Kitchen Garden Forum

I have a bad case of Leaf/Ring Spot on my Sprouting Broccoli (and Sprouts) which I have basically being ignoring in the hope that it would go away, and thinking that it was merely the time of year for yellowing leaves - black spot starting on the lower leaves, growing in size, leaves dying. In fact I only looked it up in Dr Hessayon today and discovered what it is. He says to burn the leaves (rather difficult!) and not to grow brassicas on the same spot next year - and dithane as a 'cure/preventative'.

As I have been gaily adding the many yellowing leaves which have been dying off to the compost, I wonder whether the resulting composting will be ok.

Anyone any suggestions as to what to do with existing plants and the compost? The whole situation seems to have arisen as a result of covering some plants to keep off the caterpillars - when it got wet the humidity caused the problem.

Hi Colin - humidity and lack of air movement would have done it.

If it is Brassica Ring Spot, you should see large rounded brown or purple spots, with concentric rings of black dots inside them or a black ring like a halo around the edge. If the spots are small and solid black or dark purple, it could be Brassica Dark Leaf Spot, which is not so bad.

In the case of the former, pull all the plants now and bag them them up for the bin. Not sure about your compost - you are risking it being full of dormant spores, so you might have to take a deep breath and get rid of that as well. If it's the latter, it's endemic and not that serious, so the compost should not pose a problem.

Sorry to be the bearer of bad news

Sue

Thanks Sue. Unfortunately it looks rather like the Brassica Ring Spot. The main plants affected seem to be the Sprouting Broccoli - various varieties - the Jerome Cauliflowers seem largely unaffected, the mature cabbages are ok, the Sprout leaves have mostly died off but again not too badly affected and the Sprouts themselves are ok.

Is there really no solution? What about Dithane or any Copper-based chemical like Bordeaux mixture or Cheshunt Compound? Or maybe a Jeyes solution would work? And is there really no Organic solution?

The advice about not putting things on the compost that have a problem, is something that I wonder if it is really necessary. After all, if you have it this year, then clearly the spores were already in the air, and were enabled to reproduce because of the local humid conditions. Therefore, since the spores are clearly there already, what is the point of burning diseased material? How will it make things better for next year, given that this year you presumably had "clean" compost and got it anyway?

It is something I do wonder about. Our garden was created from a paddock that has to be at least one-and-a-half miles from the nearest garden. Yet in our first year we had cabbage whites, potato blight, whitefly, aphids etc, and the roses were covered with blackspot. So it was all around in the air anyway. So what difference will it make, burning diseased material etc etc?? All the nasties are around anyway, just waiting for the ideal conditions to pounce; they are out there, lurking in the hedges and wild plants. .

So my gut feeling is that we might as well compost everything, and concentrate on growing our plants to be as strong as possible so they can resist the nasty!

You could try shaking hard some of the diseased leaves up with distilled water, then take a spoonful of that mix and shake it up hard with a further 100 spoonfuls of distilled water, and do this process a further 6 - 10 times, and then spray the plants with this solution next year. This would be a homoeopathic solution, that would jerk the plants, when sprayed, into resisting the disease themselves.
Alison

If it works at all Homeopathy works for chemicals, not spores which can breed!

looking through my 1955 (briefly revised 1964) "The Complete Vegetable Grower" by W E Shewell-Cooper, I find that he had only ever found this disease in Wales(!) and the south and south-west of England. He suggests composting the leaves and sprinkling them immediately with a fish fertilizer as an activator and aim not to grow members of the cabbage family on that piece of ground for three years. Also that it will attack cabbage but prefers broccoli - don't I know it!

Searching on the web I see that Amistar is recommended as a safe control, but is this for commercial use only? Johnboy, Allan, do you know anything about this?

peter wrote:If it works at all Homeopathy works for chemicals, not spores which can breed!

There are homoeopathic remedies made from viruses and bacteria, so I don't see why they shouldn't be made from fungi substances. Anyway, it does no harm to try, and might be quite fun, and interesting if it were to work.
Alison.

Hi Colin. Sorry about the delay in getting back to you - been too busy at work to allow much forum browsing time

The active ingredient in Amistar is azoxystrobin and there is no domestic product you can buy that uses this. As far as I know, the fungicides you can buy and that you mention are ineffective. The latin name for the disease is Mycosphaerella brassicicola, so you could try an internet search on that and see if you can get some more detailed info.

Most of these fungal diseases have quite a complex biology and produce different types of spores. If the advice is destroy the infected plants, it usually means the disease produces spores that can remain dormant in the soil for years as well as the wind borne instant infection types. You cut the chance of your plants getting the wind borne infection by reducing humidity and improving air flow. The chances of an infected plant being around when conditions are just right are therefore lower. The soil borne dormant spores just lurk until conditions favour them and then attack, hence the slash and burn method of control.

Hope this helps a bit.

Sue

Thanks for the info Sue. I have sprayed the non-flowering broccoli first with Cheshunt Compound which probably didn't do anything as I didn't include any wetting component, and then with a fungicide which was recommended for Leaf Spot - reading closer it said Celery Leaf Spot but I have tried it anyway. It may be having an effect, but maybe I am just being hopeful. With the weather as it is it is difficult to do anything outdoors at the moment.