CROP MONITOR

Return to Spring/Summer Pests 2005

2004/2005 SURVEY: SPRING/SUMMER PEST ASSESSMENT 2005

Unsprayed crops at mid-late flowering were inspected for Cabbage Seed Weevil and Cabbage Aphid

It is after the mid-late flowering growth stage that the Cabbage Seed Weevil begins laying its eggs on the pods. Cabbage aphid populations should also be visible at this growth stage if they are going to cause a problem.

Site Location	Number of sites	Cabbage Seed Weevil per plant per site	Maximum Cabbage Seed Weevil per plant
Bedfordshire	1	0.00	0.00
Cambridgeshire	2	0.00	0.00
Kent	3	0.28	0.40
Hampshire	6	0.49	1.30
Lincs	5	0.08	0.20
Northants	2	0.08	0.15
Oxfordshire	4	0.30	0.75
Shropshire	4	0.05	0.15
Somerset	9	0.26	0.65
Staffs	4	0.14	0.25
Suffolk	6	0.17	0.40
Wales	4	0.15	0.40
Warwickshire	2	0.10	0.15
Yorkshire	10	0.17	0.35
mean of all 62 sites		0.19	1.30

Only two sites have had any visible infestation of cabbage aphid. There was one in Wales and one in Yorkshire, but they were way below the published threshold of 13% of racemes infested.

Thresholds
Published thresholds are 2 per plant, unless the site has a history of Brassica Pod Midge problems. If this is the case the threshold drops to 1 per plant.

Number of sites with more than 2 cabbage seed weevil per plant:	0 (0%)
Number of sites with more than 1 cabbage seed weevil per plant:	1 (2%)

	RAPID ACCESS TO THE LATEST REGIONAL CROP PEST AND DISEASE LEVELS
CropMonitor > Winter Oilseed rape > National Surveys