Root, bulb, leafy and brassica vegetable pest report – 29 May 2013

See below for the degree days accumulated from April 1st until May 29th, 2013. These values are provided as guidelines only and provide an estimate of activity and development stages of certain insect pests in the field.  Local environment/climate/conditions, soil type, field history, etc. are likely to influence activity and presence of these pests in the field. 

Thresholds for emergence of first generation onion maggot fly adults have been reached in all areas for which degree days are calculated for. The Muck Crops Research Station indicated peak flight of onion maggot a week ago with counts decreasing early this week (as of 27 May 2013). The Muck Crops Research Station noted today (30 May 2013) that onion maggot flies counts have increased since early this week. First generation cabbage maggot adults have likely emerged in Windsor, London and Ridgetown areas and are likely to emerge over the next few days in Thedford and Delhi areas. For all areas, accumulated degree days indicate emergence of carrot rust fly adults, if resident populations are present. Carrot rust flies have not been caught on traps at the Muck Crops Research Station in the Holland Marsh (as of 30 May 2013). If resident populations are present, carrot weevil have likely started to lay eggs in all areas as indicated by accumulated degree days. Tarnished plant bugs have likely emerged in all areas; however, the Muck Crops Research Station scouts have not seen tarnished plant bugs on celery in the Holland Marsh yet (as of 30 May 2013). Overwintering leafhopper eggs have likely started to hatch in all areas.

Area

Onion Maggot (base 4)

Cabbage Maggot (base 6)

Carrot Rust Fly (base 3)

Carrot Weevil (base 7)

As of

Bradford/Holland Marsh*

389.3

n/a

438.6

259.1

29/05/2013

London

396

306.7

444.3

268.5

29/05/2013

Wellington

334.7

253.6

380.6

217.9

29/05/2013

Windsor

483.3

385.9

535.9

341.2

29/05/2013

Thedford

377.1

291.6

425.2

256.6

28/05/2013

Delhi

373.9

287.1

422.4

248.3

29/05/2013

Ridgetown

389.5

302.7

438.2

262.3

29/05/2013

Area

Tarnished Plant Bug (base 12)

Leafhopper (base 9)

GDD (base 5)

As of

Bradford/Holland Marsh*

106.2

189.3

343.7

29/05/2013

London

115.3

199.8

349.8

29/05/2013

Wellington

79.0

153.9

291.8

29/05/2013

Windsor

161.2

260.6

433.3

29/05/2013

Thedford

110.4

191.2

331.8

28/05/2013

Delhi

94.1

177.2

328.6

29/05/2013

Ridgetown

115.3

195.2

344.5

29/05/2013

Data provided by Environment Canada.

*Data provided by Muck Crops Research Station, University of Guelph.

Degree day model information for pests 

Thresholds

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 (first egg-laying)
455 (90% of eggs laid)

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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