Not blight?

[bazzaboy]

2 years ago on our allotments we had the scare of potato blight symptoms, worried folk used Bordeaux Mixture, removed top growth, harvested immediately etc.... The strange thing was no crop was lost so we all concluded "not blight" but something else. This year the same thing has happened.... stems have quite suddenly collapsed, leaves have gone brown and crisp (see photo) it looks a mess but again the crop seems unaffected. It's across all our allotments but no equivalent sign on same varieties being grown at home which are still green and generally in good shape. My lottie neighbour has named it "dry blight" but that doesn't seem to exist. Interesting that even the wonderful JBA Seed Potato company can mis-diagnose blight - see
How to test for BLIGHT - YouTube
In this case the plant collapses, turns brown, leaves go crisp.... but no visible effects on the potato crop. So what is it? Premature ageing?

[Bigmallly]

It's understandable how it can be mistaken as blight.

[bazzaboy]

Probably should have said that our allotments are on very heavy clay soil. Of course individuals over time have made areas more workable and friable, but the general state remains very solid. This recent hot weather can make the surface as hard as concrete, a couple of inches down it will mercifully still be damp. This is one aspect that's very different to the potatoes growing at home in bags of compost which retain their green active growth.

[Bill HH]

I think the most likely cause is lack of water. Today I went to pull some spring onions from a container but it was so dry they were snapping off. so I put the hose in the container and went to do something else. When I returned it was overflowing and water was pouring from the bottom. Thing is I then pulled some onions and an inch down the soil was still biscuit dry!!!!

[Penellype]

Another interesting video https://www.youtube.com/watch?v=aA4PuEKaQpY

Right at the end is a picture of a plant suffering from drought stress, which looks absolutely identical to the leaves on my desiree potatoes, and very similar indeed to blight. I have been watering them at least once and sometimes twice a day, but its been so hot and dry here that even that has clearly not been enough.

The video also gives a simple, cheap test for blight using a plastic bag and some damp kitchen towel.

[Potstubsdustbins]

Does this sound anything like your problem.

The first symptom is a yellowing of the leaves, they then turn brown and brittle, growth is stunted.

If so I would have your soil tested form lack of magnesium.

[teakdesk]

Another interesting video https://www.youtube.com/watch?v=aA4PuEKaQpY


The video also gives a simple, cheap test for blight using a plastic bag and some damp kitchen towel.

That's a great video Penellype!

Thanks, I'm going to save that one!

[bazzaboy]

Many thanks for suggestions and the informative tape.... Yes very possibly drought related as we have no water supply on the allotments and though I take 100 litres or so on most trips down there (gets heavy!) it's not for potatoes.... But the strange thing is the potatoes at home, which I don't water either, are fine.... This week I'm watering a lottie neighbour's greenhouse as they're away on hols for a week and their tomatoes, which certainly don't lack water, are now showing signs of it as well... It's def not what the videotape calls "Late Blight" as it doesn't seem to affect the fruit/tubers (at least it doesn't cause them to rot, it may well restrict quantity and size). So it's not devastating, just a bit disappointing that this year's potato crop, Early 1, 2 and Main, which looked so good earlier on and were the best I've ever managed, 17 varieties.... all look a mess now! Duh! Oh well, such is life, will repair tomorrow.....