Articles
SUMMARY APPLICATION TECHNIQUE
Polesny) mentioned the importance of application techniques as a means to reduce environmental pollution in integrated fruit production (IFP). In lectures and posters only a few aspects of application techniques were discussed.
Emphasis was laid on the use of tunnel sprayers and deposits on leaves.
Both in the Netherlands and in Poland, tunnel sprayers were effective in the control of apple scab.
However, differences in efficacy were noted between the different designs.
In the Netherlands, the sprayer with "Closed Loop System" was more effective than the one with rotary atomizers (Heijne and Porskamp). In Poland, a higher percentage of leaves was infected by apple scab using the tunnel sprayer with cross-flow fans than the tunnel sprayer with directed air-jets (Holownicki, Goszczynski, Doruchowski and Nowacka). Typical for these tunnel sprayers is that they recycle part of the sprayed liquid not deposited on leaves.
The recovered spray liquid is not lost into the environment and is re-used.
A cross-flow sprayer with reflection shielding also recovered part of the spray liquid (Heijne and Porskamp). This sprayer was as effective as the standard cross-flow sprayer in controlling apple scab, while two rows were treated at one time compared to one row with a tunnel sprayer.
Deposits on upper and lower leaf surfaces were distributed more uniformly using a prototype tunnel sprayer with directed air-jets (Holownicki, Doruchowski and Godyn). In this sprayer the air-jets were slightly upwards directed.
Another directed air-jet sprayer (without tunnel) gave the best distribution of deposits on upper and lower leaf surfaces in comparison to a cross-flow sprayer and an axial fan sprayer (Doruchowski, Holownicki and Godyn). Furthermore, this sprayer had highest total deposits on leaves and lowest losses to the environment compared to the other sprayers.
The axial fan sprayer had highest losses to the environment.
Another form of a directed air assistance was demonstrated in strawberries (Labanowska, Doruchowski, Goszczynski and Godyn). This technology was compared to another new sprayer, which not only had one nozzle spraying vertically downward on to the strawberry bed, but also two nozzles spraying horizontally from either sides.
Both sprayers gave good coverage and good efficacy in the difficult to control pests and diseases as demonstrated for spider mites and grey mold.
Doruchowski, Svensson, and Nordmark demonstrated that it is worthwhile to adjust the spray volume to the tree size and volume.
The deposit on leaves increased with decreasing spray volume and tree size.
They estimated that a 50 % reduction of chemicals was possible adjusting the spray volume to 120 1/ha compared to 400 1/ha for super spindle trees.
This "Tree Row Volume"-concept (TRV) can significantly contribute to reduce unwanted emission in IFP.
Several aspects of application techniques need further attention, such as optimum spray volume and improvement of the process of depositing droplets on to leaves with minimum losses of product into the environment.
The efficacy of the deposits might be improved by all sorts of adjuvants.
It should be stimulated to combine measurements of deposits on leaves with an evaluation of the biological efficacy of the pesticides.
I recommend that in IFP, the droplet size should be restricted to droplets larger than 80 μm, to reduce drift.