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Operator exposure in the USThere were a number of presentations on sprayer contamination and operator exposure. Andrew Landers (Cornell University) commented on the situation in the USA where an estimated 560,000 establishments employ workers who come into contact with pesticides. While most operators have recognised the need for personal protective equipment, many have long resisted wearing it in hot and humid conditions. Landers conducted a survey on the current availability and use of engineering controls and found there were still many problems concerning the adoption and use of closed transfer systems. Dr Landers also conducted a survey of pesticide exposure levels on surfaces within sprayer cabs that was funded by the EPA. The highest chemical concentration levels were found on steering wheels and gauges, and in dust collected on fabric seats. Contamination of these areas could result in operator exposure to pesticides if the tractor is used for other farm purposes where the driver may not be using personal protective equipment. He concluded by saying that whilst tractor cab design has improved “in leaps and bounds over the past decade, many of the comments made about operator safety in the 1980s still apply today”. To encourage a faster adoption of protective measures may well require a ‘stick’ rather than ‘carrot’ approach. ECPA Safe Use InitiativeIn Europe, the European Crop Protection Association (ECPA) has introduced the “Safe Use Initiative”. Its objective is to stimulate the safe use of pesticides in Southern European countries through the introduction of novel, innovative spraying equipment and techniques and by teaching users how to handle, clean and maintain their equipment. ECPA and CLO-DVL, Ghent, Belgium (formerly known as the Research Station of Agricultural Engineering) joined forces to evaluate novel spray equipment with vertical spray booms for the application of crop protection products in greenhouses. When compared with the traditional spray gun both a manually pulled trolley and a self-propelled, motorised vehicle, the “Fumimatic”, achieved a better spray distribution on crops and may increase productivity and reduce labour costs. Additional research investigated the operator exposure from five different greenhouse spraying techniques commonly used in Southern Europe and demonstrated that there were very large differences in total body exposure between the different practices. Walking backwards using a spray lance rather than forwards reduced the exposure by a factor of seven while the use of the Fumimatic reduced exposure by a factor of 100 compared with a standard spay gun. Crop density & pesticide doseA number of presentations investigated adjusting pesticide dose to match crop density. Jerry Cross (HRI, East Malling) discussed “Pesticide dose Adjustment in relation to the Crop Environment” in UK apple orchards (PACE). The term PACE was coined in 1991 to describe systems which cut pesticide inputs in fruit production by reducing the product application rate to take account of various crop structure parameters. Using a Light Detection and Range (LIDAR) system to record crop structural details it had been possible to show that tree area density accounted for some 78% of the variation in average deposits. A pictograph key has been produced for tree area density so that the fruit grower can visually assess a “Crop Adjustment Factor” (CAF) and adjust the pesticide application rate accordingly. The biological efficacy of the PACE system has been evaluated in eight grower trials in commercial apple orchards. The trials confirmed that growers could assess the CAF with acceptable accuracy and obtain more uniform deposits. There is potential for large pesticide use savings and, according to Mr Cross, dose reductions can now form part of IPM programmes that include pest, disease and crop growth monitoring. Developments in vinesIn Italy the use of leaf-stripping in vines increases the presence of air within the row and is a widespread practice. The technique also limits the incidence of fungal diseases, in particular Botrytis cinerea, and increases exposure to sunlight, which colours the grape skins. According to Paolo Balsari, the University of Turin has been conducting trials to evaluate different types of leaf-stripping machines. The work demonstrates that it is possible to increase the amount of spray deposit and evenness of distribution. The results are encouraging as manual leaf-stripping is still very popular but extremely time consuming. Landers and Farooq (Cornell University) have investigated the factors influencing air and pesticide penetration in grapevine canopies. Current practice in the US is to use the same settings on an airblast sprayer in the vineyard from the first application through to the last, irrespective of changes in the canopy volume and density. A few growers may change application volume per hectare but not airflow or forward speed. The growers frequently drive too fast and often pay too little attention to deposition on the leaves and clusters of grapes where disease or insects may occur. Current practice in the early season is to utilise the vast amount of air generated to apply pesticides on alternate rows. The result is variable deposition, pollution and a considerable waste of power and money. Landers and Farooq looked at nozzle orientation, air volume and velocity and canopy density. They introduced novel developments to reduce airflow in an attempt to match air volume and speed with increasing crop canopy. The results have demonstrated the importance of correct nozzle orientation if pesticides are to be applied effectively to the target. Cereal fungicidesReducing spray application volumes is a popular way of increasing work rate. However, there is insufficient information available on the effect that this can have on crop protection. To fill the gap, experiments have been conducted with fungicides applied at T2 timing on winter wheat under the UK Sustainable Arable Link scheme. The results reported by Clare Butler Ellis (Silsoe Research Institute) indicated that application volume did not adversely affect performance, although the application method did. Application methods producing large droplets tended to give lower yields than those producing finer droplets. |