Kitchen Garden Forum

Having studied potato and tomato late-blight for about 40 years, I would like to make some points about Sarpo spuds which may be of interest and might dispel some myths. Please contact the Trust if you want more detail: http://www.sarvari-trust.org

HOW BLIGHT WORKS: Phytophthora infestans can only grow on living tissue of some solanaceous plants and can survive on tubers (seed or unharvested tubers or outgrade dumps in gardens and farms). In summer spores spread in the wind from early infections over long distances. Isolated gardens are not immune. Very rarely, some strains of blight can hybridise to form oospores which can survive in soil or cold compost heaps to infect a new crop. New strains of blight are generated from oospores. Blue 13 and Pink 6 strains are more aggressive strains which have become common since 2005. Tomato stains can differ from potato strains but not always. Reports of blight on pepper and aubergine are very rare. I don’t think that Goji plants transmitted blight to tomato but I could be wrong. I would like to see diseased Gogi plants to confirm that it is really late blight disease. Blight has been reported on peppers and aubergine but very rarely.

JERSEY has a blight problem like other UK potato regions. Most growers there and elsewhere prevent the rapid increase of blight by very regular use of fungicides. Potatoes are grown in most months of the year in Jersey so growers cannot avoid the blight.

WEATHER: Blight infection and spread depends on warm weather and leaf wetness. Some growers in drier, cooler or windy areas get less blight or no blight but when weather is wet (the last 3 seasons) blight is widespread but is sometimes not noticed as it is often confused with ripening foliage. The wet weather has meant that blight is more often in the news.

SPREAD FROM ORGANICS? Unsprayed crops, if badly infected, generate massive quantities of spores which can drift in the wind to infect unprotected crops for miles around. In the Netherlands, growers are fined if they do not destroy a crop with more than a small quantity of blight. Most gardeners and small growers (organic or “inorganic”) use few if any sprays. So responsible organic growing will not spread the disease.

SPRAYS: Copper based sprays are still legal to use but are highly toxic in the environment and many organic growers will not use them. Many argue that some synthetic sprays are more benign. Dithane for gardeners will be withdrawn this summer. Sprays prepared from plant extracts are at a developmental stage and could be available soon.

HOW RESISTANT ARE THEY: Most Sarpo varieties have remained resistant to the newest strains of blight including Blue 13. Sarpo Mira is still more resistant than any other conventionally bred variety. I doubt if the new GM varieties have higher resistance but maybe we shall see. Our varieties have very high blight resistance – quite high enough for the commercial grower. The small amount of disease in trials is the result of unusually high blight pressures, which we sometimes encourage by misting. This small amount has little or no effect on yield. Low input means less costly to grow and increased profit margins for commercial growing. They were bred initially in Hungary to feed the former Soviet Union but have been refined over the last 40 years. The slow uptake here by commercial growers is a result of our slow and costly multiplication of seed and lack of expensive marketing to create a market. Just look at what advertising has done for Rooster.

HORTICULTURAL SALES Thanks to efficient promotion by Thompson and Morgan, our first two varieties are grown in allotments and gardens up and down the country. The 4 newest Sarpo varieties ARE approved for sale (they are on general release). But seed will be in short supply until we are able to multiply stocks – costly and time consuming. A small levy on each of their sales is donated to the Sarvari Research Trust.

TASTE in potatoes is very subjective. Soils and climate and maturity of tubers do influence taste. I have customers who rate Axona very highly – like a good Kerr’s Pink or better than Rooster. Some say they taste too stongly of potato, others that they are tasteless. The first two we introduced, Sarpo Mira and Axona, are high dry matter spuds selected for use as chips, bakers and mash – they make excellent fries. The taste of our 4 new varieties as assessed at our open days are much praised but some like one and some like another best. Some of the new ones have lower dry matter than Sarpo Mira and Axona and suit people reared on waxy potatoes.

And GM? As we are told by the supermarkets, our varieties are not Maris Piper or Desiree, the darlings of the multiples. The industry is hooked on these and a few others that it knows well and knows will sell. So putting a potato resistance gene into Piper instantly creates a variety with an already developed market. The high tech molecular genetic approach is generously funded by government and private foundations too. There is not much support for conventional breeders whose needs are relatively modest compared to those of GMers. The Sarvari Research Trust survives (only just) but spends a lot of valuable time trying to raise funds. Please send donations ………..

David Shaw, Director SRT

Hello Kitchen Garden.

Great that this forum is so active and that some really informative posts are coming up (thanks David for the clarification on Sarpo spuds). A quick point about our level of participation however is that we will not always be able to respond as frequently or in as much detail as we would like. As a charity we do not have the time nor resources to address every point raised on every forum on the net – wish that we did! Last time we posted links because they give extensive information that we would not have the time to re-write - we will do the same again where relevant.

To try and address some of the points;
That a healthy plant or person are better able to fight off diseases is one of the founding principles of organic farming and why we are dedicated to promoting healthy soil. A strong, healthy crop grown in biologically active soil will be as resistant to as wide a range of diseases as possible – extensive research has shown this (available on our GM reports page http://www.soilassociation.org/Whyorgan ... fault.aspx). This contrasts starkly to the GM varieties, where resistance breaks down relatively quickly as the blight mutates. GM is a sticking plaster technology that attempts to fix one problem in the growing system rather than fixing the whole system.

One of the much touted advantages of the new GM potato is an end to the fungicides which are currently used heavily to control late blight on main crop potatoes. This is not necessarily the case. Other diseases such as stem canker, black scurf, silver scurf and black dot, also require fungicide usage. Therefore elimination of late blight does not necessarily mean the end to fungicide use on potatoes. In 2004 nearly 1.3 million kg of fungicide were sprayed on non-organic potato crops. Data of how much was applied specifically for late blight are not available via the Pesticides Safety Directorate’s web site.

Transgenic/cisgenic GM:
Transgenic - Our opposition to transgenic GM, based on the reports also available on our website is that as well as potential risks to wildlife and human health, it has consistently underperformed, despite claims from the biotech industry that it is necessary to meet the ‘perfect storm’ of climate change, resource depletion and a growing global population.

Despite over 20 years of investment, transgenic GM has not increased crop yields. At present only 4 per cent of the world’s agricultural land is GM-farmed, 2 per cent of this in the USA. Where the technology is used, there is increasing evidence that farmers are finding that it does not deliver as promised, and in some cases may lead to increased use of pesticides.

Cisgenic - Any positive results from cisgenic GM could also be achieved through Marker Assisted Selection. MAS has already been used to successfully produce disease resistance varieties in a range of crops including barley, wheat and beans, and drought-tolerance in aerobic rice, as well as a yield-increasing tomato. This technology uses genetic markers to identify the genetic sequence for a desired trait, such as drought-resistance, in a crop. Researchers then look for the marker with a rapid DNA test in the offspring plants and can know immediately which ones have the desired trait and which ones do not. These techniques should be supported, as part of far-reaching changes to our food and farming systems based on agro-ecological and organic farming, of which GM technology has no part.

The Greenpeace report "Smart Breeding Marker-Assisted Selection: A non-invasive biotechnology alternative to genetic engineering of plant varieties" is at http://www.greenpeace.org/international ... -breeding/

Here are a couple of potentially useful links on the subject:
http://www.patnsteph.net/weblog/2010/06 ... to-trials/
http://www.gmfreeze.org/uploads/GM_Spud ... iefing.pdf

I hope this goes some way to answering your questions. We cannot promise to be across this forum all the time. If you are interested in our standards – please do read through the reports and advice pages on our website - you’ll find all the information there in much more detail than we can go into now.
http://www.soilassociation.org/Farmersg ... fault.aspx
http://www.soilassociation.org/Whyorgan ... fault.aspx

If you are interested in going organic and want the expert advice that our specialist teams offer on subjects such as blight, our Trade And Producer Support Team are there for that purpose: http://www.soilassociation.org/Farmersg ... fault.aspx
If you are already an organic farmer licensed by us, your certification officer is there to offer you this kind of advice and support: http://www.soilassociation.org/Certific ... fault.aspx

alan refail wrote:

SoilAssociation wrote:Regarding potato blight, we would argue that a strong, healthy crop grown in biologically active soil will be better able to resist blight and we would encourage all growers to focus on best practice.

That is a sweeping statement; could you point us in the direction of trials/research which lead to this conclusion? I garden 100% organically, do not spray and usually avoid blight by planting as early as I dare and harvesting before the main blight season. Mind you, I am only growing for two people and live in a mild area of Wales.
I see no reason why genetically modified blight-resistant potatoes could not be grown according to organic methods; unless, of course, you say that GM is incompatible with organic methods. In which case one might ask you why? What is your understanding of genetic modification, both transgenic and cisgenic?

Hi SA

Yet more links which I do not find useful! It would be more in your association's interest if you could answer the question: where is the research to prove/suggest that "a strong, healthy crop grown in biologically active soil will be better able to resist blight "?

SA Quote:

'This contrasts starkly to the GM varieties, where resistance breaks down relatively quickly as the blight mutates. GM is a sticking plaster technology that attempts to fix one problem in the growing system rather than fixing the whole system.'

I really don't understand how why this should be so. Another sweeping statement?

Well, Colin bach, it looks as though if you get blight it'll be your own fault, for not following SA rules of best practice

More seriously, though, I would prefer to get answers from them rather than irrelevant links. Gives me the feeling they don't really have any research to support their claims.

SoilAssociation wrote:
Regarding potato blight, we would argue that a strong, healthy crop grown in biologically active soil will be better able to resist blight and we would encourage all growers to focus on best practice.

The evidence that I am aware of suggests the opposite - as does my own experience. The blight pathogen is happiest when it is feeding off a well grown plant grown in a 'healthy soil'. When we want to encourage blight infection in our trials at SRT we make sure that we have plenty of nutrients in the soil and that we correct any nutrient deficiency.

When plants are under stress (drought, or low nutrients or cold or heat etc etc) they turn on a battery of genes which combat the stress. Some of these genes make the plant more resistant to disease. I have often observed that plants under nutrient stress (often happens in organic plantings but also in conventional plantings) are less affected by blight, lesions are smaller and sporulation on foliage is less.

In fact in an unhealthy soil, infection by a range of weak pathogens in the soil can induce plants to become more resistant, again by turning on these stress related genes. This is well researched and is referred to as Systemic Acquired Resistance (SAR). It is a kind of plant immunisation.

In conclusion, a well managed organic or conventional crop of potatoes is high yielding but is highly susceptible to blight.


Re the comment
Any positive results from cisgenic GM could also be achieved through Marker Assisted Selection (MAS).
This is not so. The whole point of GM is that an established variety not resistant to a pathogen can be made resistant by adding a resistance gene. MAS, which I have used to help breed Downy Mildew resistant millet, can help to make conventional breeding quicker and more accurate but it cannot make a Maris Piper resistant to blight.

Our biggest problem at SRT is that our resistant potato varieties are not similar enough to the industry-standard varieties because we do not use GM.

Sorry if I am duplicating previous comments on this topic.

David

I for one find your experiences interesting and your comments are very welcome.

Barney

Hi David,
I am sure that the vast majority of Forum contributors are more than grateful for your magnificent contribution and may there be many more.
There are many things I would like to ask you but right now seems it would be inappropriate.
This is quite a monumental occasion on this Forum.
I thank you so much.
Sincerely,
JB.

With the total world planting of GM crops at 125,000,000. Hectares this year if converted into acres it is 308,750,000, acres which is 5.15 times the total landmass of the United Kingdom. But to give a better example it is the combined landmasses of
France, Spain, Portugal, ROI and The Netherlands with a few acres to spare.
I appreciate that John Walker suggests we disregard this but I am at a loss as to why.
Every one of those acres will produce nearly double or more crop than those down to Organic production. By comparison with GM plantings Commercial Organic sowings pale into insignificance.
The Soil Association are fully convinced that Organics can alleviate the world of starvation. Well they are not really any good at producing food for the masses and I would suggest to you that their mathematical calculations are totally abysmal.
We have a growing world population and so many more mouths to feed that Commercial Organics could never hope to cope. Yet the Soil Association are still so dogmatic and blinkered that they cannot see the truth when it is right in front of their eyes.
GM is in its infancy and as the further generations of GM blossom ultimately Commercial Organics will be a thing of the past and only practiced by amateur gardeners.
It is for this reason that every time GM is mentioned in this country the Soil Association goes into a frenzy.
It is you The Soil Association that will disappear long before GM has reached its full potential.
JB.

I fully concur with Jb's above thoughts.

For me it is nothing to do with being anti organic growing methods but more to do with reality in a finite world.

Some of my comments regarding the Soil Association may have seemed harsh to some but they arise from frustration at what appears to be their complete self interest in promoting their 'creed' and instantly condemning any other points of view.

Again, I find much to recommend organic growing but do not exclude other advances in agriculture such as GM.

Barney

Good morning Soil Association

Well it's another week and your silence speaks volumes.

In your last, unhelpful, response you complained:

A quick point about our level of participation however is that we will not always be able to respond as frequently or in as much detail as we would like. As a charity we do not have the time nor resources to address every point raised on every forum on the net – wish that we did!

The following is quoted from your website:

Today the Soil Association is the UK's leading organic organisation, with over 200 staff based in Bristol and Edinburgh and working as certification inspectors across the country. The Soil Association's director is Patrick Holden, who reports to the Council of Trustees.

Or is it that David Shaw's authoritative post removes all credibility from your position on GM potatoes?

alan refail wrote:Good morning Soil Association

Well it's another week and your silence speaks volumes.

And another week passes

If you read the new magazine you will find they have been concentrating their efforts on checking if weed competition affects growth. Startling revelation is that young seedlings don't like competition. I've often accused them of bad science but this is just using resources to conclude the blindingly obvious.

Hi Geoff,
It seems that their time might have been better spent studying Cisgenic
Genetic modifications.

This extract is from Wikipedia Protoplast Biology:

While conventional transgenic plants are developed by introduction of a gene originating from distant, sexually incompatible species into the host genome, cisgenic plants contain genes which have been isolated either directly from the host species or from sexually compatible species. The new genes are however introduced using recombinant DNA methods and gene transfer. Principally the same result could be obtained by classical breeding. However the disadvantage of classical breeding is that with one desired trait also a number of undesired traits are transferred and the number of backcrosses necessary to remove these undesired traits approaches infinity. Some scientists hope that the approval process of cisgenic plants might be simpler than that of proper transgenics, but it remains to be seen.

You will note the bold type section talks of unwanted traits in conventional (classical) breeding programmes and the current GM trial, I presume, is to try and get around these unwanted traits as it seems difficult to get rid of them.
JB.

Geoff wrote:If you read the new magazine you will find they have been concentrating their efforts on checking if weed competition affects growth. Startling revelation is that young seedlings don't like competition. I've often accused them of bad science but this is just using resources to conclude the blindingly obvious.

Which magazine (and indeed which organisation) are you referring to?