Insect Management in Pumpkins

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Insect Management in Pumpkins

• Celeste Welty
• Ohio State University
• February 2002

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Pumpkin Pests

• Cucumber beetles
• Aphids
• Two-spotted spider mite
• Squash bug
• Squash vine borer

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Cucumberbeetles

• Important damage (adults)
• Chew seedlings
• Transmit bacterial wilt
• Chew on fruit surface
• Less critical damage
• Larvae chew on roots
• Adults chew on flowers

4
Bacterial wilt of cucurbits

• Vectored by cucumber beetles
• Transmitted in feces
• Enters via wound in plant, such as feeding wound
• Hosts
• Well-known killer of cukes melons
• Recently adapted to kill squash pumpkins but
  slower to kill

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Bacterial wilt on pumpkins

• Study in Indiana (G. Brust 1997)
• Plant susceptibility
• most at cotyledon stage
• slightly at 1-leaf, 2-leaf stages
• Howden more susceptible than 14 other varieties

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Bacterial wilt of cucurbits

• Beetle species common in cucurbits
• Known vectors
• Striped cucumber beetle
• Spotted cucumber beetle
• Not known to vector
• Western corn rootworm beetle
• Northern corn rootworm beetle
• Pale-striped flea beetle

striped
spotted
western
pale-striped
northern
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Cucumber beetle management on seedling pumpkins

• Soil systemic insecticide, at-plant
• Furadan 4F
• Admire 2F
• (Platinum 2SC)
• Scout for beetles to 4-leaf stage
• Thresholds, beetles per plant
• 0.5 beetle at cotyledon 1-leaf stage
• 1 beetle at 2-leaf to 4-leaf stage
• 3 beetles at gt4-leaf stage

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Admire 2F on pumpkins

• Label rate 16 - 24 fl. oz. per acre
  (74 - 110/A)
• row spacing Rate (fl. oz.) /1000 ft.
• 8 ft 2.9 - 4.4
• 6 ft 2.2 - 3.3
• 4 ft 1.5 - 2.2
• 3 ft 1.1 - 1.7

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Cucumber beetle management on maturing pumpkins

• Scout for beetle damage
• Examine 50 fruit
• Feeding usually starts
  on handle
• Threshold (tentative)
• 20 of fruit with scars
• Insecticide
• pyrethroids (Asana, Pounce, Danitol, Capture)
• Sevin XLR or 80S
• Thiodan
• do not spray when flowers open

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Aphids
winged aphid
wingless aphids colonizing leaf
fly, land, taste bring in virus often do
not colonize
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Watermelon Mosaic Virus
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Aphids VirusesSeasonal Occurrence in Ohio

• Winged aphids
• Daily arrivals June - September
• Usually a surge in late July
• Watermelon mosaic virus
• First detection last week July to first week
  August
• Consistent over many locations many years

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Vector tests for watermelon mosaic virus on
pumpkins

• Species of plants infected
• 1997 1998
• (individual (group
• tests) tests)
• green peach aphid 22 -
• melon aphid 21 -
• potato aphid 2 18
• artichoke aphid 0 6
• corn leaf aphid 0 0

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Reservoirs of Watermelon Mosaic Virus

• Among 47 plant species tested
• Most common
• Virginia pepperweed
• shepherds purse
• Occasional
• dandelion
• field bindweed
• purple (red) deadnettle
• goldenrod

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Insecticides for Aphid Virus Management

• Effective?
• Aphid control yes
• Primary virus infection no
• Secondary virus spread
• if primary infection widespread no
• if primary infection not widespread maybe

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Management of Aphids WMV on Pumpkin

• Strategies tested, 1994-1998
• Stylet oil
• Row covers
• Reflective mulch
• Soil-applied systemic insecticides
• Foliar insecticides
• All strategies helped control aphids but none
  affected virus

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Aphid Virus Management on Pumpkins

• Best hope is resistant varieties

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Spider Mites

• Tolerable at low density
• Suppressed by natural predators
• Flare up in hot dry weather
• Chemical control
• Dimethoate
• Agri-Mek
• Danitol, Capture
• Kelthane
• (Metasystox-R)

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Squash Bug

• Damage
• Suck sap from leaves, stems
• Patches of tissue turn black, die
• Plants wilt
• Young plants can die
• Plants can live but not develop fruit
• Bugs feed on fruit before harvest

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Squash Bug

• Life Cycle
• Overwinters as adults
• Adults emerge mate in June
• Adults lay eggs on leaf underside
• Eggs hatch 1 - 2 weeks
• Nymphs feed in daytime for 1 month
• One generation per year

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Squash Bug

• Cultural control
• Rotate with non-curcurbit crops
• Promote early growth of crop
• Destroy crop remains

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Squash Bug

• Biological control
• Parasitic fly
• Trichopoda pennipes
• lays egg on large nymph or adult bug
• common in Ohio
• Parasitic wasps (egg parasitoids)
• Ooencyrtus anasae
• Gyron pennsylvanicum
• found occasionally in Ohio

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Squash Bug

• Chemical control
• Nymphs more susceptible than adults
• Hard to contact in canopy
• Need good spray pressure
• Insecticides
• Ambush, Asana, Capture, Danitol, Pounce
  good
• Thiodan fair
• Sevin poor

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Squash Vine Borer Life Stages
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Squash Vine Borer Chemical Control

• Timing
• 2 sprays, 1 week apart
• At time of peak egg hatch
• Estimate by catch of moths in pheromone trap
• Peak usually early July
• Products pyrethroid or Thiodan
• Direct spray at base of plants

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Squash vine borer trapping

• pheromone lure available for adult males
• controversy 1
• doesnt work
• not true if placed low, in canopy
• controversy 2
• works too well
• study in N. Carolina 1991
• plots with vs without lures
• 5 lures _at_ 4 large plots
• damage higher in plots with lures
• conclusion
• trap helpful with timing insecticide
• use only 1 or 2 traps per field

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Squash vine borer moths in pheromone
trap Columbus 1999
100
l
80
l
60
Number of moths per week
l
40
l
l
l
20
l
l
l
l
l
0
7/6/99
8/3/99
7/13/99
8/24/99
8/10/99
8/17/99
6/15/99
6/22/99
6/29/99
7/20/99
7/27/99
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Squash vine borer trap

• trap
• plastic funnel trap or bucket trap
• Unitrap (standard yellow/white) _at_ 8.95
• lure
• change every 4 weeks
• 1.65 each
• fumigant strip
• use 1 fumigant strip per trap
• replace every 4-6 weeks
• 1.50 for one large strip
• 5.65/bag of 25 small strips
• Place close to ground
• from Great Lakes IPM, Vestaburg Michigan

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Happy Halloween!