Potato Stores in Great Britain - The Food and Environment Research ...

PESTICIDE USAGE SURVEY REPORT 174
POTATO STORES
IN GREAT BRITAIN
2000
H. H. Dennison, D. G. Garthwaite & M. R. Thomas
Pesticide Usage Survey Group
Central Science Laboratory
Sand Hutton
York UK
YO41 1LZ
Department for Environment, Food & Rural Affairs
&
Scottish Executive Environment & Rural Affairs Department

CONTENTS PAGE
Definitions iii
Summary 1
Introduction 2
Methods 4
Results and discussion
Ware potatoes 6
Tables 8
Seed potatoes 12
Tables 13
Comparison with previous surveys in Great Britain 15
Acknowledgements 20
References 20
Appendix 21
ii

DEFINITIONS
a) 'Applications' is used throughout this report to refer to the number of pesticide treatments applied to a store
(whole or part).
b) 'Basic tonnes treated' is the gross weight of potatoes treated with pesticides excluding repeat applications, i.e.
the total tonnes stored minus tonnes receiving no treatment.
c) 'Tonnage treated' is the gross weight of potatoes treated with pesticides including repeat applications, i.e. basic
tonnes treated x number of applications.
d) ‘Bulk stores’ include loose potatoes in a variety of stores, as opposed to those stored in boxes or bags.
e) ‘Outdoor clamps’ include potatoes stored in the field in a temporary structure. These structures are often
constructed from straw bales or soil.
f) ‘Unventilated stores’ include structures which are naturally ventilated and rely on convective ventilation.
g) ‘Ventilated stores’ include structures using forced air ventilation. They do not use refrigeration methods.
h) ‘Refrigerated stores’ include structures using refrigeration; they may also have forced air ventilation.
i) ′Merchant′ is a BPC registered purchaser, a merchant or processor who has traded 100 tonnes of potatoes or
more in the most recent full crop year and therefore qualifies for payment of British Potato Council levy (British
Potato Council List of Registered Purchasers July 2001).
j) ′Farm Store′ holds only potatoes from a single holding, where the store is located, for a period of more than 2
months.
k) In this report the term ‘formulation(s)’ is used to describe the pesticide active substance or mixture of active
substances in a product(s).
l) ‘Seed potatoes’ are those stored and used for planting the next season’s crop. Prior to planting, seed potatoes
are placed in a ‘chitting house’ where the tuber can develop/germinate prior to planting.
m) “Ware potatoes” are those used for human consumption, either prior to or after processing.
n) The ‘Advisory Committee on Pesticides’ is a statutory body set up by ministers under section 16(7) of the Food
& Environment Protection Act 1985 to advise on all matters relating to the control of pesticides. For further
information visit the website – www.pesticides.gov.uk/committees/acp/acp.htm
o) ‘Arable crops’ include cereals, combinable peas & beans, oilseed rape, linseed, potatoes and sugar beet.
QUALITY CONTROL OF DATA
All field data are collected by personal interview using fully qualified staff working to standard operating procedures.
Supplementary postal data are collected from merchant stores with storeowners completing standard forms to set
operating procedures. Paper records are held at Sand Hutton, but individual holdings cannot be identified. Data are
entered onto a computer database which has extensive error checking routines associated with the input program. Each
item of data is then checked after entry and subsequently all forms are re-checked by someone other than the original
operator. Prior to compilation of the tables, the data are further subjected to a range of computer checks to detect,
amongst other things, any values, which, on agronomic grounds, appear suspect. Any thus revealed are further
scrutinised, and, if necessary, referred back to the original source. All the tables are prepared by computer once the data
set is considered correct, thus eliminating transcription and typographical errors.
iii

SUMMARY
This report presents information on all aspects of pesticide usage during storage of potatoes harvested in 2000 and stored
during 2000/01. Data were collected from visits to 90 holdings in Great Britain and by post from 104 merchants.
The total weight of ware potatoes stored from the 2000 harvest was 4.09 million tonnes, of which this survey estimated
that 49% received no treatment. The basic tonnage treated was 2.08 million tonnes, though some potatoes received
multiple treatments. The active substance chlorpropham, a potato sprout suppressant, accounted for 85% of the total
tonnage treated, while 4.6% were treated with pyrethrins, 3% with tecnazene and 2% with thiabendazole. There were 61
tonnes of active substances used to treat ware potatoes. Chlorpropham (82%), tecnazene (14%), and thiabendazole (4%)
accounted for nearly all of the weight of active substances used.
From this survey, it is estimated that 20% of the 428,700 tonnes of seed potatoes stored were treated, generally receiving
one application. The main formulations used were imazalil, dichlorophen and 2-aminobutane accounting for 94%, 3%
and 2% of the total tonnage treated respectively. Just over one tonne of active substances were used, principally imazalil
(61% of the total weight), and 2-aminobutane (29%).
A comparison is made between this survey and a similar one conducted in 1998. The tonnage of ware potatoes stored
was just under 2% more in the most recent survey, but the total tonnage treated was 14% less. The tonnage of ware
potatoes treated with chlorpropham decreased by 9% and this was used on 85% of the total tonnage treated. The weight
of active substances applied to ware potatoes decreased by 41%. Ninety four percent of all applications to ware potatoes
were made by fumigation. This was also the preferred application method in 1998.
The tonnage of stored seed potatoes in Great Britain increased by 19% between the two surveys and the basic tonnage
treated decreased by 48%. Overall, there was a 78% decrease in the amount of active substances used on seed potatoes.
1

INTRODUCTION
The independent Advisory Committee on Pesticides advises the British Government on all aspects of pesticide use. In
order to discharge this function the Committee must regularly monitor the usage of all pesticides in Great Britain. It
needs accurate data on the usage of individual pesticides.
As part of the ongoing process for obtaining data, the Pesticide Usage Survey Teams of the Central Science Laboratory,
an executive agency of The Department for Environment, Food & Rural Affairs (DEFRA) and the Scottish Agricultural
Science Agency, an agency of the Scottish Executive Environment Rural Affairs Department (SEERAD), conducted a
survey of pesticide usage in potato stores on farms in Great Britain growing potatoes harvested in 2000. However, visits
to holdings had to be curtailed in February of 2001 because of the potential risks involved resulting from the Foot and
Mouth outbreak. Limited visits were resumed in the autumn of 2001 to a smaller sample of holdings than would
normally have been visited in previous years. Information was also collected from potato merchants, who stored potatoes
over the same period of time, using a postal questionnaire.
This is the fifth fully co-ordinated survey of pesticide usage at potato stores in Great Britain. The previous reports
covered all pesticide usage on potatoes harvested and stored in 1992 (Olney & Garthwaite, 1992), 1994 (Goodwin &
Garthwaite, 1994) 1996 (De’Ath et al., 1996) and in 1998 (Fox et al., 1998). One previous report has covered pesticide
usage in England and Wales for potatoes harvested and stored in 1988 and 1990 (Olney et al., 1992). Two previous
reports have covered pesticide usage at potato stores in Scotland (Tucker, 1978, Snowden et al., 1989) for potatoes
harvested and stored in 1975 and 1986 respectively. In 1974 and 1977 information was collected on pesticide usage at
farm stores in Great Britain but was reported in an unraised format covering usage only on those farms surveyed
(Chapman et al., 1977, Steed et al., 1979).
A list of the most recently published reports can be found in the Appendix.
2

Fig 1. Counties in DEFRA regions of England and Wales and regions covered by the SEERAD Scotland
Midlands & Western
Cheshire
Derbyshire
Greater Manchester
Hereford & Worcester
Lancashire
Leicestershire
Merseyside
Nottinghamshire
Shropshire
Staffordshire
Warwickshire
West Midlands
Wales
Clwyd
Dyfed
Gwent
Gwynedd
Mid Glamorgan
Powys
South Glamorgan
West Glamorgan
South Western
Avon
Cornwall
Devon
Dorset
Gloucestershire
Somerset
Wiltshire
Scotland
Borders
Central
Dumfries & Galloway
Fife
Grampian
Highlands & Islands
Lothian
Strathclyde
Tayside
3
Northern
Cumbria
Cleveland
Durham
Humberside
Northumberland
North Yorkshire
South Yorkshire
Tyne & Wear
West Yorkshire
South Eastern
Berkshire
Buckinghamshire
East Sussex
Greater London (SE)
Hampshire
Kent
Oxfordshire
Surrey
West Sussex
Eastern
Bedfordshire
Cambridgeshire
Essex
Hertfordshire
Greater London (E)
Lincolnshire
Norfolk
Northamptonshire
Suffolk

METHODS
The sample
The samples of holdings to be surveyed were selected using data from the Agricultural Census Returns, June 1999 for
England and Wales (Anon., 2000a) and for Scotland (Anon., 2000b).
The samples were drawn to represent the area of all arable crops grown throughout England, Wales and Scotland. For
England and Wales, the sample was selected within each of the six old MAFF regions (Fig. 1), while Scotland was
divided into 11 land-use regions (Wood, 1931). The samples were stratified according to the total area of all arable crops
grown in each region and by holding size group based on the total area of arable crops grown on each holding. The area
of arable crops sampled in each size group and each region was proportional to the total area of arable crops grown on
holdings of each size group in each region.
An introductory letter was sent to the occupiers of the selected holdings explaining the purpose of the survey. A total of
825 arable holdings was visited and information relating to potato storage was obtained from those growing potatoes. Of
the 181 holdings growing potatoes, 90 (50%) stored them after harvest (Table 1). Holdings selling potatoes on to
merchants were asked for details of these stores. Further information on these stores, and on additional storage premises,
was provided by the British Potato Council (BPC). Data relating to pesticide usage on these premises were obtained by
postal questionnaire at a later date.
Data were raised to estimate national pesticide usage (Thomas, 2001). The raising factors used for ware potatoes were
based on a combination of census data (Anon 2001a, Anon 2001b) and potato stock movement information provided by
the BPC. Separate raising factors were used for seed potatoes, which were also based on BPC estimates for stored seed
potatoes in Great Britain.
Table 1 Number and distribution of stores sampled in Great Britain - 2000
Region
Farm Stores Merchant Stores
Eastern 34 27
Midlands & Western 8 9
Northern 10 15
Scotland 25 45
South Eastern 6 3
South Western 5 5
Wales 2 .
Total – all regions 90 104
4

METHODS (continued)
The Questionnaire
The questionnaire consisted of two forms, which were completed by an experienced surveyor during an interview with
the farmer, or by a store representative following issue of a comprehensive set of instructions, for commercial stores.
Form 1 summarised the area of potatoes grown on each holding during the 2000 growing season.
Form 2 detailed all aspects of pesticide usage in each store. A separate form was completed for each method of storage
and treatment programme. Seed and ware potatoes were recorded separately and identical forms were sent to merchants
as part of a postal survey.
TONNAGE OF POTATOES STORED
It is estimated that 144,702 hectares of ware potatoes and 16,800 hectares of seed potatoes were grown in 2000 in Great
Britain. An estimated 3,059,198 tonnes of ware potatoes were stored in farm stores and 1,029,301 tonnes were stored by
merchants (Table 2). An estimated 428,700 tonnes of seed potatoes were stored in Great Britain.
5

RESULTS AND DISCUSSION
WARE POTATOES
Storage type
The three main types of stores on farm were ventilated (54%), refrigerated (34%) and unventilated (12%). A small
quantity, (

substances (a.s.) were used on stored ware potatoes, comprising of 50.2 tonnes of chlorpropham (82%), 8.5 tonnes of
tecnazene (14%) and 2.2 tonnes of thiabendazole (4%).
In farm stores chlorpropham (89%) was the main storage treatment used, 6% of the total tonnage was treated with
propham and 6% with pyrethrins. Forty-one tonnes of active substances were used, with chlorpropham accounting for
86% and tecnazene 11%. Thiabendazole, imazalil, pyrethrins and propham accounted for the remainder of the weight of
active substances used.
At merchant stores chlorpropham was used on 90% of the total tonnage treated, with thiabendazole on 4% and tecnazene
on 3%. Merchant stored potatoes were treated with approximately 21 tonnes of active substances. Chlorpropham
accounted for the majority of active substances applied, at 73%, with tecnazene at 19% and thiabendazole at 7%.
Stated reasons for treatment
The main reason given for pesticide usage at farm stores, with 99% of the total tonnage treated (where a reason was
given), was to suppress sprouting (Table 6). Chlorpropham accounted for 89% of sprout suppressant usage. Imazalil was
applied to 99% of the potatoes treated for disease control.
The most important reason given for pesticide applications at merchants’ stores was for sprout suppression (96% where a
reason was given), with 4% specifying disease control (Table 7). Chlorpropham was the most widely used sprout
suppressant accounting for 96% of all pesticide applications, with tecnazene used on just 3%. There was only a limited
use of pyrethrins recorded, presumably for the control of flies in store.
Methods of application
The methods of application used on farms included thermal fogs (95%), granules (3%) and sprays (2%) (Table 8). The
only granules applied were tecnazene formulations. The majority of spray applications comprised of thiabendazole (58%)
and imazalil (42%). No dusts were used on ware potatoes at farm stores.
Table 9 shows that 92% of all application methods at merchant’s stores were thermal fogs, with chlorpropham
accounting for 97% of the total tonnage treated in this manner. Only four percent of applications were sprays and most of
these (89%) comprised thiabendazole alone. Granular applications were made to 4% of merchant stored potatoes, with
79% being tecnazene formulations. The only dusts used were tecnazene based.
7

8
Table 2 Storage methods used for ware potatoes at farm and merchant stores in Great Britain, 2000 (tonnes stored)
Outdoor Unventilated Ventilated Refrigerated Total Total -all
Clamp 1 Bulk Box Bulk Box Bulk Box Bulk Box methods
Farm stores 23,648 301,372 55,277 1,151,293 490,268 166,813 870,528 1,643,125 1,416,073 3,059,198
Merchant stores . 12,069 14,018 163,391 397,231 32,307 410,286 207,766 821,535 1,029,301
All stores 23,648 313,441 69,295 1,314,684 887,499 199,120 1,280,814 1,850,891 2,237,608 4,088,499
1 By definition outdoor clamps are bulk storage

9
Table 3 Farm Potato Stores: Storage pesticide use on ware potatoes in Great Britain, 2000 (tonnes treated)
Outdoor Unventilated Ventilated Refrigerated Total Total -all
Clamp 1 Bulk Box Bulk Box Bulk Box Bulk Box methods
Pesticide
Chlorpropham 17,880 206,428 . 671,991 409,854 105,642 580,725 1,001,940 990,578 1,992,518
Chlorpropham/propham . . . 149,660 . . . 149,660 . 149,660
Imazalil . . . . 11,116 . 14,419 . 25,536 25,536
Pyrethrins . . . 40,374 57,677 . 49,026 40,374 106,703 147,077
Tecnazene . 17,618 12,193 3,445 36,345 . . 21,063 48,539 69,602
Thiabendazole . . . . . . 34,606 . 34,606 34,606
Total - all pesticides 17,880 224,046 12,193 865,469 514,992 105,642 678,776 1,213,037 1,205,962 2,418,999
Not treated 11,535 180,540 43,083 612,070 226,640 72,707 481,581 876,852 751,304 1,628,156
Table 4 Merchants’ Potato Stores: Storage pesticide use on ware potatoes in Great Britain, 2000 (tonnes treated)
Unventilated Ventilated Refrigerated Total Total -all
Bulk Box Bulk Box Bulk Box Bulk Box methods
Pesticide
Chlorpropham 10,305 4,642 165,758 291,430 69,627 394,398 245,690 690,470 936,160
Imazalil . . . 811 . 3,713 . 4,525 4,525
Pyrethrins . . . . . 10,723 . 10,723 10,723
Tecnazene 2,477 186 13,368 12,811 . 3,713 15,845 16,710 32,555
Thiabendazole . . 33,421 . . 4,085 33,421 4,085 37,506
Unspecified potato sprout suppressants 1,300 5,570 . 6,499 . . 1,300 12,069 13,369
Total - all pesticides 14,081 10,398 212,548 311,551 69,627 416,632 296,256 738,581 1,034,837
Not treated 464 3,621 16,200 136,476 12,811 214,789 29,475 354,885 384,360
1 By definition outdoor clamps are bulk storage

Table 5 Usage of individual active substances on stored ware potatoes in Great Britain, 2000
Farm stores Merchant stores Total
Tonnes Tonnes Tonnes Tonnes Tonnes Tonnes
treated (a.s) treated (a.s) treated (a.s)
Pesticide
Chlorpropham 2,142,179 34.94 936,160 15.26 3,078,338 50.19
Imazalil 25,536 0.21 4,525 0.04 30,061 0.25
Propham 149,660 0.18 . . 149,660 0.18
Pyrethrins 147,077 < 0.01 10,723 < 0.01 157,800 < 0.01
Tecnazene 69,601 4.54 32,556 3.97 102,157 8.51
Thiabendazole 34,606 0.7 37,506 1.5 72,112 2.2
Unspecified potato sprout suppressants . . 13,368 . 13,368 .
Total 1 – all pesticides 2,418,999 40.56 1,034,837 20.8 3,453,836 61.36
Table 6 Farm Potato Stores: Storage pesticides and their reason for use on ware potatoes in Great Britain, 2000
Sprout Disease Sprout supp. & Unspecified Total Active
suppressant control disease control reason tonnes substance
treated (tonnes)
Pesticide
Chlorpropham 1,427,231 . . 565,287 1,992,519 33.77
Chlorpropham/propham 149,660 . . . 149,660 1.35
Imazalil . 14,419 . 11,116 25,536 0.21
Pyrethrins . . . 147,077 147,077 < 0.01
Tecnazene 22,366 . 202 47,033 69,601 4.54
Thiabendazole . . . 34,606 34,606 0.7
Total – all pesticides 1,599,257 14,419 202 805,120 2,418,999 40.56
Table 7 Merchants’ Potato Stores: Storage pesticides and their reason for use on ware potatoes in Great Britain, 2000
Sprout Disease Sprout supp. & Unspecified Total Active
suppressant control disease control reason tonnes substance
treated (tonnes)
Pesticide
Chlorpropham 907,763 . . 28,397 936,160 15.26
Imazalil . 1,485 2,228 811 4,525 0.04
Pyrethrins . . . 10,723 10,723 < 0.01
Tecnazene 26,365 . 2,477 3,713 32,556 3.97
Thiabendazole . 37,506 . . 37,506 1.5
Unspecified potato sprout suppressants 7,798 . . 5,570 13,368 .
Total – all pesticides 941,927 38,991 4,705 49,214 1,034,837 20.8
1 Denotes the total tonnage treated, not the column sum as entries are not always mutually exclusive.
10

Table 8 Farm Potato Stores: Formulations of storage pesticides used on ware potatoes in Great Britain, 2000 (tonnes treated)
Thermal fog Granule Spray Total
Pesticide
Chlorpropham 1,992,519 . . 1,992,519
Chlorpropham/propham 149,660 . . 149,660
Imazalil . . 25,536 25,536
Pyrethrins 147,077 . . 147,077
Tecnazene . 69,601 . 69,601
Thiabendazole . . 34,606 34,606
Total – all pesticides 2,289,256 69,601 60,142 2,418,999
Table 9 Merchants’ Potato Stores: Formulations of storage pesticides used on ware potatoes in Great Britain,2000 (tonnes treated)
Dust Thermal fog Granule Spray Total
Pesticide
Chlorpropham . 928,001 8,158 . 936,160
Imazalil . . . 4,525 4,525
Pyrethrins . 10,723 . . 10,723
Tecnazene 2,663 . 29,893 . 32,556
Thiabendazole . . . 37,506 37,506
Unspecified potato sprout suppressant . 13,368 . . 13,368
Total – all pesticides 2,663 952,092 38,052 42,030 1,034,837
11

SEED POTATOES
RESULTS AND DISCUSSION
Storage type
An estimated 428,700 tonnes of seed potatoes were stored in Great Britain (Table 10). The majority of potatoes were
stored in ventilated environments (63%), refrigerated stores accounted for a further 37%, unventilated storage being least
common, accounting for less than 1%. All of the seed potatoes were stored in boxes.
Treatment of potatoes
Overall, 20% of potatoes were treated, receiving on average a single pesticide application (Table 10 & 11). The main
products employed were imazalil (94%), 2-aminobutane (3%) and dichlorophen (2%). Boxed potatoes in ventilated
stores accounted for 66% of the total tonnage treated, principally with imazalil (92%).
Extent and quantity of individual active substances used
Use of four active substances was encountered on seed potatoes (Table 12). Imazalil was used to treat the majority
(94%) of the tonnage treated. Less than 2 tonnes of active substances were applied, imazalil accounting for 61% and 2aminobutane
29%, with the remainder being dichlorophen and tecnazene.
Stated reasons for treatment
Table 13 shows that the only reason specified for pesticide usage was disease control. Imazalil alone was used on 94%
of the treated tonnage where a reason was specified. Dichlorophen and 2-aminobutane accounted for a further 6% and
4%, respectively, of the tonnage treated where a reason was specified.
Methods of application
Sprays accounted for 94% of the formulations used to treat seed potatoes held in store, fumigation 5% and granules the
remaining one percent. The only formulation applied as a spray was imazalil. Two fumigant formulations were recorded
2-aminobutane and dichlorophen. All granules were tecnazene-based formulations.
N.B. All treatments to seed potatoes refer to storage treatments and do not include pre-planting seed treatments or
treatments in chitting houses. Information on potato seed treatments can be found in the arable crops report for 2000
(Garthwaite & Thomas, 2002).
12

13
Table 10 Storage methods used for seed potatoes in Great Britain, 2000 (tonnes stored)
Unventilated Ventilated Refrigerated Total Total -all
Bulk Box Bulk Box Bulk Box Bulk Box methods
All regions . 1,038 . 270,651 . 157,011 . 428,700 428,700
Table 11 Storage pesticide use on seed potatoes in Great Britain, 2000 (tonnes treated)
Unventilated Ventilated Refrigerated Total Total -all
Bulk Box Bulk Box Bulk Box Bulk Box methods
Pesticide
2-aminobutane . . . 2,376 . . . 2,376 2,376
Dichlorophen . . . 2,001 . . . 2,001 2,001
Imazalil . . . 52,005 . 28,010 . 80,015 80,015
Tecnazene . . . . . 750 . 750 750
Total . . . 56,381 . 28,760 . 85,142 85,142
Not treated . 1,038 . 214,270 . 128,251 . 343,558 343,558

Tabe 12 Usage of individual active substances on stored seed potatoes in Great Britain, 2000
Total tones treated 1
Active substance (tonnes)
Pesticide
2-aminobutane 2,376 0.35
Dichlorophen 2,001 0.02
Imazalil 80,015 0.72
Tecnazene 750 0.09
Total – all pesticides 85,142 1.19
Table 13 Storage pesticides and their reason for use on seed potatoes at stores in Great Britain, 2000
Disease Unspecified Total tonnes Active substance
control reason treated (tonnes)
Pesticide
2-aminobutane 1,250 1,125 2,376 0.35
Dichlorophen 2,001 . 2,001 0.02
Imazalil 32,437 47,578 80,015 0.72
Tecnazene . 750 750 0.09
Total – all pesticides 35,688 49,454 85,142 1.19
Table 14 Formulations of storage pesticides used on seed potatoes in Great Britain, 2000 (tonnes treated)
Granules Fumigant Spray Total
Pesticide
2-aminobutane . 2,376 . 2,376
Dichlorophen . 2,001 . 2,001
Imazalil . . 80,015 80,015
Tecnazene 750 . . 750
Total – all pesticides 750 4,377 80,015 85,142
1 Denotes the total tonnage treated, not the column sum as entries are not always mutually exclusive.
14

COMPARISON BETWEEN SURVEYS CARRIED OUT IN GREAT BRITAIN IN 1994, 1996, 1998 & 2000
In 2000, it was estimated that the tonnage of ware potatoes harvested was 6,207,600 tonnes with a yield averaging 40.1
tonnes/hectare. The area of ware potatoes grown has increased by nearly 2% since the last survey while the area of seed
potatoes grown has increased by 3%. There has been an increase of just under 2% in the tonnage of ware potatoes stored
and an increase of 19% in the tonnage of seed potatoes stored (Table 15).
WARE POTATOES
Storage type
There has been an 8% reduction in the tonnage of ware potatoes being stored in farm facilities since 1998. In 2000 and
1998, ventilated stores were the principal type used, with an increase from 40% in 1998 to 54% of ware potatoes stored
in this manner on farms. This increase is in contrast to the downward shift observed since 1994, when 62% were stored
in ventilated stores, to 51% in 1996 and 40% in 1998. Unventilated farm stores decreased from 24% in 1998 to 12% in
2000, while the proportion of refrigerated stores remained similar at 36% in 1998 and 34% in 2000. In the current survey,
46% of ware potatoes stored on farms were stored in boxes, whilst in 1998 the figure was 57%. In 1994 bulk storage was
most common but the proportion of potatoes stored by this method has decreased from 62% in 1994, to 43% in 1998,
increasing to 54% in 2000.
The tonnage of ware potatoes stored by merchants increased by 47% between 1998 and 2000. Ventilated stores were the
most common store type in 2000 (54%), increasing from 38% of the total in both 1996 and 1998. Previously,
refrigerated stores had been the most important accounting for 58% in 1996, 55% in 1998, decreasing to 43% in 2000.
Unventilated stores decreased from 7% in 1998 to 3% in the current survey. The majority (80%) of merchant stored
potatoes were stored in boxes in both 1998 and 2000, declining from 87% of the total in 1996.
Treatment of potatoes at farm stores
The percentage of potatoes treated with either sprout suppressants or against storage diseases has decreased since the last
survey, with 47% of potatoes held in farm stores being treated in 2000, 55% in 1998 and 45% in 1996. This is greatly
reduced from the 1994 survey, where 70% of potatoes were treated and reflects the increased use of refrigeration and the
approaching withdrawal of tecnazene formulations. There was a 52% decrease in the total tonnage of active substances
used in farm stores between 1998 and 2000, following the trend of a 14% decrease between 1996 and 1998. This was
mainly due to a decrease in the use of tecnazene and the increased application of chlorpropham, an active substance used
at considerably lower rates when compared to tecnazene. Overall, the use of chlorpropham increased from 39% of all
tonnage treated in 1996 to 80% in 1998 and to 83% in 2000. The use of formulations containing tecnazene decreased
from 34% of the treated tonnage at farm stores used in 1996, to 10% in 1998 only 3% in 2000. The use of
tecnazene/thiabendazole formulations was not recorded in 2000.
There has been a reduction in the number of formulations used on bulk-stored potatoes from seven formulations in 1996,
to five in 1998 and four in 2000. The number of formulations used on boxed potatoes was six in 1996, four in 1998 with
five formulations being found in the current survey. The use of 2-aminobutane was not encountered on either boxed or
bulk stored ware potatoes in 2000.
15

Treatment of potatoes at merchant stores
The proportion of potatoes treated in merchant’s stores was 63%. This was an increase since the previous survey in 1998,
which estimated 50% were treated. In 1996 and 1994, 68% and 87% of merchant stored potatoes were treated,
respectively. The number of applications made to potatoes in store decreased to 1.7, although there was a 4.8% increase
in the tonnes of active substances used since the previous survey. The proportion of bulk-stored potatoes treated
decreased since the last survey from 86% to 57%, and the average number of treatments fell from 2.7 to 1.7. The average
number of treatments on box-stored potatoes also decreased from 2.5 to 1.6.
Chlorpropham remained the most important active substance used on all merchant-stored potatoes, increasing from 79%
of the total treated merchant-stored potatoes in 1996 to 82% in 1998 and to 90% in 2000. Seventy-four percent of these
treatments were applied to box-stored potatoes, showing an increase of 7% since 1998.
The trends in treatments to ware potatoes in the UK since 1994 are shown in Figure 2 below and in Table 15.
Fig. 2 Treatments made to ware potatoes in Great Britain, 1994 to 2000
Million tonnes
7
6
5
4
3
2
1
0
Extent and quantity of active substances used
The current survey recorded the use of tecnazene on only 3% of all potatoes stored on the farm and in merchant’s stores.
This contrasts with the predominant use of tecnazene recorded in all previous surveys.
There was an overall reduction of 41% in the weight of active substances applied to ware potatoes between 1998 and
2000, following a downward trend, with a 15% decrease having been recorded between 1996 and 1998. The
accumulated decrease between 1994 and 2000 is 72%. The weight of chlorpropham applied remained similar to that of
1998, while the weight of tecnazene applied decreased further by 80% and the weight of thiabendazole applied also
decreased by 78% between 1998 and 2000.
Stated reasons for treatment
1994 1996 1998 2000
Tonnes stored Basic tonnes treated Total tonnage treated
Tonnes untreated Tonnes of active substance
16
250
200
150
100
50
0
Tonnes (active substance)

In 1994, 1996 and in 1998, the main reason for treating stored ware potatoes was to suppress sprouting. This remains the
main reason given and chlorpropham continues to be the major active substance used, as in all previous surveys.
Methods of application
Thermal fogs have remained the preferred method of application for farm and merchant stored potatoes. This was also
the situation in 1994, 1996 and 1998.
Since 1996, tecnazene has been the only dust formulation used in farm stores. In 1994, tecnazene dust formulations were
used in combination with thiabendazole or carbendazim. Tecnazene was also the only substance applied as a granule on
ware potatoes in 1996 and 1998, whilst in 1994 chlorpropham granules were also used. The current survey found
tecnazene and chlorpropham to be the only granular formulation used in merchant stores, with tecnazene the only granule
formulation used in farm stores.
17

SEED POTATOES
Storage type
The total tonnage of stored seed potatoes increased by 19% over the period between the previous and current surveys.
The proportion stored in ventilated stores decreased slightly from 64% in 1998 to 63% in 2000. Refrigerated storage
increased during the same period from 24% in 1998 to 37% in 1998. All seed potatoes encountered in 2000 were stored
in boxes, an increase from 90% in 1998.
Treatment of potatoes
The proportion of the tonnage treated was found to have decreased between 1998 and 2000 by 28%, following an
increase from 33% in 1996 to 46% in 1998. In 2000 imazalil accounted for 94% of the total tonnage treated, 2aminobutane
3%, dichlorophen 2% and tecnazene the remaining 1%. In 1998, imazalil accounted for 72%, imazalil/
thiabendazole, 15% and 2-aminobutane 12% of the tonnage treated. In 1996, imazalil and 2-aminobutane were used to
treat 53% and 40% of stored seed potatoes. Iprodione was used on 3% in 1996; but this formulation was not recorded on
stored seed in the current survey.
The trends in treatments to seed potatoes in the UK since 1994 are shown in Figure 3 below and in Table 15.
Fig. 3 Treatments made to seed potatoes in Great Britain, 1994 to 2000
Thousand tonnes
450
400
350
300
250
200
150
100
50
0
1994 1996 1998 2000
Tonnes stored Basic tonnes treated Total tonnage treated
Tonnes untreated Tonnes active substance
18
18
16
14
12
10
8
6
4
2
0
Tonnes (active substance)

Stated reasons for treatment
In 2000, the only reason that treatment was given was to prevent disease, as in 1998, 1996 and 1994.
Methods of application
Following the trend observed in the previous two surveys, spray applications as a percentage of the treated tonnage have
continued to increase from 59% in 1996 to 94% in 2000. Two fumigant formulations were found in the current survey,
2-aminobutane and dichlorophen, each accounting for approximately half of the total tonnes treated by this method. The
only fumigant applied in both 1998 and 1996 was 2-aminobutane, possibly indicating a move away from 2-aminobutane
in favour of dichlorophen. Granules accounted for less than 1% of treatments in 1996, 1998 and 2000.
Table 15 Comparison of production, storage and treatment of potatoes in Great Britain 1992-2000
1994 1996 1998 2000
Area grown (ha) Ware 140,346 152,776 142,119 144,702
Seed 14,505 15,718 16,263 16,800
Tonnes stored Ware 4,358,332 4,190,647 4,011,278 4,088,499
Seed 366,675 353,615 360,611 428,700
Basic tonnes treated 1 Ware 3,176,820 2,042,725 2,169,300 2,075,983
Seed 127,819 117,788 164,366 85,142
Total tonnage treated 2 Ware 6,128,118 3,562,785 4,019,982 3,453,836
Seed 134,622 121,902 164,336 85,142
Tonnes untreated 3 Ware 1,181,512 2,147,922 1,841,978 2,012,517
Seed 238,856 235,827 196,245 343,558
Tonnes treated 4 with Chlorpropham 4,296,254 2,149,132 3,232,223 3,078,338
(ware + seed) Tecnazene 769,756 806,400 371,104 102,157
Thiabendazole 982,480 610,290 253,029 72,112
Amount used (tonnes a.s.) Chlorpropham 90.88 28.58 49.09 50.19
(ware + seed) Tecnazene 77.29 70.68 43.31 8.6
Thiabendazole 45.75 23.04 10.21 2.2
1 Basic tonnes treated = tonnes stored – tonnes untreated
2 Total tonnage treated = basic tonnes treated x number of treatments
All pesticides 236.46 133.84 109.98 62.55
3 Tonnes untreated = potatoes stored which receive NO pesticide treatments during storage
4 Tonnes treated = basic tonnes treated x number of treatments
19

ACKNOWLEDGEMENTS
Thanks are due to all the growers and merchants who participated in this survey, providing the information upon which
this report is based. Many thanks are also due to John Kerr, Jeremy Snowden and Louis Thomas for organising the
collection of Scottish data. The work of Julie Bankes, Aimee Dawson, Fiona Hutson, Emma Maidment, Gillian Parish,
Lynda Smith and Harley Stoddart is gratefully acknowledged. Thanks also go to the members of the Working Party on
Pesticide Usage Surveys for their invaluable comments.
REFERENCES
Anon. (2001a) Agricultural Statistics in England and Wales 1999. London: HMSO.
Anon. (2001b) Agricultural Statistics, Scotland 1999. Edinburgh: HMSO.
Anon. (2000a) Agricultural Statistics in England and Wales 1999. London: HMSO.
Anon. (2000b) Agricultural Statistics, Scotland 1999. Edinburgh: HMSO.
Chapman, P. J., Sly, J. M. A., Tucker, G. G. & Cutler, J. R. (1977) Pesticide Usage Survey Report 11 - Arable farm
crops 1974. London: DEFRA.
De’ath, A., Garthwaite, D. G., & Thomas, M. R. (1996) Pesticide Usage Survey Report 145 - Potato stores in Great
Britain 1996. London: DEFRA/SEERAD
Fox, E., Garthwaite, D. G., & Thomas, M. R. (1998) Pesticide Usage Survey Report 161 - Potato stores in Great
Britain 1996. London: DEFRA/SEERAD
Garthwaite, D. G. & Thomas, M. R. (1999) Pesticide Usage Survey Report 159 – Arable Farm Crops in Great Britain
1998. London: DEFRA/SEERAD
Garthwaite, D. G. & Thomas, M. R. (2002) Pesticide Usage Survey Report 171 – Arable Farm Crops in Great Britain
2000. (in press)
Goodwin, L. B. & Garthwaite, D. G. (1996) Pesticide Usage Survey Report 129 – Potato stores in Great Britain 1994.
London. DEFRA.
Olney, N. J., Garthwaite, D. G. & Cotterill, N. D. (1992) Pesticide Usage Survey Report 92 - Potato stores in England
& Wales 1988 & 1990. London: DEFRA.
Olney, N. J. & Garthwaite, D. G. (1994) Pesticide Usage Survey Report 114 - Potato stores in Great Britain 1992.
London: DEFRA.
Snowden, J. P., Bowen, H. M. & Dickson, J. M. (1989) Pesticide Usage Survey Report 73 - Potato in store 1986-87.
Edinburgh: SEERAD.
Steed, J. M., Sly, J. M. A., Tucker, G. G. & Cutler, J. R. (1979) Pesticide Usage Survey Report 18 - Arable farm
crops 1977. London: DEFRA.
Thomas, M.R. (2001) Pesticide usage monitoring in the United Kingdom. Annals of Occupational Hygiene, 45
(supplement 1): S87-S93.
Tucker, G. G. (1978) Survey of pesticide usage on potatoes stored from the 1975 crop. The Seed Potato, 18, No 1, pp 17
- 22.
20

PESTICIDE USAGE SURVEY REPORTS APPENDIX
Surveys which include data relating to Scotland are marked with *
Surveys which include data relating to Northern Ireland are marked with #
PUBLISHED REPORTS
125 Rodenticide usage by Local Authorities in Great Britain 1993/94* PB 2786 £4.00
126 Aerial applications, Great Britain 1994* PB 2262 £7.00
127 Arable farm crops in Great Britain 1994* PB 2409 £4.00
128 Soft fruit in Great Britain 1994* PB 2787 £4.00
129 Potato stores in Great Britain 1994* PB 2788 £4.00
130 Rodenticide usage on farms in Great Britain growing arable crops 1994* PB 2789 £4.00
131 Forestry, Northern Ireland 1993 # ISBN 1855272822
132 Arable crops, Northern Ireland 1994 # ISBN 1855273144
133 Aerial applications, Great Britain 1995* PB 2790 £4.00
134 Outdoor vegetable crops in Great Britain 1995* PB 2944 £4.00
135 Mushrooms in Great Britain 1995* PB 3341 £4.00
136 Protected crops (edible and ornamental) in Great Britain 1995 PB 3293 £4.00
137 Farm grain stores in Great Britain 1994/95* PB 2946 £4.00
138 Commercial grain stores in Great Britain 1994/95* PB 3522 £3.00
139 Vegetable crops, Northern Ireland 1995 # ISBN 1855273462
140 Mushroom crops, Northern Ireland 1995 # ISBN 1855273470
141 Arable farm crops in Great Britain 1996* PB 3330 £6.00
142 Orchards and fruit stores in Great Britain 1996* PB 3698 £4.00
143 Hops 1996 PB 3801 £2.00
144 Rodenticide usage on farms in Great Britain growing arable crops 1996* PB 4243 £2.00
145 Potato stores in Great Britain 1996* PB 4187 £2.00
148 Aerial applications, Great Britain 1996* PB 3699 £3.00
149 Aerial applications, United Kingdom 1997* # PB 3802 £2.00
150 Review of usage of pesticides in agriculture & horticulture throughout Great Britain 1986-1996* PB 4188 £2.00
151 Grassland & fodder crops in Great Britain 1997* PB 4189 £3.00
152 Hardy Nursery Stock in Great Britain 1997* PB 4280 £3.00
153 Outdoor bulbs & flowers in Great Britain 1997* PB 4244 £2.00
154 Rodenticide usage on farms in Great Britain growing grassland and fodder crops 1997* PB 4739 £2.00
155 Rodenticide usage by Local Authorities in Great Britain 1997* PB 5411 £3.00
158 Aerial applications, Great Britain 1998* PB 4552 £3.00
159 Arable farm crops in Great Britain 1998* PB 4808 £4.50
160 Soft fruit in Great Britain 1998* PB 5412 £3.50
161 Potato stores in Great Britain 1998* PB 5413 £2.50
164 Protected crops (edible and ornamental) in Great Britain 1999* PB 6166 £3.50
165 Mushroom crops in Great Britain 1999* PB 6167 £1.00
172 Orchards and fruit stores in Great Britain 2000* PB 6168 £1.50
173 Hops in Great Britain 2000 PB 6169 £1.00
179 Farm grain stores in Great Britain 1998/99* PB 6170 £1.00
180 Commercial grain stores in Great Britain 1998/99* PB 6171 £1.00
Copies of reports categorised PB may be purchased from DEFRA Publications, London SE99 7TP (01645 556000).
Copies of reports categorised ISBN may be obtained through Her Majesty’s Stationary Office.
21