Potato Review

26 POTATO REVIEW NOVEMBER/DECEMBER 2020 FUNGICIDE TREATMENTS e importance of even crop ow for accurate treatment is one of the reasons against on-harvester application, where it is impossible to control. Calibration in three simple steps e three steps to calibration are; calculate, select and check. Step one is to calculate the amount of spray solution to be applied per minute. To do this, measure the throughput of potatoes by timing a given weight passing under the application site per minute and multiply by the target application rate. Typically, this is done by timing how long it takes to ll a tonne box. If for example if it takes 7.5 minutes, throughput is 8t/hr or 0.133t/min. Assuming a target application rate of 2.0 litres of spray solution per tonne of seed, as per product labels, multiply throughput of 0.133t/min by 2.0L/t and the required output is 266ml per minute. Step two is to select the appropriate nozzles. With the Team Storemaster, both nozzles are operational for throughputs of 7t/ hr and upwards so each nozzle must deliver 133ml/min. (For throughputs of 6 t/hr and below one nozzle is blanked o .) Refer to the nozzle selection chart and this can be achieved by two white nozzles at 3 bar. e third and nal step is to check that the actual output is in line with the calculated output. Use a measuring jug to check the output per minute and adjust pressure relief valve to set it within +/-5% tolerance laid out in National Sprayer Testing Scheme (NSTS). If there is a signi cant discrepancy refer back to the nozzle selection chart. Application equipment must be NSTS tested every six years and the Red Tractor protocol requires that it should be calibrated between seasons. Compared to the investment in chemical and sta , this is a very small cost which should pay back many times over by avoiding the waste of over or under application and adequately protecting tubers. The operator is crucial e operator’s key responsibility is to maintain an even throughput of crop to maximise coverage and ensure accurate application. Responsibilities at the end of the day are to remove and clean nozzles, empty and clean drip trays underneath the application area and check the suction lter. On direct injection systems ush clean water through the line between injection point and nozzles. For conventional machines, drain any remaining chemical solution from the tank and ush through the whole system. is will stop chemical settling in the pump or pipes and blocking in-line lters or nozzles the following day. At the end of the season, it is important to remove applicators from the grading line and ush through and wash down thoroughly. Use anti-freeze if there is any risk the kit might be exposed to low temperatures. Sta training is crucial to the safe and e ective application of tuber treatments and the person(s) responsible for lling and running the sprayer system should have NPTC units PA1 and PA12 for ‘application of pesticides to material as a continuous process via conveyor, roller table or other equipment’. ■ All photos by Tom England, Albanwise Farming, featuring the new grading and seed treatment line at Low Mowthorpe. “At the end of the season, it is important to remove applicators from the grading line and flush through and wash down thoroughly.” ▲ ▼ A PA12 certificate for applicator operators is compulsory and cleaning and maintenance such as cleaning drop trays should be part of the daily routine. Photo: Tim Scrivener