Brown marks in spuds

[Medbury Gardens]

This potato was given to me as part of a collection from a old gardener who had advertised for someone to past it on,Its known as 'Stan Cloak',red skin with yellow eyes,inside is yellow and is a excellent baker/chipper.But in the 15 years i have grown it,it has all ways had these brown marks within the older spuds,not in the young tubulars.Its not rot as now 4 months after harvest the markings have not lead to any deterioration in storage.
Does anyone know what it is ??
Its the end of the road for Stan Cloak, i`m not going to grow it again, as i have been given 'Heather'to try this season as well i want to bulk up on 'mystery'(thanks for the name Tom)

Richard

[Tom Wagner]

http://tinyurl.com/5gznsk

SPRAIN OR INTERNAL RUST SPOT OF POTATO

This site has quite a bit of interesting comments on sprain

Next site:

http://tinyurl.com/6kozvb

Internal heat necrosis (IHN), a severe physiological disorder of near harvest and generally in the larger tubers first, is characterized by
spots or blotches that first appear toward the apical end of the tuber parenchyma but in severe cases may involve most of the parenchyma tissue.

Atlantic is a variety that does well for chip growers but is often cited as a susceptible variety. Seems to be a correlation between heat units and variety.

Heat necrosis, a discoloration of the tuber, is problematic in the hottest areas of the country.. Avoid it by growing early-season varieties and planting and harvesting before the hottest times of year.

The effect of the hot Israeli climate on tuber quality (Internal heat necrosis- IHN). See photo:
http://tinyurl.com/6hsh28

Control Measures: http://tinyurl.com/5qut4g

1. Add lime to acid soils.
2. Add of calcium to deficient soils.
3. Establish good vine growth to shade ground (row closure).
4. Don't store tubers in ground long after vine death.
5. Schedule irrigation for seasonal growth.

Hope this was of some help. Sorry that the Stan Cloak variety was a problem. I suggest that since the disorder is variety related, you may have to discard it unless the control measures help in the future.

When I find problems that are unsurmountable, I either don't plant a variety or just a hill or two. Rarely do I keep a clone alive within my collection more than a few years. If a variety does well for ten or more years I keep using the line for breeding and increase purposes. I can't maintain many 'weak' varieties for fear of spreading disease or subjecting on-going progenies with failure prone attributes.

Tom Wagner

[Medbury Gardens]

Thanks for that Tom,

Its does appear that Stan Cloak is very susceptible(IHN) as it doesn`t show up in any of the other spuds grow but also even though we live close to sea level,70kms and with two other valleys between us and the ocean,we dont get the extreme temps that say the mid US would get, we average summer daily highs 30 C -84 F with the odd day reaching 38 C-100 F.

If potatos are mounded that would increase soil temp,increasing the likelihood of (IHN) susceptibility,i plant all my potatos in rows close together 40cm apart and then covered with horse stable manure and sawdust, a mix 50-50, with another thin layer over the top mid summer to stop greening as they start growing through the surface,this method would keep the soil cooler.

The dissappointing part of maintaning the Stan Cloak variety all these years is that is its a great eating spud, only half of each plant show up the (IHN),its vigorous and high yieiding.
ohh welll bye bye stan

[cesarz]

Hi Richard,

I know its been 4 years since this thread finished but do you know if Stan Cloak potato is still around in NZ?

[Medbury Gardens]

Oh well done Cesar,we were talking last night and i mensoned to him that Kowiniwini had had the brown spots that plagued Stan Cloak in this thread,i have no idea if Stan Cloak is still about though
New Zealand had a very cloudy cool summer so heat would not have been a factor,also going by resent soil tests my PH is naturally around the 6.5 mark,other control measures i pretty much did carry out, as in the whole crop gets regular watering also i make sure there's good vine growth to shade the ground.
When i was digging Kowiniwini i kept each of the plants potatoes separate in its own pile and then went through at the end cutting open looking for plants that had little or none of these markings,thankfully there was a couple of plants that did so i'll grow from these next season, i don't really want to drop this variety from my collection as its such a lovely eating spud, it had been a really poor producer for over 15+ years then three years ago i started to get large crops which came from just one plant out of the blue.
Question is,will selecting be a waste of time,or is there some other way i can control this problem i wonder.