Overview of Insect Managementin Carrots

Overview of Insect Managementin Carrots

Brian A. NaultBrian A. NaultDepartment of EntomologyCornell UniversityNew York State Agricultural Experiment StationGeneva, NY 14456

Department of EntomologyCornell UniversityNew York State Agricultural Experiment StationGeneva, NY 14456

February 10, 2004February 10, 2004

Pearl CreekPearl Creek MorganvilleMorganville

Carrot fields in Western New York - 2003Carrot fields in Western New York - 2003

Pearl CreekPearl Creek

MaggotMaggot

Maggots, beetle larvae and disease

Pearl CreekPearl Creek

Feeding injuryby cutworm, grub or mouse?

Feeding injuryby cutworm, grub or mouse?

MorganvilleMorganvillePhysiological cracking and disease?Physiological cracking and disease?

MorganvilleMorganville

Feeding injury by wireworm or grub?Feeding injury by

wireworm or grub? Pythium sp.

QuestionsQuestions

! Was carrot weevil and/or carrot rustfly infesting the carrots?

! Did earlier damage by carrot weeviland/or carrot rust permit secondarypests and pathogens to establish?

Carrot Weevil, Listronotus oregonensisCarrot Weevil, Listronotus oregonensis

!Adults overwinter in or near carrot fields

!Colonize fields in mid-May – late June, often along field edges

!Eggs laid in petioles or crown

!Oviposition scars about 1 mm

!Larva tunnels in root

!Another generation in late August

AdultAdult

ScarScar

LarvaLarva

Torres et al.

Torres et al.

Grafius

Carrot Weevil DamageCarrot Weevil Damage

Managing Carrot Weevil in CarrotManaging Carrot Weevil in Carrot

! Crop rotation (> 1 mile)

! Sanitation (destroy crop residue after harvest)

! Insecticides- Baythroid 2 (2.8 fl oz/acre)- Asana XL (9.6 fl oz/acre)

Scouting for Carrot Weevil in CarrotScouting for Carrot Weevil in Carrot

1) Trap for adults

2) Monitor carrot pieces for scars

Action threshold is> 25% of root pieces withpunctures

3) Monitor plants for oviposition scars/punctures

Action threshold is > 1% infested plants

Stevenson and Chaput

Simonet

Carrot Rust Fly, Psila rosae

!Adults overwinter near carrot fields

!Colonize fields in mid-May – late June

!Eggs laid on ground at base of plants

!Larva tunnels in root

!Two to three generations per year

Stevenson and Chaput

Stevenson and Chaput

Carrot Rust Fly Damage

Stevenson and Chaput

Managing Carrot Rust Fly in CarrotManaging Carrot Rust Fly in Carrot

! Crop rotation (> 1 mile)

! Select fields not sheltered by trees

! Sanitation (destroy crop residue after harvest)

! Insecticide- D.z.n. diazinon (4 lb or 1.5 oz/1,000 sq ft)

Scouting for Carrot Rust Fly in CarrotScouting for Carrot Rust Fly in Carrot

1) Trap for adults- place along fieldedges

- place next to woods

Stevenson and Chaput

Aster Leafhopper, Macrosteles quadrilineatus

!Overwinter as eggs in grain cropsor migrate from southern US

!Eggs hatch in early May

!Adults migrate into carrot fieldsin early May

!Two to five generations per year

Aster YellowsAster Yellows! Adults transmit a phytoplasma

that causes aster yellows

! Adult must feed for a prolongedperiod to acquire phytoplasma

! Phytoplasma must circulate andreplicate for 18 to 20 d before adult becomes infective

! Adult must feed for a prolonged period to successfully transmit

! Three weeks for symptoms toappear

Managing Aster Leafhopper in CarrotManaging Aster Leafhopper in Carrot

! Resistant varieties

! Insecticides- Baythroid 2 (2.8 fl oz/acre)- Asana XL (9.6 fl oz/acre)

Scouting for Aster Leafhopper in CarrotScouting for Aster Leafhopper in Carrot1) Sweep for adults

2) Aster yellows index threshold = percentage of infected adults x leafhoppers per 100 sweeps

50 for susceptible varieties (e.g., 5% x 10 hoppers)75 for intermediate varieties100 for resistant varieties

Note: Conservative estimate is 5% infected adults, but >20% infected can occur. PCR now being used to estimate % infected adults.

3) No spray 3 weeks before harvest, because symptoms take 3 weeks to develop