Chemical plant protection products may only be applied when necessary, when other methods of protection are not applicable, to a specific area of the crop, and the type and amount of product applied corresponds to actual needs.
Plant protection products may be applied with ground equipment as described in the Regulation of the Ministry of Agriculture and Rural Development of 31.05.2014 on the conditions of use of plant protection products (Journal of Laws 2014, item 516), available at: isap.sejm.gov.pl/isap.nsf/DocDetails.xsp?id=WDU20140000516
Plant protection treatments must be carried out using appropriate equipment which meets the requirements of the crop, the weather conditions and the agents used. In the case of field sprayers, the boom must be at the correct height from the crop and in the case of orchard sprayers, it must reach the full height of the tree being treated. If a deeper penetration of the canopy is required, an auxiliary air jet (PSP) is useful. If the wind is likely to interfere with spraying, ejector nozzles are a good option. Plant protection products have different functions, they can have a contact or systemic action, require specific contact with the plant, which implies the need for appropriate nozzles, adapted working pressure, speed of treatment. Seed or planting material treatment equipment must allow for the correct dosage of treatments and optimal coverage of the protected seeds or tubers.
One of the most common mistakes is allowing spray drift. With the current state of agricultural technology, spray drift outside the protected area is inevitable, but spraying must be carried out in a way that minimises this effect, bearing in mind that, by law, wind speeds must not exceed 4 m/s. Some of the spray liquid, in the form of droplets or solids, is carried by air currents away from the area being sprayed during or immediately after treatment. Drift of the spray liquid used to carry out the treatment with plant protection products may result in a reduction in the effectiveness of the treatment and contamination of areas adjacent to the field to be protected. Drift rates are affected by atmospheric and technical factors such as:
- wind speed and direction – wind speed should be continuously monitored using a portable anemometer or by observing the movement of plants and fumes (according to: RDP handbook, Environmental regulations, norms and indicators operating in agricultural production)
| Approximate wind speed (m/s) | Degree on the Beaufort scale | Determination of windiness | Visible signs of wind speed | Recommen¬-dations on spraying options |
| less than 0.2 | 0 | silence | smoke rises straight up | |
| 0.3-1.5 | 1 | breeze | smoke, wind direction can be determined | good conditions for spraying |
| 1.6-3.3 | 2 | slight wind | you can feel the breeze on your face, the leaves are rustling | ideal conditions for spraying |
| 3.4-5.4 | 3 | mild wind | sets the twigs and leaves of trees in perpetual motion | there is an increased risk of drift |
| 5.5-7.9 | 4 | moderate wind | moves small branches, picks up scraps of paper from the ground | spraying is not possible |
- humidity and air temperature – the more windless and sunny the weather, the higher the temperature, the greater the susceptibility of the droplets to drift due to their increased drying,
- droplet size – smaller droplets are more likely to drift,
- working speed – a higher working speed creates air turbulence similar to atmospheric wind, which promotes spray drift,
- height of the spray boom above the spray object – the shorter the distance of the boom from the spray object, the more effective the treatment, but too low a position results in an increase in the amount of spray per unit area,
- air jet speed on AAS (auxiliary air stream) sprayers – the higher the air jet speed, the more effective the drift reduction, but the speed should be reduced when spraying small weeds and at plant emergence to avoid droplets bouncing off the vegetation-free soil surface.
The most common technological solutions that can reduce this are:
- the use of anti-drift and injector nozzles, which produce larger spray droplets,
- keeping the spray boom at a height of less than 50 cm while maintaining an operating speed of less than 8 km/h,
- use of a sprayer with an air sleeve – the air flow emitted through the sleeve creates an air curtain to eliminate the escape of spray droplets; sprayers with adjustable air flow, depending on the direction and strength of the wind, are a good solution,
- the use of tunnel and sensor sprayers (orcharding), directing the liquid directly into the zone with foliage,
- use of sprayers with adjustable droplet size – these allow the droplet size to be varied to suit changing weather conditions,
- planting hedges around fields,
- creation of no-spray zones as a natural buffer around protected fields.
For more detailed information, visit: cdr.gov.pl/images/Brwinow/wydawnictwa/2020/Kodeks_dobrej_praktyki_ochrony_roslin.pdf