Joanne Whalen

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Forage Insect Pest Review
Joanne Whalen Extension IPM Specialist University
of Delaware Jan 8 and 9, 2008
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Crops and Insect Pests

• Alfalfa alfalfa weevil and potato leafhopper
• Timothy Cereal Rust Mite
• Orchardgrass Billbugs
• New Labels for Grass Forage, Fodder and Hay Group
  and Grasses Grown for Seed and Pastures and
  Rangeland

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Things to Remember

• Weevil injury occurs primarily on the first crop.
• Yield impact from weevil feeding declines as
  alfalfa height increases
• Focus scouting effort on larval activity in
  alfalfa 12 or less in height.
• Once alfalfa reaches 16 or more in height,
  early cutting is the preferred option.
• During periods of heavy weevil activity, early
  growth of the second cutting may be impacted.

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Alternative/Biological Controls

• Three beneficial wasp species attack the larvae
• Fungal Pathogen attacks larvae turn brown and
  attach to foliage

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Chemical Controls

• Imidan and Lorsban (organophosphates)
• Baythroid, Mustang MAX, permethrin, Proaxis,
  Warrior ( pyrethroids)
• Warrior and Mustang Max labels now include forage
  grasses so can now be used on mixed grass/alfalfa
  stands (new in 2007)
• Steward

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Things to Remember

• Generally considered a migratory pest here by
  April
• Usually infests the second crop but sometimes
  does not reach economic levels until the third
  crop
• Cool night temperatures or excessively high
  temperatures gt 95 degrees retard development
  times.
• Activity usually peaks in July and declines in
  mid August.
• Heavy infestations can stunt growth, especially
  new stands and regrowth following harvest.
• Excessive feeding reduces yield of both current
  and subsequent crops.

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Alternative Controls

• Fungal Pathogens
• Early Cutting
• Resistant Varieties Presence of glandular hairs
  reduced survival of adults and nymphs feeding on
  the foliage, and impedes egg laying and feeding
  preference of adults.

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Chemical Controls

• Same pyrethroids as for weevil
• Dimethoate( organophophate)

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Cereal Rust Mite
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Feeding sites

• Use piercing-sucking mouthparts to feed
  exclusively on thin-walled special cells at the
  base of leaf grooves. Infested leaves curl and
  eventually show a rusting appearance.
• Prolonged feeding results in retarded growth,
  stunting, and discoloration.
• Can reduce yields by 50
• Reduces hay quality

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Things to Remember

• Mites quickly infest new plantings by wind
  dispersal of immatures. Other grasses (esp. tall
  fescues) harbor low populations and may serve as
  reservoirs for infestation.
• Cold-adapted - develops gradually in the fall
  and increasingly active throughout the winter.
• Adult mites feed on the youngest tissues in the
  plant crown
• Egg-laying begins in January and peaks in early
  March.
• Immatures are found higher in the canopy as
  leaves unfold in the new growth.
• Generation time is 21-28 days at spring
  temperatures - many generations per year.
• Mite levels (gt1000/leaf) and feeding damage peak
  in late April-early May.

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Alternative Controls

• Hot,dry conditions and sub-freezing temperatures
  for prolonged periods reduce mite survival.
• Host plant resistance holds the greatest promise
  for long-term, sustainable management.
• At present, all timothy varieties grown are
  susceptible. Grow an alternative grass species
  that is less susceptible (e.g. reed canary
  grass).
• Late fall cutting removes mite stages and reduces
  the available food and shelter for mites to
  develop during the winter and early spring

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Chemical Control

• Only material available under a Section 24C label
  ( special local needs label must have label in
  your possesion) Sevin XLR PLUS at 3 pts. per
  acre (1.5 pounds ai per acre) checked on it
  with DE ?? MD
• Must be applied with ground equipment with
  adequate water for complete coverage (20 or more
  gallons by ground).
• Apply at 3-4 weeks after green-up in the spring
  do not apply within 30 days of harvest.
• Treat fields with a previous history of CRM
  and/or when 25 of the plant tillers exhibit
  curled tips within several weeks following
  green-up.
• One application usually reduces mite
  infestations enough to allow normal growth of
  timothy.

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Orchardgrass Delayed green-up, Die off Caused
by aphids, grubs, billbugs.
Reasons for recent pest problems mild winters,
dry fall and winter followed by summer drought
(plant stress).
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GREENBUG
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Green June Beetle
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Management Options

• Greenbugs malathion will only suppress and only
  labeled for grass pastures and rangeland grasses
  Warrior (new grass hay label in 2007) has
  greenbug on label but must be applied early
  before leaves rolled
• No Chemical controls for grubs till and replant

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• Billbugs -- orchardgrass, Kentucky bluegrass,
  zoysiagrass, bermuda grass, perennial ryegrass,
  fescues, and timothy.

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Management Options

• Adult control offers the best option.
• Look for paired feeding holes of adults in late
  fall and again in the early spring. Amount of
  damage determines need to control adults in
  spring before eggs are laid.
• Sevin XLR only labeled for pastures and grasses
  grown for seed have evaluated in trials in VA
• New Warrior Label in 2007- has billbug
  suppression only
• Timing is important monitor adults in spring
  looking for presence of paired-leaf feeding
  holes degree-day accumulations presence of
  adults in pitfall traps

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Review of New Labels in 2007

• Mustang Max and Warrior now Labeled for Grass
  Forage, Fodder and Hay Group and Grasses Grown
  for Seed and Pastures and Rangeland (includes
  timothy and orchard grass)
• Insects on Labels
• - Mustang Max weevils, leafhoppers, some aphids
  but not greenbugs (control will vary with
  species), grasshoppers, some worms billbugs not
  on label
• - Warrior number of worm species, grasshoppers,
  billbug (suppression only) greenbugs ( must
  apply before leaves rolled by insect feeding)

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Questions ?