What is the indirect effect of midges on cabbages? Think about biological control?

Question

What is the indirect effect of midges on cabbages? Think about biological control?

Answer 1

Description of damage:

No head will form if damage occurs to a young plant

Young shoots and leaf stalks may be swollen, distorted and crinkled.

Heart leaves are crinkled and crumpled.

Brown scarring on the head and along leaf stalks

If the main stem is destroyed, the development of secondary stems can result in a multi-stem plant.

                            Apart from that economy of state is affected cos of loss of crops.

For figures refer :

http://www.massnrc.org/pests/pestFAQshee...

Biological control:

Monitoring is best achieved using commercially available swede midge pheromone traps. The swede midge pheromone is a s*x pheromone that attracts male midges. Research in Ontario has shown that white Jackson traps are the most effective at capturing swede midge. They should be hung from stakes with the bottom of the trap set 30 cm above the soil surface. Do not place traps higher than 30 cm above the ground, as swede midge fly fairly close to the ground. The pheromone lure is attached to a piece of cardboard, which can then be stapled to the inside roof of the trap body. The lure is effective for approximately 4 weeks. Place three to four pheromone traps per field at least 50 m apart. Traps can be placed within the field or in the first few rows for ease of monitoring. Check pheromone traps and count midges two or three times a week to optimize timing of insecticide applications.

For other methods like Greenhouse Sanitation, Crop Rotation,Crop Selection,Field Sanitation,Planting and Harvesting Dates,Insecticide Spray Timing  refer to

http://www.omafra.gov.on.ca/english/crop...