A few quezzies ???
Does this just affect cabbages?
How do you guys protect against it?
Is it really prolific or can I just wing it and hope for the best?
As extracted from my website;
The small white maggots of this fly live in the soil and eat the roots of cabbages and other brassicas.
Infested plants wilt, especially in dry weather, and young plants may be killed.
The adult flies are active in April and May when they lay their eggs on or near plant stems at soil level.
Three generations of adults develop during the summer and attacks may persist until mid-September.
In many areas this pest is now resistant to insecticides that formerly gave good control.
A suitable soil drench to established transplanted seedlings may be the most effective insecticide.
You can use purpose made collars that fit around the stem of plants.
My preferred method is the drenching at planting out time I use Armillatox (mixed as per label)
This has a Jeyes fluid smell and personally I think it is this that deters the fly laying its eggs in the vicinity.
I hope this answers your question!
http://tinyurl.com/yoo4s3
I use derris dust which is organic. It has always worked and I put some in the soil that I plant the seeds in, then in the soil that I use when planting, and then on the surface for good measure. A puffer pack seems to last for ages. I also use it on turnips and radishes, which are members of the same family, where it also deters flea beetles.
http://www.allaboutliverpool.com/allaboutallotments1_homepage.html
Definitely don't wing it.
I use the brassica collars .. cheap, extremely effective and environmentally friendly.
You could use small square pieces of old carpet instead, snipped appropriately so that they will snuggly fit around the base of the plant.
we use pieces of carpet underlay, snipped to the middle and used as a collar :)