Potato problem - stem rot?

[Svea]

i have one sick looking potato plant in my two rows. this plant has for the past 10 days or so looked much paler than its friends, this morning it looked decidedly yellowish, so i pulled up one of the 'wilted' stems - and found some kind of rot at the base of the stem. the stem is brown and shrivelled. four more such stems were pulled up, all the same.

what is it, and should i be worried?
as a point of interest, the same 'potato' seems to have produced two new very healthy looking stems. to compensate???

ideas, please.
svea

[Svea]

[DolphinGarden]

Svea,

see my other post re: potato blight

Ciaran

[Kepouros]

If the base of the stem is blackish brown, or purplish brown, it sounds very much like blackleg.  If it is indeed blackleg, and you have grown potatoes before without seeing it then it is almost certainly due to an infected seed.

There is no cure for blackleg, and the only treatment is to dig up every bit of the plant and destroy it.  If it has already formed small potatoes they will probably look o.k. but they aren`t - if they are left in the soil they will perpetuate the infection, and if you eat them they won`t taste very good.

Normal 4 year rotation will stop it recurring (unless you buy more infected seed)

[Svea]

thanks for the help. will dig up the potatoes today or tomorrow. how quickl and far does it spread? the plants to the left and right of it seem to be unaffected (at the moment, at least).

this is my first year at the allotment and while i 'tried' to put potatoes where there weren't any the previous year, it's only a guess. so who knows what was in the soil. next year's pots will be grown in a certified potato disease free bed ;D

thanks
svea

[Kepouros]

Don`t panic Svea.  It won`t spread through the soil from plant to plant like a contagious disease.

Basically it`s a soil borne pathogen which is present in many soils, but usually in such small concentration that it doesn`t cause any problems as long as a normal 4 year rotation is maintained.   However, seed potatoes grown on more tainted land will carry the disease with them, which is why I asked whether you had every experienced it before - it`s more than likely that you simply got a tainted seed.

Only a soil analysis can tell definitely whether you have it in the soil or not, but keep a close eye on the rest of the crop and root out any more which are definitely affected.  If you only use certified Scottish seed in future it probably won`t happen again - if it does you will can be fairly sure that it`s your soil to blame and not the seed.

I too had a similar experience after 50 years growing potatoes without problems, but I changed my seed supplier and the problem has not recurred.

[Svea]

thank you.
new to this growing business (nay, hobby ;)) and don't know what spreads how quickly and far yet :)

thanks
svea

[RSJK]

I have the same problem with just one variety of potato which is Accent, out of about 40 potatoes planted there is about 12 which are infected with blackleg,  I thought certified seed was checked for these  faults before they were put into circulation, Iam very dissapointed with the seed firm for not checking these things.
          >:( >:(

[Kepouros]

Richard, unless you bought Certified Scottish Seed your Accent probably weren`t certified by anybody.  A lot of the seed sold by the major mail order suppliers can have been grown anywhere in England (and themselves grown from imported seed), and although theoretically there are supposed to be certain standards these are nothing like as rigorously applied as with Scottish Certified Seed.  You may recall that last year a farmer in Wales managed to raise (from imported seed) and sell as seed several hundred tons of potatoes infected with Potato Ring Disease which then had to be traced and recalled for destruction.