Apple cultivars investigated as new hosts for two-spotted spider mite, Tetranychus urticae Koch appeared to provide good environment for its development and reproduction. The best conditions for two-spotted spider mite development were on leaves of cultivars Novamac and Freedom with a net reproduction (R_o) 22.6 and 20.3 respectively, while the worst on cultivars Pioner and Primula with R_o 8.9 and 10.2 ,respectively.

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.

Evaluation offruits and leaves ofseventeen apple cultivars in respect of their attraction as food for caterpillars of leafroller species occurring in an experimental apple orchard was carried out over 1995 to 1998 in the Institute of Pomology and Floriculture at Skierniewice. The highest levels ofinjuries were observed on two cultivars: ‘Ligol’ and ‘Elstar’. High number ofinjured fruits was noted on the following cultivars: ‘Gala’, ‘Jonagold’, ‘Cortland’, ‘Idared’, ‘Lodel’ and ‘Szampion’. By far the number of injured fruits was lower on ‘Lobo’ and ‘Jonathan’, and the least on ‘Rubinette’, ‘Starkrimson’ and ‘Gloster’. Significant differences in the number of caterpillars settled down in leaf/flower clusters ofparticular cultivars during the vernal period were also confirmed. In each season the highest number ofcaterpillars of Pandemis heparana and Archips rosana were observed on leaves of‘Alwa’. To cultivars whose leaves were also readily settled down by the two aforementioned species were: ‘Jonathan’, ‘Cortland’, ‘Ligol’, ‘Lobo’, ‘Jonagold’ and ‘Elstar’. Relatively less caterpillars were observed on leaves of‘Arlet’, ‘Gloster’, ‘Szampion’, ‘Starkrimson’, ‘Pilot’, ‘Pinowa’ and ‘Rubinette’.

Number of hairs on abaxial leaf surface of 13 apple cultivars differed significantly. The most hairs per 1 cm² on abaxial surface were on cvs. Lodel (2,578.3) and Jonafree (2,462.2). Leaves of cultivars Antonówka and Novamac had the least number of hairs (1,054.4; 1,285.7; respectively). Correlation between number of hairs on abaxial leaf surface of investigated apple cultivars and Tetranychus urticae (Koch) female fecundity decreased during 10 first days of their lives. Along with increased number of hairs, the fecundity of this species declined.

In this paper the influence of high power airborne ultrasound on drying biological material (Lobo apple) properties is considered. Apple samples were dried convectively at 75 ◦C and air flow of 2 m/s with and without ultrasound assist at 200W. During experiments, sun-drenched and not sun-drenched part of fruits were considered separately to show, how the maturity of the product influences dry material properties. Dried apple crisps in a size of small bars were subjected to compression tests during which acoustic emission (AE) was used. Analysis of AE and strength test results shows that correlations between received acoustic signals and sensory attributes (crispness, brittleness) of dried apples can be found. It was noted that ultrasound improved fruit brittleness in comparison with pure convective processes, where fruit maturity determines a kind of destruction and behaviour of dried apple crisps.

The objective of this study was to investigate the anticoccidial effect of apple cider vinegar added to drinking water with the anticoccidial effect of amprolium to feed broiler chicken. The study has adopted an observational approach to evaluate the anticoccidial effect of apple cider vinegar on broiler chicken. The antioxidative changes were measured adding natural apple cider vinegar to drinking water. Four hundred and fifty broiler chickens were purchased from the local market and distributed into three groups (T+vc: positive control, T-vc: negative control Tv: apple cider vinegar) with 150 chickens in each group. The three groups were further replicated into 3 blocks each containing 50 chickens. The groups were fed balanced diet, amprolium was added to the feed of positive control group, and apple cider vinegar was added to the water of Tv group. Measurements of the different variables were started from week 3, at the end of each week 3 birds were chosen randomly, blood samples were collected via the wing vein, and fecal oocysts were counted from intestinal contents of each individual bird using the McMaster technique. Broiler in the control groups T+ve and T-ve showed clinical signs of coccidiosis (blood in feces) and the number of coccidial oocytes in feces increased with time. In the vinegar group, no clinical signs of coccidiosis were observed. Concentrations of total antioxidants and catalase enzyme activity significantly increased (p≤0.05); while malondialdehyde concentration significantly decreased (p≤0.05).

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.

Observations were carried out in apple orchards and nurseries of the Plovdiv region (Central-South Bulgaria), aimed at determining specific composition, population density and economic importance of particular species of aphids, in the years 2004–2006. By surveys, carried out at 15-day intervals, the appearing species were identified and the degree of damage determined. Six species of aphids were found: Aphis spiraecola Patch., A. pomi Deg., Dysaphis plantaginea Pass., D. devecta Wlk. Rhopalosiphum insertum Wlk. and Eriosoma lanigerum Hsm. A. spiraecola, a poliphagous pest, was probably brought with the plant material from Greece and was identified in Bulgaria for the first time. It is similar to A. pomi and may be distinguished only by the microscopic investigation. Aphis spiraecola replaced almost completely A. pomi in the region studied. Its population was particularly high in nurseries. In the bearing orchards D. plantaginea was the most important aphid. Some tendency to an increase of population and damage caused by D. devecta was also noted. The other species had not any economic importance. E. lanigerum was present only in the orchards where no chemical control was applied.

The leopard moth borer, Zeuzera pyrina L., is a cossid moth whose larvae bore into twigs, branches and trunks of various woody species, weakening and sometimes killing trees or shrubs. Recently it caused serious losses of apple trees in Bulgaria. In a three-year-old non-protected apple orchard in the Plovdiv region more than 30% of trees perished due to damage by this pest. In the nursery and in commercial orchards up to 5% of branches were injured. Main damage was observed in August and September. Both cossids, Zeuzera pyrina and Cossus cossus, damaged 15–20% of the stems in old commercial orchards and more than 60–70% in orchards without regular plant protection. In this study flight dynamics of Z. pyrina was monitored by two types of pheromone traps: Pherocon (Trécé, USA) – traps with sticky changeable bottom and Mastrap (Isagro, Italy) – dry funnel traps. The second type was more effective. Flight of moths lasted from mid-June to the beginning of September. Pheromone traps may be helpful in IPM systems, for signalling optimal time for spraying against this pest. Further studies are needed to determine correlation between the catches in pheromone traps and appearance of injuries.

Studies undertaken in 2002–2004 on ‘Golden Delicious’ apple fruits showed the presence of amino acids on the surface of their skin. Amount of total free amino acids ranged from 2.5 to 3.0 mg/L. In in vitro bioassays it was found that amino acids as a basic source of nitrogen did not activate germination of conidia of Peltaster fructicola (Johnson). However amino acids stimulated elongation of germ tubes and early hyphal growth. It was confirmed that fruit washings also contained sugars that stimulated both conidial germination and germ tube elongation. We proved also that different carbon to nitrogen proportions significantly affected P. fructicola growth. Proportions of C:N were evaluated according to newly introduced amino acid sugar index (ASI)