Integrated Pest Management requires the farmer to recognise the risks to his crops, to take possible non-chemical mitigation or control measures against the pests and only allows the use of chemicals once the pests have exceeded the economic damage threshold.
It is incompatible with Integrated Pest Management, and therefore also legally unacceptable, to apply rigid protection programmes without analysing the appearance of pests. The need to apply chemical protection in the absence of their physical presence in the field is possible on the basis of experience and knowledge of their appearance at a known place and time (e.g. preventive application of seed dressings or soil herbicides before weed emergence) or on the basis of decision-support systems (e.g. targeted application of fungicides when scab or potato blight infection has been detected, although not yet visible). The dosage of the plant protection product must not be higher or more frequent than that specified on its label. Dose reductions are possible, as is the use of mixtures with other registered products that are not specified on the label, but in this case the farmer assumes all responsibility for the outcome of the treatment.
Each plant protection product has specific conditions for its use, both in terms of the development stage of the protected crop, the pest, the intended treatment technique, weather conditions and sometimes the time of day. The aim of these conditions is to safeguard the farmer so that the treatment carried out has the highest efficacy with the least risk to the applicator, the crop, the environment and consumers. This gives rise to a number of practical indications, such as the treatment technique and the permissible time between treatment and rainfall, but also basic indications for the safety of consumers of the crop, people or animals, i.e. the withdrawal period and the withdrawal period for fodder, as well as the time for people to enter the plantation after treatment, and the safety of beneficial fauna (mainly pollinators), i.e. prevention and prevention for pollinators.
The effect of plant protection products is highly dependent on weather conditions and the way the treatment is carried out. Any execution error or weather inconvenience is reflected in the effectiveness of the treatment carried out. The basis for the effectiveness of any product is its presence at the site of action, in conditions that allow it to be taken up by the agrophages. Whether the spray is blown away by the wind, washed away by rain and dew, used at inappropriate temperatures, leading to the product drying out before it comes into contact with the pest, or not accepted because the pest is not biologically active, the effectiveness of the treatment is reduced to as little as zero. Failure to comply with weather constraints, in addition to implementation errors (wrong phase of the pest or poor treatment technique), is the main reason for the low effectiveness of plant protection treatments despite the expense and sometimes environmental contamination.
Spraying crop protection products in windy conditions and before rainfall both causes economic losses in inputs and carries an increased risk of infecting plants with a pathogen against which they have not been adequately protected. Spray drift occurring in windy conditions away from the treatment target area unnecessarily contaminates adjacent areas, especially if there is open water nearby. Similarly, spraying before rainfall is both economically unjustified and environmentally damaging. Most plant protection active substances are toxic to aquatic organisms even in low concentrations. Possible leakage of plant protection products into surface water as well as groundwater should be avoided in every way possible.
Advisory services, offered by, among others, producer companies and commercial units, are common, providing farmers with information, in the form of SMS or smartphone apps, on the optimal timing and dose of application. These services are based on data from local weather stations and official recommendations for the application of plant protection products.
Plant protection products, depending on the purpose of application and field scenario, may need to be used in combination with an adjuvant. Plant protection product manufacturers and independent advisors have knowledge of such needs and proven adjuvants – by following their recommendations, the farmer does not risk loss of yield or quality. The law gives the possibility to use adjuvants not recommended by the plant protection product manufacturer, at the same time indicating the farmer as the person responsible for the results of the treatment. Proposals for mixing various products offered on the market should be approached with great caution, as the rules in force are often exploited by dishonest producers offering untested, often completely unnecessary additives, allegedly enhancing the action of plant protection products, changing the pH of the working liquid, etc., which may reduce the effectiveness of the treatment carried out.