Degree days for root, bulb, and leafy vegetable pests

Marion Paibomesai, Vegetable Crop Specialist, OMAFRA

Here are the degree days accumulated from April 1st until May 12th –15th, 2011.

Area

Onion Maggot Cabbage Maggot Carrot Rust Fly

GDD

As of

Bradford/ Holland Marsh* 166.6 N/A 203.4 133.3 13/05/2011
Sarnia 177.3 124.5 210.9 148.8 12/05/2011
London 233.1 168.0 270.2 199.3 15/05/2011
Wellington 169.4 111.3 202.2 139.1 15/05/2011
Windsor 274.0 198.5 316.0 225.3 15/05/2011

Area

Carrot Weevil

Tarnished Plant Bug

Leafhopper

GDD

As of

Bradford/ Holland Marsh* 81.2 10.3 40.9 133.3 13/05/2011
Sarnia 91.3 30.6 68.2 148.8 12/05/2011
London 138.7 37.7 87.4 199.3 15/05/2011
Wellington 84.9 13.0 44.5 139.1 15/05/2011
Windsor 168.1 54.9 115.2 225.3 15/05/2011

* 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 128 390 n/a

Enough degree days have accumulated indicating the emergence of 1st generation adults of onion maggot and the beginning of egg-laying for carrot weevil in the London and Windsor areas. Also in the Windsor area, the emergence of overwintering carrot rust fly adults and the hatching of overwintering aster leafhopper eggs is soon approaching. Still awaiting enough accumulations in the other areas.

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