Legislation and Full Storages Prompt the Need for Alternative Sprout Inhibitors in Europe
The 2020 storage season is proving to be one of the most challenging ones for potato growers and store managers worldwide, but it is also the first when store managers in Europe cannot apply Chlorpropham (CIPC) to their potatoes in store.
The Maximum Residue Level (MRL) is the largest amount of a chemical residue that is allowed to be detected on a product, and in the case of CIPC, that MRL will have to be zero beginning October 8, 2020. According to specialists, the problem for existing potato storage sites is that CIPC gets into the (wooden) frames of the storage boxes, the air vents and other places, so residues can still be found long after the ban.
So, while everyone waits for the European Commission to publish temporary MRLs to regulate allowed residue after the deadline, store managers are faced with the tough decision to thoroughly clean their stores or risk not being allowed to use the same facilities for the next season.
Natural Dormancy Enhancer
But cleaning the stores is just the first step to a future trouble-free operation. The second, and most important step, is finding a suitable long-term replacement for CIPC.
PotatoBusiness.com reached out to specialized companies that offer alternative sprout-inhibiting treatments for potatoes, to help us paint a bigger picture of the different options available for store managers.
Dr. Bernhard Frings, CEO of DormFresh Ltd., a company that offers the 1.4SIGHT solution for the European market, says that a full ban of CIPC has always been on the horizon, maybe not expected in June 2019, but limitations to the product have always been a realistic option. He advises that all storages must be properly cleaned before any alternatives are considered.
1.4SIGHT is a dormancy enhancer that prolongs suppression in stored potatoes and is reversible. It is normally applied as a vapor (usually hot) to stored potatoes. 1.4SIGHT® penetrates through the potato skin and works internally to restore its dormancy, a process which lowers the respiration rate, slowing the loss of moisture and solids, thereby diminishing shrink and susceptibility to pressure bruise. Moreover, restoring dormancy may also shorten the post-harvest “sweat period”.
“A storage manager can use the same fogging machines as he has been using for CIPC. But he must understand the characteristics of 1.4SIGHT being a volatile product. It works not as an herbicide killing a meristem, but rather by keeping the potato <sleeping> through a natural mechanism.”
Therefore, an important point is that stores must be tight and ventilation timing must be adapted.
Frings also listed a few guidelines for a successful 1.4SIGHT application, but underlined that store managers should study all the parameters found in the comprehensive Technical Manual and work with company representatives on the best practices tailored for each particular case:
- Check the store on tightness;
- Use the right fogging equipment – such as ‘Electro Fogger’, but other hot fogging equipment can be used as well.
- Watch the quality of fog they produce and adjust if necessary – a good fog has a balanced particle size;
- The time of application should be planned as early as possible, as soon as the tubers are dry. Adapted ventilation management after use is also crucial to achieving the highest possible efficiency;
- Speed of application must be moderate and adjusted.
“It is important for increased efficiency that the tubers absorb the active ingredient immediately after application, in order to deepen the mechanism of dormancy. A sufficient closing time of the store is helpful and necessary for this. But even later, it is important to reduce ventilation with outside air to a minimum, to maintain a stable atmosphere with the active ingredient and to extend the influence.
As such, CO2 management should be reconsidered. Good tightness also helps to keep the product in stock and prevents the active ingredient from being lost to the outside,” Frings explained.
While the size of the store is not that crucial for the product performance, Frings warns that it is important to fill the warehouse with potatoes as much as possible, in order to minimize dilution effects due to empty space.
The Ethylene Solution
Dirk Garos, director of Restrain, a company that specializes in ethylene-based sprout suppressing systems, says that “the ban on CIPC and the uncertainty of the regulations on the tMRL for CIPC made farmers hesitant to apply more of the same product. Restrain identified the need for support in this crisis and offered free ethylene generators for the current 1,5 million ton stocks, to keep these sprout-free and avoid any CIPC residue surplus.”
Restrain is a system that uses natural ethylene gas, which keeps potatoes dormant and prevents sprouting. Using ethylene gas means there won’t be any residue left in the crop or in the storage facility, allowing the immediate delivery of potatoes for processing.
The system works in all bulk stores, box stores or even ‘leaky’ stores. Ethylene being a dynamic gas that has about same weight as air, within minutes it is evenly distributed throughout the space.
“The maximum capacity of one Restrain generator is about 5000 tons, depending on the leakiness of the store,” Garos explains.
Restrain supplies the equipment with the ethylene sensor built in, with additional sensors for measuring and recording CO2, humidity, temperature and consumption of ethanol. The software on the Restrain equipment is pre-programmed with the ideal ethylene concentrations, according to the manufacturer.
“We have developed a dedicated protocol for processing potatoes. Before customers switch on the ethylene application, we first check on the potato activity (respiration) when the potatoes are cooled down below 10°C. The test consists of simply switching on the Restrain generator without ethanol and recording data for one week – temperature, CO2, humidity,” Garos describes.
The aim of the tests is to monitor the CO2 levels, and to always keep them at a concentration below 2500 parts per million (ppm). The reason being that high CO2 levels, in combination with ethylene, can, in some cases, adversely affect the frying texture and color of the processing potatoes.
Garos also points out that the ethylene solution can work equally well in leaky stores or half-empty ones, except that it will be less economical, since the generators will be working to meet the target concentration in both cases.
Nick Tapp is the director of Juno Plant Protection, a company that has been distributing spearmint oil as a sprout inhibitor for the UK potato market for the last eight years. He told PotatoBusiness.com that his product, marketed under the name Biox-M, is also a viable and safe replacement for CIPC.
Biox-M has no harvest interval, as crops treated with it may be removed from store immediately. However, he advises that there should be a retention period of up to 12 days in store, to allow the naturally occurring odor to dissipate.
According to Tapp, spearmint oil is highly effective in the control of sprouting in stored potatoes. Moreover, Biox-M has worked well with all varieties treated to date, with normal variety dormancy remaining unchanged, while very dormant varieties taking longer to recommence sprouting.
Lastly, Tapp says that Biox-M is approved for use on organic crops, and is suitable for use in multi-purpose stores. Crops treated with Biox-M have reduced weight loss in store and, unlike CIPC, it leaves no residue in buildings and boxes.
The Way Forward
With most of the new crop potatoes already planted, there is little time left for store managers to consider an economic alternative to CIPC. This is especially important taking into account the cleaning procedures they will undoubtedly have to perform, so that they can use their facilities next season.
Now that the COVID-19 restrictions are beginning to be lifted in much of Europe, the consumption of potato products can only increase, which will surely kick-start the whole transition process for everyone involved.