Fruit and vegetables constitute an essential part of human diet and that is why they should be “safe”.

Chemical contaminants of plant origin in food, including the pesticide residues, are defined as critical differentiators of quality and food safety. Pesticide residues are found in fruits, vegetables, cereals and herbs chemically

protected at low concentrations, but they are one of the elements that affect the quality of healthcare.

The aim of this study was to assess the pesticide residues in apples from the north-eastern Poland (Lubelskie,

Podlaskie and Warmińsko-Mazurskie provinces) and get an answer whether any contamination in fruit from the

region is similar to that in other countries and whether it can lead to exposure of consumer’s health. Also assessed compliance of used pesticides with applicable law and found residues were compared with the Maximum

Residue Levels (MRLs). The study showed that 59% of the samples of apples from the north-eastern Poland

contain pesticide residues below the MRL, and 7% above the limits. The estimated dietary intake has shown

the chronic dietary exposure of the most vulnerable groups - children and adults to the pesticide residues in

Polish apples was relatively low and does not constitute a health risk to. The results show that apples from

north-eastern Poland are safe.

Atmospheric precipitation is the major input to the soil water balance. Its amount, intensity, and temporal distribution have an indubitable influence on soil moisture. The aim of the study (conducted in the years 2010–2013) was to evaluate soil water balance in an apple orchard as determined by daily rainfall. The amount and intensity of rainfall and daily evapotranspiration were measured using an automatic weather station. Changes in soil water content was carried out using capacitance probes placed at a depth of 20, 40 and 60 cm. The most common were single events of rainfall of up to 0.2 mm, while 1.3–3.6 mm rains delivered the greatest amount of water. A significant correlation was found between the amount of daily rainfall and changes in water content of individual soil layers. The 15–45 cm and 15–65 cm layers accumulated the greatest amount of high rainfall. The study showed a significant influence of the initial soil moisture on changes in the water content of the analysed layers of the soil profile. The lower its initial moisture content was, the more rainwater it was able to accumulate.

The aim of the research was to evaluate effects of different rootstocks and management practices to counteracting replant disease in an apple orchard. The experiment was conducted in the Experimental Orchard of the National Institute of Horticultural Research in Dąbrowice, Poland, in 2014–2020. Apple trees of the cultivar ‘Ligolina’ were planted in autumn of 2013 at spacing of 3.8 × 1.4 m in the rows of an apple orchard that had been grubbed up in spring. The following experimental setups were used: (i) two types of rootstocks of different growth vigour (M.9, P14); (ii) replacement of soil in rows of trees with virgin soil; (iii) fertigation with ammonium phosphate; (iv) control (cultivation in the exhausted soil). Replantation significantly limited the growth of apple trees by reducing the cross- sectional area of the tree trunk, and the number and length of annual shoots. Fruit yields of apple trees grown on the replantation site were significantly lower than those of the trees grown in virgin soil. The use of ammonium phosphate fertigation had a positive effect on the growth and yield on the replantation site, especially when it was combined with the use of a stronger-growing rootstock (P14). The most effective environmentally friendly method of eliminating the apple replant disease is the replacement of the exhausted soil with virgin soil, i.e. soil that has not been used for growing fruit trees before.

A machine learning model was developed to support irrigation decisions. The field research was conducted on ‘Gala’ apple trees. For each week during the growing seasons (2009–2013), the following parameters were determined: precipitation, evapotranspiration (Penman–Monteith formula), crop (apple) evapotranspiration, climatic water balance, crop (apple) water balance (AWB), cumulative climatic water balance (determined weekly, ΣCWB), cumulative apple water balance (ΣAWB), week number from full bloom, and nominal classification variable: irrigation, no irrigation. Statistical analyses were performed with the use of the WEKA 3.9 application software. The attribute evaluator was performed using Correlation Attribute Eval with the Ranker Search Method. Due to its highest accuracy, the final analyses were performed using the WEKA classifier package with the J48graft algorithm. For each of the analysed growing seasons, different correlations were found between the water balance determined for apple trees and the actual water balance of the soil layer (10–30 cm). The model made correct decisions in 76.7% of the instances when watering was needed and in 87.7% of the instances when watering was not needed. The root of the classification tree was the AWB determined for individual weeks of the growing season. The high places in the tree hierarchy were occupied by the nodes defining the elapsed time of the growing season, the values of ΣCWB and ΣAWB.

The aim of this research was to prepare the basis for the certification of the apple orchard protection program by determining disappearance models for active ingredients (AIs) of plant protection products (PPPs) in fruits. Field trials were carried out in a conventional apple orchard protected with PPPs in accordance with the currently adopted program. Residues of their AIs were determined using Agilent GC-MS/MS 7000D and LC-MS/MS 6470 QQQ, and their decreases were expressed by the exponential formula: R _t = R ₀ × ^{e–k × t}. Of all the AIs found in mature fruits, captan disappeared at the fastest rate [t _(1/2) in the range of 9 to 13 days], followed by fluopyram [t _(1/2) = 13 days], tebuconazole [t _(1/2) = 14 days] and carbendazim [t _(1/2) in the range of 24 to 32 days]. With the exception of dithiocarbamates and some fungicides (e.g., Captan 80 WDG) based on captan and methyl thiophanate, other insecticides and fungicides currently recommended can be used up to 3 months before harvest practically with virtually no restrictions. From July 15 to August 15, the chemicals effective at application rates not exceeding 0.3 kg of AI per ha should be used. To protect apples against storage diseases, PPPs that are effective at a dose ≤ 0.1 kg AI per ha (e.g., certain triazoles or strobilurins) and applied not later than 1 month before harvest, should be used.