hi i have a main crop called picasso planted in late april i noticed only a few flowers on sume of the plants b4 the rain came and now the leaves are going yellow and brown but on the potato plants that are still nice and green i have noticed that sume of the leaves are going brown and curling under there is blight on are allotment so i have been told so could this b blight or is it just to much water so wat do you think blight or not as i have never seen blight b4
Have a look at wilko`s posting on blight on this page. The photo shows classic blight symptoms and appearance. The blight starts as the smallish black (or rather purplish) spots on the upper sides of the leaves, while the underside of the leaf under the black spot shows a slightly furry grey patch. The small black spots steadily grow, the leaf often then starts to yellow, and brown dead patches appear, usually where the edges of the enlarged spots meet the leaf margins.
However, the symptoms you described are not necessarily indicative of blight. The plants whose leaves are going yellow and brown may well simply be dying back, while the leaves curling and growing brown (particularly at the leaf margins) could be a symptom of temporary nutrient imbalance caused by the constant rain. The only way to be sure is to examine the plants carefully for the blackish spots shown in wilko`s photo - every such spot shows that a fungus spore has landed there and taken root in the leaf. If there are NO such spots then it is most unlikely to be blight.
In any event, you would be wise to spray as soon as possible with either Bordeaux Mixture or Dithane 945 to try and control the spread.
thanks will look in the morning will look at wilko page
We have blight on our allotment too I think its pretty general this year. The leaves develop brown spots and then it goes down the shoot to the potato and the potato shrivels. I have been told to cut the tops off the potato this stops blight getting into the potato and then you can dig them up as you need them. This we have done and so far so good we have had masses of potato's Last weekend we dug up1 cwt. of potato's from just 5 short rows of our main crop.
Yours Billie
Leaves tend to die back and shrivel leaving obviously dying stems. If you see this, assume blight. Early stages involve brown patches on stems and leaves.