[anchorman]

Hello all, it's  been a while.
I think I finally cracked the problem of growing Brassicas from seed into healthy plants. Too wet was the cause.
However, I've got a problem with young Brussells sprouts. Doric and Brodie. They were planted on the plot a few weeks ago and were doing fine. The lower leaves are green and healthy and the plants rapidly established. However  new leaves higher up and growing from the centre are curling up  and have developed purple edges. Also there is what looks like black deposits on the undersides and in the joints between stem and leaf. It's easily dislodged but something is going very wrong.
The ground has been well fed and limed prior to planting  fish blood and bonemeal applied.
The soil pH us now around 6 so I've scattered a bit more lime around the plants to raise pH a bit more.
All this started when the plants reached about 10 inches high and all the plants under the Sprout cage are affected.
I've given them a spray with Resolver  in the hope it's a fungus of some sort, and a liquid feed high in Nitrogen.
Any advice is appreciated
Thanks.

[Hampshire Hog]

Have you seen any whiteflies? Cabbage whitefly can result in a black deposit on leaves which sounds similar to your description. Good luck HH

[anchorman]

Thanks HH. Yes, there are a few but usually I see them later. It's the new leaf distortion and blueish tinge that's worrying me. I just hope it's not club root. We don't seem to suffer that on our plots...YET!  Fortunately I have more in a cold frame coming along which I could plant in another space. I'm disappointed tho' it's taken me years to cultivate really good brassicas from seed and now  something is causing trouble in brussells.

[Gardener and Rabbit]

The blue/purple tinge could be a sign of cabbage root fly, and affected plants will often wilt & collapse eventually because their roots are being eaten away. If you lift a plant and find small white maggots eating into the roots that would confirm it. 

G&R