Executive summary - Potato Stores
This report presents information from a survey of pesticide use in Scottish potato stores on tubers harvested in 2016. Data were collected from 65 growers, who collectively cultivated 25 per cent of the area of potatoes grown in Scotland. Pesticide use in potato stores was recorded for crops grown for seed production and for consumption (ware potatoes). Ratio raising was used to produce estimates of national pesticide usage from the sample data.
The overall estimated quantity of potatoes stored in 2016 was 1,140,286 tonnes, which was very similar to that reported in 2014. Both the 2016 and 2014 storage estimates were almost 20 per cent greater than 2012 which was a climatically difficult year for Scottish potato production.
Sixty one per cent of seed and 77 per cent of ware potatoes were stored in refrigerated stores in 2016. The majority of the remaining stores were ambient ventilated stores. Over 99 per cent of potatoes were stored in boxes.
The proportion of stored seed and ware potatoes receiving an in-store pesticide treatment in 2016 was 47 and 11 per cent respectively. These proportions are the same as reported in 2014.
As in 2014, the principal formulation used on seed potatoes in 2016 was the fungicide formulation imazalil/thiabendazole, which was applied to an estimated 27 per cent of the stored crop for control of a range of tuber diseases. The only other fungicide applied was imazalil, to 19 per cent. As in 2014, a small proportion of the seed crop was treated with ethylene (one per cent). Ethylene is approved as a commodity substance for plant growth regulation in post-harvest crops under the Control of Pesticides regulations ( COPR).
As in the last survey, chlorpropham, a growth regulator used for sprout suppression, was the most commonly used formulation on ware potatoes, applied to seventeen per cent of tubers stored in 2016. Ethylene, the principal sprout suppressant formulation for ware potatoes prior to 2014, was applied to one per cent of the crop. The fungicidal formulations, imazalil and imazalil/thiabendazole were both applied to less than 0.5 per cent of the stored ware crop.