Topic: Oh er... whats up with my spuds?!

[Sparky]

Just popped down to the lottie to pick some broad beans and noticed my potatoes have black/brown spots on the leaves.  :o
Is this the dreaded blight?  :-\
If it is is there anything i can do to stop it?  It is on my first earlies but i can't see any one the maincrop yet!  Can i still eat them?!?  Help!!! ??? ??? ??? ???

[sandersj89]

Probally not blight, that appears around the edges of leaves first and looks more like a mildew.

The spots you are seeing is a virus of some sort I believe. The leaves will start to yellow and die back too.

The spuds are fine to eat though.

Jerry

[tim]

Probably!
But look up photos of the blight - it's on the edges of the leaves - can't cure it but, if you've plenty of potatoes & it is blight, cut down the haulms & dispose of them. & spray the rest with Bordeaux mixture each week.  Dig for eating but, if you want to store, leave 3 weeks before lifting. = Tim

[philcooper]

Sparky,

Your profile, doesn't say where you are. There's info at http://www.potatocrop.com/blight/ on where blight is currently in the UK. If you let me know your location I can get you the current conditions

There's more on blight at http://biology.bangor.ac.uk/~bss081/blight_beginners.html

Meanwhile Tim's advice is good - off with the effected haulms and spray the rest with Bordeau or Murphy's Traditional Copper Fungicide every week or every time it rains whichever happens first

Phil

[jo2]

Glad you asked, one of mine has got funny brown speckles on the leaves too. Looks otherwise healthy-will get the fungacide out now.
Doesn't look anything like the blight photos-more like freckles.

[philcooper]

Jo,

If you have got blight, you can forget fungicide, it's too late. You can only chop the tops off the affected plants

The copper based chermicals produce a protective film on the leaves to prevent the spores taking hold, so they have to be applied before signs of blight on the plant you are spraying.

They also need to be reapplied every week or when rail has washed them off

phil

[Sparky]

Thanks everyone for your help.  My allotment is in sunny Wigan and believe it or not it has been pretty hot and humid here, alternating with quite a bit of rain!  The leaves don't seem to be furry, just lots of brown spots.  The spuds taste fine though so as we weren't going to store them we are just carrying on eating them and hoping they'll stay alright til we've munched them all.  We have cut off the spotty leaves though to try and stop whatever it is from spreading to our maincrop spuds.  Can we compost the spotty leaves or are we best to bin them?

Sparky

[Mrs Ava]

I would bin them Sparky as you never know and you don't want to pollute your compost and spread a possible disease all over your plot.

[philcooper]

Sparky,

I've just checked and Wigan has not had the high temp/humidity levels (11degrees and 90% for 24 hours) that promote the growth of blight since early June

Phil

[micsmum]

Some of my earlies (Rocket) have brown spots on the leaves and the leaves of 2 have turned yellow so dug them last night. Not a huge yield but they look OK apart from the odd hollow one which looks like slug damage!

[philcooper]

Micsmum,

If the disease is (leaf) blight it will take several weeks to effect the tubers (tuber blight)

As has been said before for earlies, cut off the affected tops and dig up when you need them

Phil

[tim]

micsmum et al. Spots?  Blight? - too lazy to find better photos. = Tim

[micsmum]

Its the second piccy Tim and Phil - the roses in my garden seem to hav a similar looking ailment but the spots are a darker brown!

[philcooper]

What you see on roses at this time of year is black spot - another fungal disease but nout directly related.

There's good blight pictures and words to help at http://vegetablemdonline.ppath.cornell.edu/factsheets/Potato_LateBlt1983.htm

Phil