Degree days for root, bulb and leafy vegetable pests – 25 July 2011

The Wellington area has reached the degree day thresholds for the emergence of 2nd generation onion maggot and cabbage maggot. In the Windsor area, degree day accumulations will reach the threshold indicating emergence of 3rd generation of cabbage maggot in the next 5-6 days. Bradford/Holland Marsh, Sarnia, London and Windsor areas have reached the threshold indicating emergence of the 2nd generation of carrot rust fly.

Here are the degree days accumulated from April 1st until July 25th, 2011.

Area

Onion Maggot(base 4)

Cabbage Maggot(base 6)

Carrot Rust Fly (base 3)

Carrot Weevil (base 7)

Bradford/Holland Marsh*

1314.7

N/A

1425.5

N/A

Sarnia

1294.5

1093.7

1402.1

999.5

London

1345.7

1138.6

1453.8

1038.3

Wellington

1156.3

956.2

1260.1

859.3

Windsor

1545

1327.5

1658

1226.1

Area

Tarnished Plant Bug (base 12)

Leafhopper (base 9)

GDD (base 5)

Bradford/Holland Marsh*

570.7

818.7

1207.4

Sarnia

577.7

819.5

1192

London

588.8

846.8

1240.9

Wellington

445.5

678.9

1055

Windsor

766.1

1033

1433.7

* 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

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