Root, bulb, leafy and brassica vegetable pest report – 8 July 2013

See below for the degree days accumulated from April 1st until July 8th, 2013.These values are provided as guidelines only. Local environments, soil type, field history, etc. are likely to influence activity of these pests.

Second generation of onion maggot flies have likely started to emerge in the Windsor area and are likely to emerge over the next couple days in the London, Ridgetown, Thedford and Bradford/Holland Marsh areas. According the Muck Crops Research Station report, onion maggot fly activity around the Holland Marsh is moderate. Onion thrips have been seen on onions in the Holland Marsh and some areas in Southwestern Ontario. Be sure to scout for thrips. No onion downy mildew has been reported; however, in the Holland Marsh, the risk of downy mildew on transplanted onions is moderate to high. Risk is low to moderate on seeded onions at this time. The risk of Botrytis leaf blight is moderate to high in the Holland Marsh based on BOTCAST (predicts the risk of Botrytis leaf blight in onions). Purple blotch and Stemphylium leaf blight of onions have been observed in some onions fields around the Holland Marsh.

Peak flight of 2nd generation cabbage maggot flies has likely started in London and Ridgetown areas.

The second generation of carrot rust flies will likely start emerging in the Windsor area in the next 5-7 days. Around the Holland Marsh, carrot rust fly activity is moderate to high in some locations. Based on sticky trap counts, treatment thresholds are 0.1 and 0.2 flies/trap/day for fresh market and processing carrots, respectively. Aster leafhoppers have been caught on sticky traps in the Holland Marsh, but at low levels. We’ve also seen some active in carrots crops in the Southwest parts of the province (based on a quick field walk with a sweep net). Be sure to monitor for leafhoppers in aster yellows susceptible crops.

Area

Onion Maggot (base 4)

Cabbage Maggot (base 6)

Carrot Rust Fly (base 3)

Carrot Weevil (base 7)

As of

Bradford/Holland Marsh*

991.5

n/a

1079.9

744.4

08/07/2013
London

1005.4

836.1

1093.7

757.9

08/07/2013
Wellington

897.0

735.9

982.9

660.2

08/07/2013
Windsor

1162.6

985.2

1255.2

900.5

08/07/2013
Thedford

987.1

821.6

1075.2

746.6

08/07/2013
Delhi

971.9

807.1

1059.4

729.3

08/07/2013
Ridgetown

1008.4

841.6

1097.1

761.2

08/07/2013

 

Area

Tarnished Plant Bug (base 12)

Leafhopper (base 9)

GDD (base 5)

As of

Bradford/Holland Marsh*

396.4

596.5

906.9

08/07/2013
London

405.2

609.2

919.2

08/07/2013
Wellington

324.3

516.2

814.1

08/07/2013
Windsor

520.5

739.9

1072.6

08/07/2013
Thedford

401.4

601.2

901.8

08/07/2013
Delhi

381

580.2

887.6

08/07/2013
Ridgetown

414.2

614.1

923.4

08/07/2013

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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