The structure of “green wall” in Gala and Jonagold cultivations differed a lot, this is the reason that the coverage percentages were also very different. The picture bellow shows different coverage rates of WSP (water sensitive papers) positioned on different parts of the tree in cultivation Jonagold. The upper leaves were turned upwards (in the direction of the sky), the ones below are those which were turned downwards. Left picture shows primary driving speed (6km/h) and the right picture shows increased driving speed. Because of the bush tree crowns in Jonagold cultivation the coverage is slightly different than in Gala cultivation, but also here we cannot find major differences.
Different coverage rate with help of WSP in Jonagold cultivation (left 6 km/h, right 9 km/h)
What follows is a statistic analysis of data gathered from WSP (%). According to the opinion of some researchers for average effect of protection agents, 15% of target area should be covered, which means to have 85 droplet prints per cm2 (Deveau 2013). This applies only for foliar application of agents, which have a good secondary distribution.
The deposits were compared to each other with help of statistical software SPSS, which allowed us to prepare an analysis of interaction between deposit in different parts of trees with different driving speeds. Small letters beside the data of deposit are helpful for comparison of deposit of dye in spots of trees in same cultivation and a driving speed. Capital letters show differences in deposit between trees of the same shape (in same spots) in case of different driving speeds.
Results Jonagold cultivation
Deposit quality analysis results with coloured tracer analysis.
Normalized deposit (Jonagold cultivation, double axial ventilator, left tree 6km/h and right 9 km/h). Small letters represent values in different spots of tree with the same working speed, which differ from each other according to the Turkey HSD test (a < 0,05). Capital letters with different fonts represent significantly different values in the same spot of the same tree with 2 different driving speeds.
Results (see picture left and right) show, that the coverage of spots 1, 3, 5 on the external side is better at increased speed (9km/h) than at primary working speed (6km/h). The results in spots 2,6 are statistically the same, the only spot with worse result at increased working speed was in spot 4, which was still reasonably high (61%). Gathered data shows that air resistance of the tree crown in cultivation Jonagold, was higher than in Gala cultivation, which caused bigger airstream bending and resulted in better deposit on outer parts of tree crown and a slightly worse result inside the tree crown.
Deposit results with use of water sensitive papers (WSP).
WSP Coverage rate (%) data. (Jonagold cultivation, double axial ventilators, left tree 6 km/h, right tree 9 km/h, lower set of data -bellow, upper set of data above). Small letters represent values in different spots of tree with the same working speed, which differ from each other according to the Turkey HSD test (a < 0,05). Capital letters with different fonts represent significantly different values in the same spot of the same tree with 2 different driving speeds.
Pictures ( left and right) show spraying results in Jonagold cultivation at 2 different spraying speeds. At higher spraying speed statistically worse deposit can be seen in spot 6 and on lower points (5, 3, 2) which are marked with letter B.
WHY did this happen? The machine produces a slightly different airstream which is whirling, this is the reason that the sprayer is a little more sensitive for increasing of speed. This can especially be seen in cultivation Jonagold, because of lush tree crown. To achieve better results at increasing speed we should also increase the airstream capacity and turns of P.T.O. shaft.
Generally, the sprayer did a very good job, because in majority of spots it achieved normalised deposits, which were higher than 0,5, which grants good impact of protection agents. Results in terms of normalised deposit show better performance than the result of WSP coverage.
The decision of increasing the working speed when spraying depends on interactive effect between sprayer characteristics, airstream produced by the sprayer, tree shape and nozzles used. When increasing spraying speed, we should also adjust the capacity of the fan. Increased spraying speed needs also higher air capacity, except if it is already too high in the beginning.
Are You eager to learn about the results in Gala cultivation, using anti- drift nozzles? Follow us next week and read issue nr. 6.
Zupan Sprayers team wish You nice and successful weekend.