Maria Kuznetsova, head. Department, Department of Potato and Vegetable Crops Diseases, FGBNU VNII Phytopathologistsи
The situation around the world with the use of germination suppressants, in particular with chlorprofam, is gradually changing. In EU countries, following the publication of the European Food Safety Agency (EFSA) report on chlorprofam (CIPC), the use of this substance was forbidden.
In this regard, the question of reorienting potato storage facilities to other suppressants of germination arose. For example: in the UK, chlorprofam, according to AHDB (Agricultural and Horticultural Development Board), was used in more than 85% of all potato storage facilities. The ban on its use has come into force January 8 2020 years, the owners of storage facilities are faced with the need to clean potato storage from traces of this substance, and this is not an easy task.
A study organized by AHDB confirmed that concrete is permeable to CIPC: residual amounts of chlorprofam and its metabolite 3-chloraniline (3-CA) are fixed in all rooms where this germination suppressant was used, regardless of the concentration of the substance used and the number of treatments.
The Council for the Development of Agriculture and Horticulture has formulated the key principles that storage owners should be guided by when carrying out cleaning in order to reduce the risk of redistribution of chlorprofam in the potato storage, as well as to reduce the amount of phytopathogen inoculum:
- All storages in which chlorprofam was used must be cleaned in a timely manner, preferably immediately after the premises are cleared of the potato tubers of the previous year's harvest.
- Storage should be cleaned in compliance with the necessary safety measures: you need to use personal protective equipment and be careful when performing work at heights.
- It is necessary to keep a written registration of all cleaning activities carried out, accompanied by photographs (photographs should reflect what, how and when was cleaned). The potato buyer can request documents confirming the cleaning activities.
- Dry cleaning methods should be preferred. It is necessary to use water only in cases where dry cleaning is impossible or insufficient. With wet cleaning, it is necessary to remove excess water, avoiding environmental pollution.
- Cleaning activities should be carried out carefully, avoiding redistribution of chlorprofam. Loose items should be cleaned as quickly as possible, preferably using vacuum equipment. The use of brooms and brooms leads to the dispersion of dust, which contributes to the redistribution of traces of chlorprofam over the surfaces.
- Storage operations should be carried out from top to bottom (i.e. from roof to floor).
- Chlorprofam is a medium volatile compound, so if the store is not being used for storing potatoes, it is necessary to leave doors and hatches open to ventilate the room. Ventilation pipes must be well ventilated by ventilation or natural ventilation.
- Where possible, dry rubbish should be removed first, and then loose items should be removed to fresh air to allow sun (UV), rain, wind and temperature to remove chlorprofam.
- During cleaning, special attention should be paid to areas of high chlorprofam contamination.
Also, the European Potato Value Chain specialists have developed the “Guidelines for the implementation of measures for the cleaning of a storage facility in order to reduce its contamination with chlorprofam” in the form of infographics (Fig. 1).
But cleaning the premises is still not the main problem of the industry. The selection of a replacement for chlorprofam is much more difficult.
According to AHDB, at the moment in the UK it is allowed to apply as a suppressant of germination maleic acid hydrazide, peppermint oil and ethylene.
Recall that maleic acid hydrazide has been used as a suppressant in the UK since 1985 year. He it is used for the treatment of vegetative plants during the period of their active growth five weeks before desiccation or before the natural dying off of the tops. Maleic acid hydrazide inhibits cell division. It is absorbed by the leaves and redistributed to the tubers. In this case, the maximum amount of residual substances of maleic acid hydrazide in the final product should not exceed 50 mg / kg.
The effectiveness of the use of maleic acid hydrazide largely depends on the timeliness of treatment: too early use can reduce the volume of the crop, too late - will reduce the effectiveness of the suppressant application. Research has shown that maleic acid hydrazide best used for short-term storage of potatoes: the risk of sprouting in this case is low. Experts note that the treatment with maleic acid hydrazide, while maintaining the temperature in the storage at 7-10 ° C, made it possible to restrain the germination of potatoes intended for processing for 2-4 months.
Ethylene is actively used in the storage of table potatoes (at low temperatures, less than 5 ° C). But to maintain the quality of raw materials for processing, this suppressant is used less often: experts believe that it may cause discoloration of the flesh of potato chips when frying.
In order to slow down the germination of tubers in varieties going for processing, British experts recommend combining treatments with maleic acid hydrazide with treatments peppermint oil and ethylene. Although the search for the most effective technology for conducting combined treatments with suppressants is still ongoing.
The Council for the Development of Agriculture and Horticulture is active in outreach to help farmers find germination suppressants to replace chlorprofam.
In particular, a series of thematic webinars Storage Webinars has been launched, where experts talk about the features of alternative germination suppressants. In addition, the UK Storage Network provides free professional advice for potato growers who pay AHDB membership to develop a chlorprofam-free potato storage strategy.
In Russia, the use of chlorprofam has not yet been banned, but the situation may change, in which case Russian farmers will face more serious difficulties than British ones. According to the "Directory of pesticides and agrochemicals approved for use in the Russian Federation" for 2020, maleic acid hydrazide is approved for use in potato and vegetable stores, but the range of domestic drugs is much narrower than in the UK.
In general, it is important to understand that the use of suppressants in a potato storage facility can be minimized by adhering to the well-known principles of an integrated potato growing and storage system.