What’s in store for potatoes?

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By Gemma Carroll, Communications & Engagement Officer PNZ 

Food for thought for New Zealand’s potato sector, as the EPA embarks on reviewing and revising the list of approved chemicals for horticultural groups. 

There will always be a focus on safety, when it comes to chemicals applied to our food and so the current EPA process is welcomed, as we strive to provide the best product for the consumer. 

If we find ourselves at some stage, in the same position as our UK counterparts, with a non-renewal of a sprout suppressant, what should we be looking at now as alternatives, to play the vital role in potato storage?  

In New Zealand we are perhaps fortunate to have approved registration for Dimethylnapthalene (DMN). This naturally occurring compound is also a by-product of the petrochemical industry. 

British researchers first found it in potatoes and potato stores in the 1980s, it was seen to decrease in concentration, as storage time lengthened, indicating potatoes could contain their own sprout suppressant (DMN). When DMN was applied to potato stores, excellent sprout suppression was achieved and so a new storage product was developed.  

So what is the U.K. industry facing? 

The U.K is likely to lose CIPC sprout suppressant, but AHDB are investigating alternatives and solutions, including researching varieties with longer dormancies. 

In a recent article in www.potatonewstoday.com, Lukie Pieterse wrote the following: 

CIPC is used as a sprout suppressant on more than 80 per cent of potatoes stored in the UK, however the future of CIPC remains uncertain as the European Food Safety Agency’s recommendation is for non-renewal, which could leave many growers lacking options in terms of short and long term potato storage. (AHDB Potatoes) 

While CIPC remains the most effective method for reducing sprouting in storage, AHDB has been carrying out trials on alternative suppressants and early results have shown that some of these options work well, particularly when combined. This latest research builds on previous work on sprout suppression which has been recognised as a major issue due to the industry’s reliance on CIPC. 

Uncertain future 
AHDB crop storage senior scientist Adrian Briddon explains: “It looks likely that in the future, growers won’t be able to rely on one active product, but instead may need to combine two or three chemicals, such as maleic hydrazide and DMN, to get the same result. 

For example in the first year of trials, combinations of active substances were needed to control sprouting in the most demanding conditions, without CIPC.    

Maleic hydrazide, a growth regulator also used for sprout suppression was recently re-approved for use, but with changes to its label that may reduce the extent of its use in some markets.  

DMN is effective in both pre-pack and processing stores; and is of particular interest because in the USA it is also registered for use on seed. So, as well as sprout control for ware potatoes, there may also be interest in using it to modify stem and progeny tuber numbers. 

The article is further supported by information on AHDB’s related strand of varietal dormancy research, on their website https://ahdb.org.uk/ 

The dormancy characteristics of 30 or so potato varieties are currently being monitored at AHDB’s Sutton Bridge stores, to assess which remain dormant longest and so which offer growers the greatest chance of reducing chemical inputs and costs. 

“Although our understanding of potato dormancy is incomplete,” Adrian explains, “we know that some varieties will remain dormant for a short period, perhaps just a few days, whereas others will do so for months. This work will give us a better understanding of which commercially popular varieties can last longest in store without sprout suppressant being applied. 

“If we can identify varieties with reliable, long periods of dormancy, the industry has the option to reduce their use of sprout suppressants by growing varieties that are better suited to growers’ stores.” 

The research into alternative options to CIPC will run for two more seasons with the aim of providing growers with alternative sprout suppressant strategies as chemical use is further restricted. 

Here is what the future may hold for the U.K.  

At our upcoming conference in August, we have 2 experts in potato storage presenting their advice and taking attendees through a workshop on their storage capabilities and needs. 

Allan Greenhalgh from TOLSMA and Chris Thorman from EIT, will provide international and domestic viewpoints, for the consideration of our industry.