Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

Recommendations for aerial applications of maize granules as carriers of disruptants

An aerial distribution technique for MCA coated grits has been optimised over the 3-year study period. Technical problems have been eliminated and reliable techniques have been developed. The original experimental design has been modified by using regular grit distribution pattern designs covering the whole field. By this technique specific areas of irregular grit distribution in the field can be identified by frequency distribution tables. Subsequent discussions with the pilot helped to understand grit distribution problems at specific sites and to avoid them during future flights.

The airplane has been calibrated appropriately to apply proper rates. An application expert from the Plant Health and Soil Conservation Station in Budapest conducted proper calibration runs. Six aerial applications during 2000/2001 allowed gaining valuable expertise in this application technology. Grit application rate has been increased by 15% after the first application in order to achieve a better coverage at the field margins. Due to his high flight velocity of 170km/h the pilot cannot close the release valves exactly at the border of the field margin.

Therefore, a certain amount of up to 15% has to be added to the application rate/ha. Some degree of deviation in grit distribution patterns can reasonably be accepted. One gram of corn granulate consists of about 300 granules. When applying appr. 18kg of grits/ha, this translates to some 5.4 million granules per ha. With such minute particles one cannot expect perfectly uniform distribution all over the field. Even short wind gusts and air vortices during application can influence distribution patterns significantly. Certain discrepancies between the numbers of grits collected in plastic saucers on the ground in comparison to grits accumulated on maize plants were obvious.

One strategy for the future would be to mix an adhesive material with the granules in orders to make them stick better to the plant surface. Major problems with this approach are
- Reduction of release rate of MCA from the granules and

- Application problems from the airplane or the high clearance tractor because the free flow characteristics of sticky particles are greatly reduced.

Similar problems were encountered in pheromone applications by airplanes for the control of pink bollworm in cotton fields by Brooks et al. 1979 in California. One of their solutions was to design an apparatus mounted on a specially equipped airplane. It carried spools of long plastic tubes filled with the pink bollworm sex pheromone. During flight, these tubes were 1. Simultaneously chopped into short pieces of about 1 inch length and 2. Closed at one end with a drop of adhesive material which let the fibres settle and be glued onto the leaves. This procedure automatically resulted in the open end of the tube standing upright on the leaves and dispensing the pheromone into the surrounding air. This approach, however, needed a lot of mechanical engineering and adjustment. In Southeastern Europe we did not find the necessary infrastructure and therefore decided to try first the much simpler approach of granular application, either by tractor, by helicopter, or by small airplane.

Reported by

Justus-Liebig-University of Giessen
Ludwigstrasse 21
35390 Giessen
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