KiwiTech Bulletin No. N79 Low Drift Spraying: Calibration & Set-up June 2010

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1 KiwiTech Bulletin No. N79 Low Drift Spraying: Calibration & Set-up June 2010 Sustainable production of kiwifruit requires orchardists to use environmentally friendly practices to meets the needs of our markets, the communities in which we live and legal requirements both here and in the countries we export to. From a spraying viewpoint early season applications, while being the most important in regards to vine productivity and pest control, are also the ones that have the greatest risk of off target spray losses and potential environmental impact. Any agrichemical drift beyond sprayed blocks should be avoided. Drift into sensitive areas (houses, schools, roadsides, waterways, other crops etc) is simply unacceptable. Risks of off target spray losses at potentially damaging levels are greatest during dormant applications when there is no canopy present to trap the spray. Figure 1. Projection of some spray above and beyond the canopy is necessary to ensure spray coverage - but how far beyond? Drift typically occurs through a combination of; spraying under inappropriate conditions poor sprayer setup and operation spray being projected into the air above and beyond the canopy where small droplets can drift beyond the block boundaries. Using conventional airblast spraying practices, downwind spray losses at 10 and 30m from the edge of fully foliated canopies can be as high as 2% and 0.02% of the applied chemical rate respectively. Unfortunately, without a canopy and/or shelter to trap droplets, losses can be as high as 20% of the applied rate at 10m and still be around 2% out to 30m (Figure 3). Figure 2. Low drift nozzles and good sprayer setup are keys to minimising overspray and avoiding losses onto sensitive areas. Page 1 of 9 N79: Rev 0: 06/2010

2 Eliminating off target loss of spray requires; 1) Low drift nozzles & associated adjuncts 2) Use of appropriate travel speeds, air outputs and nozzle arrangements 3) Operator care when turning in and out of rows and when spraying edge rows 4) Spraying under appropriate wind conditions. Nozzle output angles Nozzle output angles determine how far the spray can be projected and still maintain good coverage. Downwind deposit (% of applied rate) Downwind spray losses on dormant versus fully foliated canopy Dormant losses (% of applied rate) Losses at full canopy (% of applied rate) Distance from edge of sprayed block (m) Figure 3. Potential downwind off target spray losses when spraying dormant versus fully foliated canopies with no shelter belt present (NZ apple data). The narrow, medium and wide outputs referred to in the text relate to the following approximate angles; narrow 18 o to 42 o medium 43 o to 65 o wide 66 o to 80 o Nozzles for treating pergolas For spraying pergola the lowest nozzle that can effectively be used will be just above the midheight of the fan. Numbers of usable nozzles depends on the make of sprayer, but typically will be; four on a 6-a-side sprayer five on a 7-a-side sprayer six on an 8-a-side sprayer six on a 9-a-side sprayer eight on a 10-a-side sprayer Figure 4. Narrow angle D Series solid cone nozzle which can project out to leaders (top) versus a wide angle Air Inclusion flat fan nozzle which is only suitable for coverage of canes close to the sprayer. Switching to large droplet Air Inclusion nozzles can decrease downwind losses over 10m from the sprayer by more than 75%. Conventional disk and core nozzles produce large numbers small droplets that can drift down wind and potentially move off target. Page 2 of 9 N79: Rev 0: 06/2010

3 Calibration and sprayer setup Travel speeds and spraying patterns Different sprayer fans and fan pitches will deliver different patterns of air into the canopy. How fast a sprayer can travel is ultimately determined by whether it can achieve even coverage on target canes under the wind conditions at the time of spraying. Experience has shown that travel speeds of between 4.0 and 5.5 km/hr should achieve effective responses to hydrogen cyanamide applications. Spray coverage in the leader region of vines on wider (>4.5m) row spacings can be difficult and faster speeds may give uneven coverage the leader zone, so consider using slower speeds on wider row spacings. Travelling at speeds faster than 5.5 km/hr on narrow row spacings may be possible, but should only be done if coverage is obviously not compromised. nozzles with narrow output angles to ensure chemicals reach the target. Pergola canopies General recommendations for the proportion of output and spray output angles from different nozzles required for pergola canopies on different row spacings are given in Tables 1 and 2. In each case the lowest nozzle on each side should target the vine leader, with the second nozzle from the bottom on each side targeting the region just above the leader. All single axial fans rotate counter clockwise and "dump" to the left hand side of the sprayer (looking from the rear). This dumping effect is seen more with some types of fans than others (eg Exel and Pearce), and nozzles may have trouble pushing upwards through the dumped air. Application to every row, with alternate rows being sprayed from opposite directions remains the preferred pattern for spraying. Application volumes and chemical rates Chemical application rates must never exceed those stated on the chemical label. Standard industry practice for hydrogen cyanamide applications has been based on 4% to 6% product in 600 litres of water per hectare (24 to 36 litres of product per hectare). In general, the use of higher application volumes will help overcome potential gaps in spray coverage and wetting and the use of 5% product in 700 litres of water per hectare is an application option that has been used successfully and should be considered if coverage at lower volumes appears patchy. Nozzle output arrangements for different sprayers and row spacings Knowing where the spray is to be placed (the target) is essential for effective agrichemical application. For hydrogen cyanamide, even spray coverage of all dormant buds is required to achieve maximum efficacy. However, excessive wetting with drip points can cause bud burning. Nozzle selection and arrangement to suit different sprayers and row spacings is the key to achieving even coverage without excessive wetting. Operators should have a clear understanding of which part of the canopy each nozzle targets. Regularly check spray coverage on canes near the leader and on the top surfaces of canes where coverage is most difficult to achieve.(refer to KiwiTech Bulletin N55: Assessing Spray Coverage). As the row spacing widens it is necessary to use Figure l/ha with standard nozzles (top) versus AI nozzles (below). Page 3 of 9 N79: Rev 0: 06/2010

4 Table 1 Nozzle output angles and proportion of flow recommended from a seven nozzle sprayer to pergola canopies on different row spacings nozzle # 5m 4.5m 4m 3.5m 3m (1=top) angle % angle % angle % angle % angle % 1 wide 12 wide 12 wide 16 wide 16 wide 23 2 wide 16 wide 16 wide 21 wide 21 wide 32 3 medium 21 medium 21 medium 28 medium 28 medium 45 4 narrow 27 narrow 27 narrow 35 narrow 35 off 5 narrow 24 narrow 24 off off off 6 off off off off off 7 off off off off off Table 2 Nozzle output angles and proportion of flow recommended from an eight nozzle sprayer to pergola canopies on different row spacings nozzle # 5m 4.5m 4m 3.5m 3m (1=top) angle % angle % angle % angle % angle % 1 wide 9 wide 12 wide 12 wide 16 wide 16 2 wide 12 wide 16 wide 16 wide 21 wide 21 3 medium 15 medium 21 medium 21 medium 28 medium 28 4 medium 20 narrow 27 narrow 27 narrow 35 narrow 35 5 narrow 24 narrow 24 narrow 24 off off 6 narrow 20 off off off off 7 off off off off off 8 off off off off off Table 3 Nozzle output angles and proportion of flow recommended for T-Bar canopies that have been tied down ( m row spacings) nozzle # Seven nozzle sprayer Eight nozzle sprayer (1=top) angle % angle % 1 off off 0 2 off off 0 3 narrow 25 narrow 20 4 narrow 32 narrow 25 5 medium 25 narrow 23 6 wide 18 medium 20 7 off wide 12 8 off Table 4 Nozzle output angles and proportion of flow recommended for T-Bar canopies that have not been tied down Eight nozzle sprayer nozzle # 5 m row 4.5 m row (1=top) angle % angle % 1 off 0 wide 9 2 wide 12 wide 12 3 medium 16 medium 15 4 medium 21 medium 20 5 narrow 27 narrow 24 6 narrow 24 narrow 20 7 off off 8 off off Page 4 of 9 N79: Rev 0: 06/2010

5 Table 5 - The effect of pressure on droplet size from AgroTop TD Air Inclusion nozzles with different output angles Pressure (KPa) Volume Median Diameter (microns) TD o TD o TD o T-Bar canopies To achieve even coverage on T-Bar canopies it is necessary to direct some of the spray plume right through the canopy to hit the back sides of canes on the far side from the sprayer. Typically the top nozzle used (Tables 3 and 4) targets the adjacent shoulder of the canopy, the second nozzle down targets the leader, the third nozzle down targets the opposite shoulder and the lowest nozzle(s) targets the adjacent and tied down canes on the far side. It is generally necessary to turn off the top nozzles when spraying T-Bar canopies as spray from these tends to be directed into the air above the canopy where it can be lost as drift. If T-Bar canopies are not pruned or tied down at the time of spraying a greater percentage of the spray plume will need to be directed out of the top nozzles as shown in Table 4 for an eight nozzle sprayer. Spray droplet sizes and Air Inclusion (AI) nozzles Standard disk and core nozzles used for budbreak sprays produce spray droplets in what are termed Fine to Medium size classes. Droplet diameters (VMD) from fine and medium spray plumes are around 150 and 250 microns respectively and there is potential for droplets in these sizes to move off target. Unfortunately there are fewer larger droplets produced from any given volume of spray mix and conventional large droplets show poor retention, coverage and agrichemical efficacy on targets like kiwifruit canes. bubbles inside them which reduce the liquid volume contained in the droplet and give a relative improvement in the adhesion and spreading characteristics. Despite this, the observed coverage of AI droplets on targets like kiwifruit canes will always appear more patchy and uneven than that from the same volume of spray applied using smaller droplets. In order to compensate for this in early season kiwifruit spray applications, it is important that AI nozzles are used with an appropriate spray adjuvant that will enhance droplet adhesion and spreading, without causing the collapse of the air bubbles that are so important to the performance of these nozzles. Most nozzle manufacturers now offer a range of AI nozzles, but not all will be suitable for use in kiwifruit. The trial work conducted in kiwifruit indicates that AI nozzles will only be useful as a drift mitigation tool for early season applications to canes (in experiments to date AI nozzles used alone have not performed as well as current industry standard nozzles in canopies at full leaf). A range of AI nozzles have been considered and tested over three seasons and example AI nozzlings have been prepared for different use situations (Table 6). These examples are by no means the only options for setting up sprayers for low drift application of hydrogen cyanamide. However, they currently represent the best practice recommendations. Nozzles from two different manufacturers have been recommended, the Albuz TVI nozzles which are wide angle hollow cones (Figure 6) that have a low profile and are unlikely to hook up on canes when spraying and the Agrotop TD (Turbo Drop) nozzles (Figure 7) which make use of an AI body placed before a conventional nozzle. This nozzle is quite long and potentially prone to catch on canes, however Agrotop produce a range of narrow angle (40 o and 60 o ) flat fan nozzles that are ideal to project the spray towards leaders on wider row spacings. Both nozzles are made of plastic with ceramic inserts at potential wear points so can be expected to provide several seasons of effective use. The recent introduction of large droplet Air Inclusion (AI, sometimes called Air Induction) nozzles has allowed large drift reducing spray droplets to be used on many (mainly arable) crops without compromising agrichemical efficacy. AI nozzles produce large droplets which are typically in Coarse to Very Coarse size classes with virtually all droplets over 250 microns in diameter (Table 5). These have a much lower risk of off target drift than Fine or Medium droplets. Unlike large droplets from conventional nozzles, AI nozzle droplets have air Figure 6. Albuz TVI cone nozzle with inner section shown. Page 5 of 9 N79: Rev 0: 06/2010

6 Adjuvants to enhance spray performance and/or reduce drift A range of spray adjuvants were tested in trials with HiCane for both spray drift reduction from conventional nozzling and for drift reduction and improved coverage from AI nozzles. The drift reduction performance from the AI nozzles was so great and so consistent that this technology has been selected as the best option for drift risk mitigation. However, large droplets bounce more and give less uniformity on canes than small droplets. An adjuvant partner is thus required to ensure that hydrogen cyanamide efficacy was maintained. Figure 7. Agrotop Turbodrop fan nozzles. The AI nozzles (plus adjuvant) have performed consistently in the tests conducted. They reduced off target losses at 10m or greater from the sprayer in excess of 70% compared to conventional nozzles. These levels of drift reduction have been achieved at both low and high wind speeds. However, it is important to note that AI nozzles are not a total solution to spray drift issues and operator decisions on wind conditions and risks around sensitive areas remain critical to avoiding spray drift. The Nufarm adjuvant Driftstop TM was selected after extensive testing for use with AI nozzles and HiCane applications and presently is the only adjuvant partner recommended for these applications. The adjuvant has drift mitigation properties as well as the ability to improve droplet adhesion and coverage. All directions and warnings on the hydrogen cyanamide and Driftstop labels must be followed. Table 6 Example Air Inclusion nozzle recommendations 1 for application of hydrogen cyanamide sprays to different canopies and row spacings using a seven nozzle sprayer. nozzle # Pergola T-Bar (1=top) 5m 4m 3m 5m 2 1 TVI TVI TVI off 2 TVI TVI TVI off 3 TVI TVI TVI TD TD TD off TD TD off off TVI off off off TVI off off off off 1 TVI = Albuz hollow cones air inclusion nozzles, wide angle (80 o ) output TD = Agrotop flat fan air inclusion nozzles, 60 o or 40 o output angles 2 Tied down Page 6 of 9 N79: Rev 0: 06/2010

7 AI nozzle output tables, required output volume tables ALBUZ TVI Air Inclusion hollow cone nozzles expected outputs Pressure (Kpa) Output l/min Purple TVI Pink TVI Green TVI Yellow TVI Lilac TVI Blue TVI AGROTOP TD Flat Fan Air Inclusion nozzles expected outputs Pressure (Kpa) Output l/min Lilac TD 60/40/ Blue TD 60/40/ Red TD 60/40/ Brown TD 60/40/ Grey TD 60/40/ Sprayer output required to deliver 600 l/ha for different row spacings and travel speeds Speed (km/hr) Row spacing (m) Sprayer output required (litres/minute) Sprayer output required to deliver 700 l/ha for different row spacings and travel speeds Speed (km/hr) Row spacing (m) Sprayer output required (litres/minute) For more information on the recommended AI nozzles see the manufacturer web sites or contact the NZ suppliers below: ALBUZ NZ supplier Silvan AGROTOP NZ Supplier Croplands Page 7 of 9 N79: Rev 0: 06/2010

8 As a rule of thumb, an effective air output will consistently project the spray from the leader nozzle to just beyond the leader on the upwind side of the canopy. Figure 8. Spraying with too much air, this plume was projected over 7m above the canopy! Managing air outputs It is easy for airblast sprayers to deliver too much air when applying dormant sprays. Ideally the air output should be set to provide the minimum required to consistently see the spray plume reach just beyond the vine leader on the upwind side of the sprayer. The fan speed required to achieve this will vary with fan size and pitch and the total amount of air required will vary with row spacing, spraying travel speed and wind conditions. The large number of variables involved makes it impossible to set any specific guidelines on air output management; however the following points should always apply; Some air output will be required to assist and ensure coverage on all but the closest row spacings under very calm conditions Sprayer fans do not need to be operated at 540 rpm and most pumps will operate effectively at pto speeds down to about 440 rpm. However, if reducing PTO speed check that the fan clutch properly engages. It may be necessary to bring the sprayer up to the normal 540 rpm PTO speed and then drop the engine rpm back from there An easy way to reduce the air output volumes and speeds from large fans is to cover the inlet screen of the fan with two to four layers of shade cloth. It is important to evenly cover the whole inlet area and to secure the layers of cloth in place with bungy cords or similar to prevent them being sucked into the fan. The approximate reductions in air outputs from one, two or six layers of cloth are 20%, 60% and 70% respectively Sprayer air output volumes of no more than ~20,000 m 3 /hr will usually be required for dormant canopies. While this is less than a third of the output volume potential from a large 920mm diameter axial fan sprayer, this volume of air is still capable of carrying small spray droplets several metres beyond the sprayer where they can be lost as drift. This implies that there will always be a risk of drift losses to sensitive areas where sprayers produce small droplets. The ways to avoid this are; increase droplet sizes and/or treat blocks near sensitive areas when there is a consistent breeze blowing off the sensitive area and into the treated block allow for an in-orchard buffer zone. Note: This KiwiTech Bulletin replaces the Kiwifruit Spraying: Application of Budbreaking Sprays document and should be read in conjunction with Bulletin N80: Low Drift Spraying; Application. Additional Reading ZESPRI Crop Protection Programme KiwiTech Bulletin N39: Best Practice Spraying KiwiTech Bulletin N55: Assessing Spray Coverage Manktelow D., Gaskin R., May B., You won t get my drift. NZ Kiwifruit Journal July 2006 Manktelow D., Gaskin R., May B., Snelgar B. Will it still work? Or are low drift treatments going to compromise hydrogen cyanamide efficacy? NZ Kiwifruit Journal Jan 2007 Acknowledgements The research on low drift spraying to minimise potential off target agrichemical losses is supported by KGI and the MAF Sustainable Farming Fund. This project builds on low drift adjuvant work commenced by Nufarm ZESPRI Group Limited. All rights reserved. ZESPRI Group Limited and/or its subsidiaries ( ZGL ), and The New Zealand Institute for Plant & Food Research Limited ( Plant & Food Research ) have endeavoured to exercise reasonable skill in obtaining and presenting the information in this document and its attachments. However, neither ZGL nor Plant & Food Research makes any warranty, representation or guarantee as to the accuracy or completeness of the information in this document or its attachments in any way and neither ZGL nor Plant & Food Research shall be liable to any person for any loss arising from that person s reliance on the information. Page 8 of 9 N79: Rev 0: 06/2010

9 Thanks to Silvan New Zealand and Croplands for assistance with sprayers and supply of AI nozzles. Authors David Manktelow, Applied Research & Technologies Robyn Gaskin, PPS NZ Bill May, Spraytec Shane Max, ZESPRI Tech Transfer ZESPRI Contact Details Grower Contact Centre: Website: ZESPRI Group Limited. All rights reserved. ZESPRI Group Limited and/or its subsidiaries ( ZGL ), and The New Zealand Institute for Plant & Food Research Limited ( Plant & Food Research ) have endeavoured to exercise reasonable skill in obtaining and presenting the information in this document and its attachments. However, neither ZGL nor Plant & Food Research makes any warranty, representation or guarantee as to the accuracy or completeness of the information in this document or its attachments in any way and neither ZGL nor Plant & Food Research shall be liable to any person for any loss arising from that person s reliance on the information. Page 9 of 9 N79: Rev 0: 06/2010