[WeeJo]

Hi Guys

This is my first year on the allotment and I noticed that my potato plants have small brown spots on some of the leaves (not all).

I did spray an anti fungicide about a week ago and I'm hoping that it's not blight.  I think maybe a mineral deficiency (magnesium perhaps).   

I'm digging up all my earlies today, just to be sure, but I have King Edwards which should be in the ground for quite a while yet and I don't want to lose them to the dreaded blight.

Any suggestions on how to tell the difference and what I can do, if anything to save some crops if it is the early stages of early blight?

All advice more than welcome.

[Yorkie]

Have a look at this thread, which is found in the Growing Section - FAQs sub board 

http://chat.allotment-garden.org/index.php?topic=56717.0

[WeeJo]

Thanks Yorkie,

I've checked out some photos but it doesn't look like blight to me, so far.  But As Ive never seen it in real life I am not convinced.  It's so hard to tell.   Also otherwise the plants are looking really healthy.

I thought that I might cut of and detroy the affected leaves and see if that helps.  And I have sprayed with a vegetable fungicide spray.  Plus I'm going to put down a general vegetable feed to help with the nutirient side of things.

Aside from that I might just start praying to the potato gods!   

Worst case scenario, how early can you dig up king edwards?   

[arugula]

King Edwards are a maincrop and as such, aren't normally harvested until September. When did you plant them? They take 15-22 weeks to mature into a decent crop.

[WeeJo]

I'm lifting my charlottes this weekend. (Is it safe to eat them after spraying the plant with fungicide in the last few days?)

I planted my Kind Edwards in early May, so I gues I'd expect them to be lifted about late September onwards?

[DD.]

I'm lifting my charlottes this weekend. (Is it safe to eat them after spraying the plant with fungicide in the last few days?)

What does it say on the packet? That is what you should go on, not what someone tells you.

With the stuff I use the harvest interval is longer than a few days.

[WeeJo]

Thanks for the advice guys.  I'll check the packet when I go up later just to be sure.  No point poisoning the family out of fear of blight, eh?

I'll maybe take a photo of it later and post for further diagnosis of the suspected blight.
Hopefully I'll be lucky.

[mumofstig]

You can buy a test kit to confirm whether it's blight or not
http://www.plantsbypost.com/testing-kits/potato-and-tomato-blight-testing-kit.html

or here
http://www.jbaseedpotatoes.co.uk/blight-spray/blight-tester-kit-p231.html

[totalnovice]

or you can watch your neigbours, if they start panicing then its blight

[mumofstig]

the OBs panic at first sign of anything on their spuds...............even frost damage was called blight earlier this year
So panic means nothing 

[totalnovice]

I know but it is still funny to watch.  :happy:

[Salmo]

Magnesium defficiency and blight are not easy to distinguish. If the brown spots develop rapidly on humid days, and if there is mould on the back of the spots, it is blight.

Sprays are preventative and do not get rid of blight once it is established. They will slow down the spread.

The safest approach is to cut off the tops once your crop is infected. If this is done in good time it will prevent spores going on to the soil and infecting the tubers. You should then wait 2 weeks before lifting for storeage. You can dig them when you like for immediate use.

Cutting off tops may lose a bit of yield but it is better than blight in the tubers which can mean losing the whole crop.

[mike1987]

i was told if the spots have a halo on the underside of the leaf then its blight also it has a obvious smell apparntly but as thes is my first year with spuds in the ground i wouldnt know what it smells like

also i have a Magnesium defficiency wich i thaught was blight lucky for me one of the old boys told me it wasnt and gave me a watering can with epsom salts in it