Degree days for root, bulb and leafy vegetable pests – 11 July 2011

Bradford/Holland Marsh, Sarnia, and London areas have reached the degree day threshold for emergence of the 2nd generation of onion maggot. Degree days have accumulated in London and Sarnia areas indicating emergence of the 2nd generation of cabbage maggot. The Windsor area will reach the degree day threshold for emergence of the 2nd generation of carrot rust fly in the next few days. In the Wellington area, degree days have accumulated reaching the threshold indicating local emergence of adult aster leafhopper.

Here are the degree days accumulated from April 1st until July 11th, 2011.

Area

Onion Maggot

Cabbage Maggot

Carrot Rust Fly

Carrot Weevil

Bradford/Holland Marsh*

1034.9

N/A

1131.7

769.4

Sarnia

1013.1

840.3

1106.7

760.1

London

1059.6

880.5

1153.7

794.2

Wellington

897.4

725.3

987.2

642.4

Windsor

1227.7

1038.2

1326.7

950.8

Area

Tarnished Plant Bug

Leafhopper

GDD

Bradford/Holland Marsh*

402.9

608.9

941.6

Sarnia

408.3

608.1

924.6

London

414.7

630.7

968.8

Wellington

298.6

490

810.1

Windsor

560.8

785.7

1130.4

* Data provided thanks to Muck Crops Research Station, Department of Plant Agriculture, University of Guelph

 Degree day 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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