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6/26/2017
1
Potato Leafhopper Management
Lily Calderwood, Ph.D.Cornell Cooperative ExtensionCapital Area Agriculture & Horticulture [email protected]
Potato leafhopper (PLH)Empoasca fabae
HopperburnNymphs
Adult + nymph
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Potato Leafhopper Life History
• Economically damaging pest of alfalfa, potato, soybean, raspberry, maple
• Feeds on >200 broad leaf plants
• Prefers to feed on new growth
• Piercing‐sucking mouthparts phloem feeders
• Documented as a pest on hops in 1800s (Magie 1942)
• 2‐3 generations/season
• Has killed first year hop plants in Northeast
• Yearly population variation
Yearly Population Variation
Overwinter
Spring Migration
Alburgh, VT
• 2012: Late June peak
• 2013: June‐July steady
• 2014: Low pop, late arrival
• 2015: Late June peak
• 2016: High pop, late June peak
Calderwood et al. 2015
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1st Instar Nymphs
Second Generation6/23/17
Severe Hopperburn
No Hopperburn
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Hopperburn
Visual damage doesn’t show up until ~ 5 days after feeding occurs.
Control Option
• Spray pyrethroid insecticide
– Significantly reduce PLH population
– Risk two‐spotted spider mite outbreak
• As of 2017, there is no PLH Economic Threshold.
• Current recommendation to shake plants. If PLH adults fly out, you need to spray.
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Yes, you can try releasing biocontrols…
Lady bugs can fly away.
‐Squirt them with water‐Keep in fridge‐Release in the evening
Research into Alternatives
1. Trap Cropping
2. Plant Defense
(physical and chemical)
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Management in Other Crops2. Plant defense. Resistant alfalfa varieties have very hairy leaves.
1. Intercropped soybean with w. wheat.PLH is not attracted to these fields.
Resistant alfalfa
Susceptible alfalfa
Miklasiewicz and Hammond 2001 Elden and McCaslin 1997
In years with high PLH population and well established clover stand PLH preferred red clover over hops.
> >
Clover stand(10 x 30 ft)
Hop plants Diverse mix (Polyculture)
Calderwood et al. 2017
1. Trap CroppingFlowering Ground Cover Study
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Mono vs. Polyculture Alfalfa
Lamp et al. 1984, Oloumi‐Sadeghi et al. 1987, Lamp 1991, and Straub et al. 2013
Preferred by PLH
Alfalfa Monoculture Alfalfa Polyculture
Trap Crop Management
• How big does a legume stand need to be?
• How far into the hop yard does the alfalfa pull PLH away?
• Do the leafhoppers need to be removed from the trap crop at a certain density?
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2016‐2017 SARE Farmer Grant
Alfalfa trap crop plots are 4000 ft2
Sticky card placed in trap crop trts and throughout hop yard
4 replicates
Control ‐mowed
Alfalfa –Spray at ET
Alfalfa – No Spray
20 + acre potato field!
July 1 (Average Peak PLH population)
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N
Yard B, 2016 Mean PLH/trap. Excluding July 1.
POT A TO
P O T A T O
N
Yard B, mean whole season PLH/trap including July 1.
POT A TO
P O T A T O
June 20 mean 4 PLH/trapJuly 1 mean 75 PLH/trap
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Surrounding Habitat Influences PLH
Farm B: Surrounded by hay fields + meadow
Farm C: On top of a hill, very windysurrounded by diverse meadow
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2. Plant Defense
2012 and 2013 Mean # PLH/leaf in Alburgh, VT
Have you noticed that PLH prefer some cultivars over others?
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Liberty Centennial
Bulbous Trichome
Peltate Trichome= Lupulin Gland
Hop Plant Defenses and Potato Leafhopper
Less leafhoppersMore lupulin glands on leaves
More leafhoppersLess lupulin glands on leaves
Sid Bosworth
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Currently in search of the “Hairiest Hop”
Hop Looper Caterpillar
6/22/2017
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Cornell Cooperative ExtensionCapital Area Agriculture & Horticulture Program
Thank you!