[Carollan]

Spuds,

My first early row is fine.....digging up and eating them for the last couple of weeks.No blemishes or slugs amazingly.They were put in quite late,but the ground had started to warm up a little.

Then we had the rain.Oh how it rained.The water sat in puddles on the ground and ran in a brook down 2 sides of the allotment.The maincrop spuds that had started to come up have since developed wilt.Other spuds went rotten in the soil ,it stayed wet for so long.

Will the affected soil be a no-no for spuds in the next 5 years? I`ve worked out a rotation system to keep them off that side of the allotment.Or would I be alright in 3 years if the weather is more `normal`?

[mumofstig]

IMO 3 years should be fine

[solway cropper]

Up here in Cumbria, which is supposed to be the wettest county in England, we've had nothing like that. Hardly enough rain to keep the water butts filled.

Anyway, are you sure the spud problem is due to the water or disease? Blackleg and PCN seem to have been much more prevalent this year.

[Carollan]

Solway,I'll have a look for PCN tomorrow,it's not blackleg ,I had that last year!

thankyou for that,I hadn't heard of PCN before :blink:
so much to learn.........

 

[Salmo]

I would entirely blame the waterlogged conditions. As well as just rotting the wet conditions may well have encouraged blackleg.

Potato cyst nematodes, PCN, are unlikely unless yours is an old allotment where too many potatoes have been grown consistently. If you lift the plants carefully you should be able to see tiny, yellow/brown, lemon shaped cysts attached to the fiberous roots. Use a hand lens. Drop the plant and some earth in water and the cysts float.(google images will show you what to look for). In any case a 2 year break should be enough to control it. It is usually worse in dry conditions.

[JayG]

PCN is alternatively called "Potato eelworm", which often leads to confusion because the "worm" is so tiny and buried in the root tissue you can't see them.

You can quite easily see the cysts on the roots though, and sometimes on the actual spuds too - they are tiny round structures smaller than a pinhead and vary from almost white through to brown depending on the type of PCN (there are at least 2  ) and also how "mature" they are.

Having said all that, your spuds could well be a victim of excessive waterlogging.

[JayG]

Oops - too late AGAIN! 

Luckily I appear to agree with everything Salmo has said, apart from PCN persistence in the soil - although numbers will reduce slowly without a host plant to re-build the population, I believe they can remain in sufficient numbers to cause re-infection even after 10 years.

Growing resistant varieties helps, and luckily Lady Chrystl is one of them, although few varieties have much resistance to both forms of PCN, and it's not that easy to tell which one you've got.

[goodtogrow]

Thank you for the very knowledgeable replies.

I rely entirely on good soil to produce vigour in the plants, so that they can combat pests themselves.  I don't always get a good crop, but I never lose the entire crop either.

Do people lose their entire crop to pests and disease - blight aside?  Am I just lucky to have healthy soil?

[JayG]

Blackleg is fatal to the plant, PCN severely reduces the crop because the plant is literally having the life slowly sucked out of it by the eelworms which have invaded the root system. Fortunately, neither of them seem to affect every plant, or at least not equally in the case of PCN, and there are varieties which have some resistance.

I've got both problems in my soil, which when I moved here 14 years ago was used only for ornamental heathers, hebes and the like, and I have only ever planted certified seed potatoes. Makes you wonder!