from 2nd leaf down from terminal

for broad mites (30X hand lens) • If damaged and broad mites are present:

– Rogue out infested plant and adjacent plants – Apply miticide if several plants have broad mites and damage,

before first berries begin to ripen on floricanes • Reapply miticide only if/when you detect new mite-infested terminal

leaf damage

Broad Mite Management

Summary of Future Studies: • How to determine if purchased blackberry plants are free of broad

mites? • Does winter removal of understory leaf litter delay or minimize or

delay spring buildup of broad mites? • Determine how broad mites redistribute across a blackberry

planting: human activity, aerial dispersal and/or phoresy? • What are the most effective miticides and time to apply each

against broad mites? • What predatory mite species, release rate and timing biologically

control broad mites and in what climates? • Are there strains of fungi (like Bt) that control broad mites?

Summary of Future Studies:

Funding:

USDA National Institute of Food and Agriculture, Hatch project 223689 USDA/SARE LS12250 Southern Region Small Fruit Consortium/ IR-4 Program 2015-06 / 2016 R-07 Specialty Crop Block Grant / Arkansas Ag. Dept. and Extension IPM North American Raspberry & Blackberry Association (invited conference speaker) DPI GLOBAL

Technical assistance: Dr. John Clark, Jessica LeFors, Dr. Justin Renkema, Dr. Elena Garcia, Dr. Terry Kirkpatrick, Dr. Jimmy Klick, Dr. Mike Rinker, Kathy Demchak, Barbara Lewis, Luke Freeman, Taunya Ernst, Jeff Inness, Sherri Sanders, Tammi Woodruff, Margie Miller, Katie Sullivan, JD Barnham and Cathy Howard, Arkansas Berry Growers

ACKNOWLEDGEMENTS

Questions?

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• 2018 label for broad mites on caneberries

• Restricted use pesticide • Ingredient: Abamectin • PHI: 7 days; REI: 12 hr • Rate: 3.5 fl oz/A + NIS

Adjuvant Required: mixed with a nonionic surfactant (0.1-0.5% NIS v/v) • Application Interval: Wait at least 7 days before repeating application • Do not make more than 2 sequential applications of Agri-Mek SC • Maximum Amount per Year: 10.25 fl oz/A