Over the past 20 years it has become increasingly apparent that our heritage potatoes are deteriorating (far smaller crops from each potato planted with far more evidence of disease and pest issues), and since the introduction of the psyllid, (which brings a host of damaging viruses) the problem has dramatically worsened.
In the 2011 harvest season we harvested marbles 1-2cm diameter. We were unable to eat anything or sell the seed at this point. This was our national potato collection so it was a very serious situation.
On top of the pest and disease issue, or part of the reason for these issues, is the fact that our New Zealand soils are also now seriously de-mineralised. Just as we humans can not maintain our health or the integrity of our DNA over generations if we do not feed our body well, the potatoes are not able to maintain the genetic strength they began with if we do not feed them the minerals from the rich soils they evolved with.
It is many years since serious selection work has been done by home gardeners maintaining these lines, although in recent times there are several groups beginning that process again including Joseph Land’s work in the Hokianga where he grows a range of the Koanga Institute seed potatoes. Until now the Koanga Institute has not been in a position to improve our entire collection, our resources have simply been overstretched.
Since arriving here in Kotare Road we have decided it is the time to go for it and we have had a lot of support to do this job as explained later in this report.
Other people and organisations in NZ who hold serious potato collections (including industry growers) are endeavouring to get their collections cleaned up by ‘tissue culture’ in the lab, which is a way of taking the viruses out of the potatoes and beginning again with virus free seed potatoes. This is a costly process for each variety, and we do not believe this will strengthen the genetics of the potatoes. We have seen a kumara collection lost in this way, and the tissue cultured plants are vulnerable to all the viruses and psyllids that continue to exist in the environment, when they are planted again in the real world.
Here at the Koanga Institute, we believe that we must find an alternative solution, one that can be followed by home gardeners in New Zealand to strengthen and maintain the integrity of the plant’s DNA. The science of epigenetics has taught us that
ENVIRONMENT DETERMINES GENETIC EXPRESSION
In this instance, this means that if we are able to supply all the required nutrients to the plants, and create a strong and healthy soil (environment) full of beneficial microbiology and minerals, then the strongest plants will adapt and survive…. and we can select from these to maintain the lines.
Our Potato Project this year (2012 harvest season), was supported by Environmental Fertilisers, who have designed a biological nutrient program, including solid and liquid fertilisers, and we followed their advice, adjusting things as required.
The fertiliser program is as follows:-
1. Soak potatoes in compost tea for 12 hours then place in a bag with Koanga: Seedling Innoculant and shake to lightly cover potatoes with innoculant.
2. Prepare your potato trenches and apply to each metre of trench: 400 gms of EF:Nature’s Garden, (fertilser mix containing a wide range of nutrients balanced according to the principles of Dr Carey Reams) 200 gms of EF:Nano-Cal (lime that has been composted with a carbon source to hold the calcium in the root zone), 200 gms of Biochar.
3. Plant potatoes, cover them, then water with liquid Bio char
4. Last 3 foliar sprays before harvest, add EF:Manganese chelate which will strengthen the quality of the seed. Manganese is the element of life that gives seeds their strength!
We planted a trial plot of 200sq m, which means that we were able to plant approx 20 plants of each cultivar in our collection.
With the help of a 1935 NZ Department of Agriculture Potato Growers booklet (142!) we kept a careful eye on each potato plant as they emerged and rogued (removed) almost all (couldn’t bear to remove everything then, that would mean losing a line!) plants that appeared with crinkly leaves and or yellow blotches on the leaves. We also removed all plants that looked spindly and weak, compared to others. Some cultivars were noticeably weaker than others and we decided not to remove all plants where an entire line looked weak We rogued the entire patch 3 times in the first 3 months of growth, finally just before flowers opened.
Once the flowers were open there was a marked increase in insect activity, with the insects potentially become disease vectors… so the aim of the rogueing is to remove all diseased plants before the insects come in and spread the disease.
We used our Koanga BioPesticide (entirely composed of beneficial microbes and fungi) to keep psyllids to a minimum and are very excited about the potential of this new product.
We also received information from Scott Lawson showing that a trial in the USA showed that erecting a black shade cloth fence around the potato patch works to keep out over 90% of psyllids as well.
We used our refractometer to test regularly before and after spraying to make sure we were actually doing what the plants needed, and we raised the brix of the potatoes to around 14 which is relatively high for potatoes.
At harvest we dug each plant separately, and weighed the tubers from each plant.
We selected our mother seed from the best tubers from the best producing plants from each cultivar, from the plants left after the rogueing .
We also photographed each variety for the website so you can all see what we have!