Degree days for root, bulb and leafy vegetable pests – 5 June 2012

Thresholds for onion maggot fly emergence have been reached for all areas. First generation adults of cabbage maggot are expected in all areas. In some areas, LondonWindsor and Thedford, the cabbage maggot adults are probably past peak flights based on degree days. If resident populations are present, carrot rust fly adults have begun to emerge in all areas. If resident populations are present, carrot weevil have likely started to lay eggs in all areas. In the Windsor area, the degree days indicate 90% oviposition by carrot weevil. Based on degree days, tarnished plant bug should have started to emerge in all areas. Overwintering leafhopper eggs have likely started to hatch in all areas. In the Windsor area, emergence of local adult leafhoppers is expected over the next couple days.

Here are the degree days accumulated from April 1st until June 5th, 2012.

(These values are provided as guidelines only. Local environments, soil type, field history, etc. may influence activity of these pests.)

Area

Onion Maggot

Cabbage Maggot

Carrot Rust Fly

Carrot Weevil

As of

Bradford/Holland Marsh*

476.6

n/a

538.2

333.5

04/06/2012

London

513.6

397.1

577.4

348.9

05/06/2012

Wellington

427.1

331.6

482.6

290.3

05/06/2012

Windsor

664.5

536.6

730.4

476.4

05/06/2012

Thedford

505.2

394.7

567.8

345.2

05/06/2012

Delhi

495.3

385.5

559.4

341.2

05/06/2012

Ridgetown

Data not updated since 28 May 2012

Area

Tarnished Plant Bug

Leafhopper

GDD

As of

Bradford/Holland Marsh*

126.5

212.2

356.4

04/06/2012

London

140.4

230.8

389.8

05/06/2012

Wellington

105.3

189.0

324.6

05/06/2012

Windsor

205.7

317.2

520.3

05/06/2012

Thedford

132.4

222.6

381.4

05/06/2012

Delhi

133.3

222.5

370.2

05/06/2012

Degree day model information for pests 

Degree Days

1st Generation

2nd Generation

3rd Generation

Onion Maggot

210

1025

1772

Cabbage Maggot

314-398

847-960

1446-1604

Carrot Rust Fly

329 – 395

1399-1711

n/a

Carrot Weevil

138 – 156
455 (90% oviposition)

No model available

n/a

Tarnished Plant Bug

40

n/a

n/a

Aster Leafhopper

128 (overwintering egg hatch)

390 (local adult emergence)

n/a

n/a


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