SUMMARY This report presents information from a survey of pesticide usage practices on mushroom crops in Northern Ireland in 2007. It is the fourth survey of pesticide usage practices conducted on the mushroom sector in the region. Data were collected from 52 growers, representing 95% of all mushroom holdings in Northern Ireland. Compared with the previous survey in 1999, the number of growers decreased by 81% with the basic cropping area decreasing by 73% to approximately 10 hectares (ha).
The quantity of pesticides used decreased accordingly by 86% and the area treated with pesticides decreased by 79% between 1999 and 2007. A total of 554 kilograms of pesticides and 4.8 tonnes of disinfectant chemicals were applied to 135 and 100 spray hectares of mushroom production houses, respectively. In common with previous surveys, fungicides applied to 40% of the pesticide-treated area accounted for the majority (91%) of the weight of pesticides used. The fungicide active ingredient prochloraz was the most extensively used pesticide overall, applied to 35% of the pesticide-treated area and 89% of the fungicide-treated area. Applications of insecticides were applied principally to the interior walls and structure of the mushroom houses prior to crop production. The active ingredient bendiocarb accounted for 91% of insecticide usage. The only biological control agent recorded in this survey was the insect-pathogenic nematode Steinernema feltiae. Disinfectants usage on yard areas outside the mushroom houses and as part of the house sterilisation process decreased by 22% in area compared with 1999. However, the quantity of disinfectants used increased by 25%, principally due to the high concentration of chlorine active ingredient in some products. A total of 18 products, comprising seven pesticide active ingredients, four disinfectant active ingredients and one biological control agent were recorded in this survey.
DEFINITIONS AND NOTES • ‘Cropping area’ refers to the basic cropping area. (Example A: if a single mushroom house was filled with 800 blocks @ 0.24m2 per block, the cropping area = 192m2 per house )
• ‘Area grown’ refers to the basic area multiplied by cropping periods completed. (Example B: if the house in example A was filled on 6 occasions during the year 192m2 X 6 = 1152m2 the total area grown).
• ‘Fills / filling’ refers to the first stage of the mushroom production cycle where the compost is put into the house. There are multiple fills of compost per year, with the number dependent on the mushroom cycle period length that is influenced by the growing method.
• ‘Flushes’ refers to the number of crops taking off a single fill of compost, normally three crops.
• ‘Casing’ is a layer of peat mixed usually with sugar beet lime applied to the surface of the compost after the mycelium has permeated the compost, to encourage formation of the mushroom fruit bodies.
• ‘End spray’ At the end of the mushroom cycle, if there is a disease / pest present, a pesticide or disinfectant may be applied to the spent compost prior to disposal.
1 INTRODUCTION As a participant in the UK Working Party on Pesticide Usage Surveys, the Agri-Food and Biosciences Institute (AFBI) on behalf of the Department of Agriculture and Rural Development for Northern Ireland (DARDNI), conducts a programme of surveys to examine pesticide usage in all sectors of the agricultural and horticultural industries. Principally, the data collected provides information for consideration by the Advisory Committee on Pesticides. In addition, the information may also be used by those involved in residue testing, for public information and to evaluate the impact of policy and trends in pesticide usage.
This is the fourth survey of pesticide usage on mushroom production in Northern Ireland. Results from the previous surveys reported on pesticide usage practices on mushroom production in 1991 (Kidd et al., 1994), 1995 (Kidd et al., 1998) and 1999 (Kearns et al., 2002) are included in the report for comparative purposes. The report includes both pesticide and disinfectant usage. A list of published Northern Ireland Pesticide Usage Survey reports is shown in Appendix 1.
THE MUSHROOM INDUSTRY IN NORTHERN IRELAND The mushroom industry in Northern Ireland has experienced substantial changes in recent years. The number of growers has reduced from 289 in 1999 to 55 in 2007. The basic cropping area decreased by 73% when compared to 1999 and 60% when compared with 1991. However, total mushroom production in Northern Ireland in 2007 was estimated at 19,000 tonnes with a value of £21.7million, representing a similar output level to 1991 and an overall 24% decrease compared with 1999 (Anon., 2008).
The maintenance of mushroom production outputs despite a reduction in the number of growers suggests an increase in unit production size and efficiency of crop production. In addition cultivation methods have also changed since 1999. In 2007 the traditional ‘bag-system’ accounted for 14% of houses producing mushrooms, with 21% of growers using this system compared with 97% of growers in 1999. The ‘bag-system’, which uses plastic bags filled with Phase II compost has been virtually replaced by a similar system of production using rectangular compost blocks with a larger surface area than bags (0.24m2 compared with 0.15m2) or a loose compost system on shelves.
Approximately 50% of all mushroom houses recorded in this survey (48% of growers) employed the block system. A minority of growers (8%) used a combination of both blocks and bags.
The loose compost system on shelves involves the use of Phase II or Phase III compost filled directly onto shelves. The advantage of the shelf system is that compost-filling and casing are normally carried out simultaneously. Where Phase III compost is used, mycelium has fully colonised the compost, therefore reducing the production cycle and allowing for more production cycles per house per year. Approximately 36% of all production houses and 23% of growers used the loose compost system on shelves in 2007.
The mushroom cycle is determined by the types of compost and production system used. Typical examples of Phase II and Phase III compost systems are outlined below.
Phase II • Compost supplied normally in blocks or bags direct from the supplier.
• Casing added 10 to 16 days later.
• First mushroom flush from day 26 to 31.
• Second mushroom flush approximately seven days later.
• Third mushroom flush seven days later.
• House emptied.
Phase III • Compost and casing supplied loose on the same day.
• First mushroom flush 16 days later.
• Second mushroom flush approximately seven days later.
• Third mushroom flush seven days later.
• House emptied.
White cap mushrooms are most commonly grown, accounting for 343 production houses. An estimated 61 production houses produced brown mushrooms.
METHODS Using a list supplied by the Department of Agriculture Northern Ireland (DARDNI) and commercial suppliers lists the population of mushroom growers were established and selected. A preliminary letter was sent to growers explaining the purpose of the survey. Of a possible population of 55 growers, 52 holdings participated in the survey. The data has been raised to give estimates of regional pesticide usage. Growers were visited during September 2007 and data relating to pesticide usage were collected by personal interview. This survey covers the period from October 2006 to September 2007.
The data collected included; the number and area of mushroom houses, method of production, number of crops per annum, type of treatment, area and number of times treated and the production stage at application. The grower’s stated reasons for pesticide use were also included, but may not always seem appropriate. The sampled data was raised to the population and the collected data were analysed using SPSS software.
RESULTS AND DISCUSSION Regional Pesticide Usage Of the 55 mushroom growers in the population, 53% were in County Armagh representing 46% of the basic area of mushroom crops grown. A further 29% of growers were in County Tyrone accounting for 31% of the area grown (Table 1; Figures 1 and 2). Conversely, growers in County Tyrone accounted for 39% (32% in County Armagh) of the total pesticide-treated area. An estimated 46% of all fungicide and 38% of insecticide treatments were applied in this county (Table 2).
Pesticide Usage in Mushroom Production The estimated area treated and weight of pesticides used at each stage of mushroom production are shown in Tables 3 (Figure 3) and 4, respectively. More than half (54%) of pesticide applications occurred from casing to first flush, accounting for 45% of the quantity of active ingredients used. Fungicides accounted for 40% of the pesticide-treated area and 91% of the weight of pesticides applied. An estimated 67% of fungicides were applied between casing and first flush, accounting for 44% of the quantity of fungicides used. While the end of cropping spray accounted for only 9% of fungicide applications it represented 40% of the total weight of fungicides applied.
Insecticides accounted for 36% of the pesticide-treated area and 9% of the weight of pesticides applied. The majority (89%) of insecticide treatments were applied at the house sterilisation stage before compost was delivered. Casing to first flush accounted for 54% of the weight of insecticides applied and 9% of the insecticide treated area. Biological controls were applied to 24 % of the total pesticide-treated area in 2007, compared with 4% in 1999. Total Pesticide Usage An estimated 0.5 tonnes of pesticide active ingredients were applied to 135 spray hectares of mushroom crops in Northern Ireland in 2007 (Tables 3 & 4).
The active ingredients (including biological control agents) recorded in the survey, ranked by application area and quantity applied are listed in Tables 5 & 6.
Two fungicide active ingredients were recorded in this survey. Formaldehyde, applied principally as an end of cropping spray, to eliminate any potential diseases prior to disposal of the spent compost, represented 11% of the fungicide-treated area and 47% of the weight of fungicides applied. Prochloraz applied between casing and first flush, and between first and second flush accounted for 89% of the fungicide-treated area and 53% of the weight of fungicide active ingredients. The application of prochloraz post casing is not approved, making this a mis-use.
Five insecticide active ingredients were recorded. Bendiocarb, applied to the interior structure of the mushroom houses prior to ‘filling’, was the most frequently used active ingredient, applied to 91% of the insecticide-treated area and accounting for 45% of the weight of pesticides applied. The only biological control agent recorded was the insect-pathogenic nematode Steinernema feltiae, used on approximately 33 spray hectares of mushroom crops after casing and before first flush to control flies (Tables 7 & 8). PESTICIDE USAGE ON MUSHROOM PRODUCTION STAGES (Table 9) House sterilisation These treatments require the use of pesticides / disinfectants, applied to the interior structure of the mushroom house when the house is empty. Dependent upon the grower’s production system this may include applications to racks/shelves/nets etc.. Insecticide paints may be applied to the interior walls. Pesticides applied to mushroom houses prior to ‘filling’ represented 33% of the total pesticide-treated area, but only 10% of the total quantity of active ingredients applied (Tables 7 & 8). The fungicide formaldehyde applied as a ‘disinfectant’ for general hygiene and the insecticide bendiocarb, applied to the interior walls of the mushroom houses, were the two active ingredients recorded in use at this stage. Pre-casing When the house is filled with bags /blocks an insecticide may be applied to control flies prior to casing. Pesticides applied at the pre-casing stage accounted for less than 1% of both the total pesticide-treated area and quantity of pesticides applied (Tables 7 & 8). The only active ingredient recorded in use was the insecticide bendiocarb, to control flies. Between casing and first flush An estimated 54% of all pesticide applications were undertaken at the post-casing stage, accounting for 45% of the total quantity of pesticides used (Tables 7 &8). Approximately 67% of all fungicides applied during mushroom production were applied at this stage, representing 44% of the quantity used. The only fungicide active ingredient recorded used at this stage was prochloraz, with 50% of applications to control wet and dry bubble (Mycogone and Verticillium). Insecticides applied post-casing accounted for only 9% of the total insecticide applications, but 54% of the quantity of insecticides used. Diflubenzuron was the most extensively used insecticide, accounting for 84% of the insecticide-treated area and 99% of the quantity used. The biological control agent, Steinernema feltiae, was recorded in use post-casing to control flies and accounted for 24% of the pesticide-treated area at this stage. Between First and Second Flush Pesticides applied between the first and second flush accounted for 9% of both the total pesticide-treated area and the quantity of pesticides applied (Tables 7 & 8). Fungicides accounted for 96% of all pesticides applied at this stage. Prochloraz, applied principally to control bubble was the only fungicide recorded. Bendiocarb and the formulation of pyrethrins/resmethrin were the insecticides applied at this stage, principally to control sciarid flies. No pesticides were applied between the second and third flush. End Spray Atthe end of the crop production cycle. If disease / pests are present, the grower may apply a treatment prior to disposal. Pesticides applied to ‘spent’ compost at the end of crop production to prevent the release of airborne spores accounted for 4% of the total pesticide-treated area and 36% of the total quantity of pesticides applied (Tables 7 & 8). The fungicide formaldehyde and the insecticide malathion were the active ingredients recorded in use at this stage. Spawn-running houses Mushroom ‘spawn’ is a culture of Agaricus bisporus mycelium that is added to the compost. Generally growers buy in compost that has been spawn-run. However, some growers spawn-run their own compost and dedicate houses, usually on units separate from the production unit to this procedure. Of the 52 growers surveyed five spawnrun their own compost, accounting for 27 houses in total.
Houses dedicated to spawn-running accounted for 3% of all pesticide and disinfectant applications to mushroom houses and less than 1% of quantity of pesticide used. Disinfectants were the principal treatments applied to 89% of the treated area, with insecticides accounting for the remaining 11% of applications (Table 10). PESTICIDE USAGE AND GROWING METHODS An estimated 43% of all pesticides were applied to production houses using loose compost on shelves, 41% to those using blocks, 9% to those using bags, 7% to houses that combined bags and blocks and 1% to spawn-running houses. A distribution of pesticide usage across growing methods is shown in Tables 11 and 12.
DISINFECTANT USAGE ON HOUSE AND YARD AREAS Disinfectants are extensively used to maintain general hygiene levels in both the mushroom production houses and the yard areas surrounding the houses. An estimated 58% of all disinfectants were applied to the yard areas with the remaining 42% of applications to the house structure and equipment (i.e. shelves, nets etc.).Disinfection applied after the houses were emptied accounted for 92% of both the total disinfectant-treated area and quantity of disinfectants used in mushroom production houses, the remaining 8% of disinfectants were applied to ‘spent compost’ prior to disposal. Phenolic derivatives were applied to 51% of the treated yard area, 19% of the quantity of disinfectants applied. Chlorine applied to 3% of the disinfectant-treated area accounted for 37% of the quantity of disinfectants used on yards (Tables 13 & 14). The horticultural bactericide sodium hypochlorite was also recorded used on both the yard and production house areas.
COMPARISON WITH PREVIOUS SURVEYS OF PESTICIDE AND DISINFECTANT USAGE IN MUSHROOM PRODUCTION (Tables 15 to 19) The population of mushroom growers decreased by 81% in 2007 compared with 1999, with a consequent (73%) decrease in basic cropping area and 62% decrease in the overall area grown. In common with previous surveys, the majority of pesticides were applied between casing and first flush. The principal stage of disinfectant application was also comparable with previous years, with treatments predominantly applied at house sterilisation. However, unlike in the previous surveys, no disinfectants were recorded applied between casing and first flush or between flushes in 2007.
The use of biological controls is continuing to increase, with a 29% increase in 2007 compared with 1999. The only biological control agent recorded was S. feltiae, used principally between casing and first flush.
The disinfectant-treated area decreased by 22%. However, the overall quantity of disinfectant used increased by 25% compared with that recorded in 1999. The decrease in disinfectant usage approximated to the decrease in mushroom houses.
However the increase in quantity used is partly due to the increased use of chlorine. Disinfectants, applied to the yard area surrounding the houses, increased three-fold by comparison with 1999, suggesting an increased awareness of preventative hygiene in this area, possibly influenced by the increasing use of loose compost.
ACKNOWLEDGEMENTS The authors wish to thank all of the growers who participated in the survey. The assistance of Mrs Trudyann Kelly on analysis of the data was invaluable. Thanks also to Mr John Anderson for his assistance during data collection. We are particularly grateful to Ms Mairead Kilpatrick and staff in the Mushroom Section at the Northern Ireland Horticultural and Plant Breeding Station Loughgall for their invaluable advice on mushroom agronomy, Mr Cathal Ellis (DARDNI Food Development Service) and Mr Brendan Burns, Sylvan Ireland for their contribution to the compilation of the population list.
