A New Technique for Safe Pesticide Spraying in Greenhouses

Protection from parasites is an important factor in agricultural operations, and calls for continual monitoring and prompt action when needed. In many cases, the equipment, pesticides and manpower required for this purpose account for the majority of production expenses. Though the use of chemicals has had a major influence on the development of agriculture in the twentieth century, bringing significant benefits, it has also had many side effects on human health, animals and the environment. The ease with which these substances can be used, their initial low cost and the lack of knowledge on the part of growers has led to an overuse of pesticides, with dangerous consequences. Only in the last few years have agricultural techniques brought about improvements in the pesticides used (Hewitt, 2000). There can be no doubt that advances in this field have provided a more effective range of choices, for growers and the environment in particular. Parasites must thus be combated by producing a climate that is unfavourable for them, as well as by using a forceful, accurate and incisive spray technique. To reduce pesticides by using more effective treatments, recent studies have investigated different spray techniques capable of reducing the pesticide dose with very low waste and outflow (Austerweil & Grinstein, 1997). Efficacy of crop spraying depends on two main factors: coverage density and uniformity, and droplet size. For the first factor, it should be emphasised that droplets should reach leaves without any overlapping. The second factor is important because many studies have shown that coarse droplets reduce spraying treatment efficacy. In fact, smaller droplets penetrate the canopy better and, transported by air, can reach each part of the crop without dispersion. This is especially true in the greenhouse, where wind is not a problem. These considerations have spurred interest in the idea of spraying pesticides in a defined volume, i.e., a confined area (Moltò et al, 2001) (Ebert et al, 2003). The first step in designing an innovative pesticide sprayer is to study various spraying techniques.