It’s no secret why potato sprout inhibiting CIPC is so popular: it’s cheap and it works. That said, the EU’s recent banning of CIPC has caused many North American producers to proactively ask about alternatives. Here’s what’s available to tackle sprouting today.
Scientists and companies continue to tinker with ethylene. The work isn’t new: we’ve seen industry trying to make sprout control via ethylene commercially viable for 20-plus years. The main problem that hasn’t been solved yet is potatoes removed from an ethylene environment really, really want to grow. For that reason, ethylene doesn’t work at all well for table stock and is only minimally successful with chipping and processing potatoes.
Essential oils can be effective at tackling sprouting, though they are burn agents rather than sprout inhibitors. Clove oil is on the United States’ Grass 40 list, making it acceptable for American organic production. Here at home, clove oil has not been approved for use, primarily because our very small organic potato industry doesn’t have the capacity to get the product through PMRA’s stringent approval process.
Several rescue products exist, some of which can achieve up to 98 per cent burn back. That said, I always remind farmers that being ahead of one’s tubers is much, much better than trying to catch up. Once a potato hits a certain physiological age, it’s really hard to hold them back, no matter how effective the product you use. Also, it’s worth noting that some rescue products are currently banned in the EU.
The very best sprout inhibiting alternative currently available is 1,4-DMN (1,4-Dimethylnaphthalen): a biochemical which triggers hormones that slow tuber maturation. Unlike CIPC, which is applied as a dust and must contact the tuber eye, DMN goes on as an easy-to-apply vapour and can be absorbed by any part of the tuber. Fully reversable and naturally occurring, DMN can be used on seed potatoes and carries no soil or storage contamination concerns.
DMN is more volatile the CIPC, which means that it does need to be applied several times throughout the storage season. That said, DMN offers a handful of value-added benefits that offset its higher effort and input cost. In addition to effectively controlling sprouting, DMN triggers fungistatic genes: especially important now that disease promoting, higher-than-normal spring and fall temperatures are increasingly common in many potato growing and storing regions.
DMN also triggers a gene that prevents tubers from losing water during storage. Farmers sometimes forget that they’re not getting paid per potato; they’re getting paid by weight and quality. In certain regions, we regularly see piles drop as much as three feet over the storage season. Getting better recovery out of storage — together with better quality achieved through less shrink — is a huge and immediate return to farmers.