Technique of pneumatic pest control

Summary

Objectives: Pest control in organic production of berries, potatoes and vegetables usually employs spreading technique of registered phytopharmaceutical agents. This technique may be supported or even replaced by pneumatic pest control. Up to now there is no evaluation of pneumatic pest control available from agricultural engineering point of view. This paper concerns the following questions: Which techniques of pneumatic pest control are available and how may these techniques be improved in terms of technical and physical parameters?
Hypothesis: Analysis of pneumatic pest control techniques supports improvement of present available implements.
Method: Literature review, process analysis, and evaluation in respect of agricultural engineering parameters (air flow rate, air speed, working hours, energy input, process costs).
Results: Success of pneumatic pest control varies in a wide range, and the technique does not always grant satisfying results. Collection of eggs and larvae is more difficult than collection of adult insects. Usually weekly treatment is necessary. Frequent treatments may cause soil compaction. Pneumatic pest control may distribute fungal infection. Beneficial organisms may suffer from pneumatic techniques. Investment costs of pneumatic implements are high (ca. 5000-12000 €/row). Simultaneously blowing and sucking hoods work better than common suction hoods. Both the interrelationship and the control of physical parameters is almost not subject of research. An analysis of physical parameters and their interrelationships reveals that airflow rate, working width, and travel speed can be comprised within the term air requirement L=te*V where: te is the effective working time and V the airflow rate.
The air requirement correlates with the success of the treatment and is an objective evaluation criterion for the implement and its pneumatic efficiency. The latter may be improved by the following measures: 1) High travel speed prevents pests from escaping the suction hood. 2) Pests sitting upon the plant should start to fly before suction. This may be achieved pneumatically by blowing nozzles and/or mechanically by chains, brushes or similar devices. 3) A suction hood stretched in direction of travel may prolong the duration of pneumatic treatment to ensure successful control. To minimize the tractor power required, the suction airflow velocity under the suction hood should be as low as possible. However, the suction airflow velocity must always be greater than the flying speed of the pest. Low airflow velocity may also contribute to go easy on useful insects. The improvements proposed issue into a design proposal of a stretched hood mounted underneath the tractor. The hood is equipped with blowing and suction orifices and chains to drive the insects off the crop.