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Apple scab, caused by Venturia inaequalis, is one of the most damaging pathogens affecting apple species. Cross combinations were made between the Salva cv. (female parent), a valuable local cultivar known for its fruit quality and used as a donor of the Vf resistance gene, and Jonathan (male parent), a variety widely cultivated but susceptible to scab. The Vf gene was first identified in Malus floribunda Clone 821, which was subsequently transferred to commercial varieties through various breeding programs. To confirm the presence of the Vf gene, the progeny from this cross was tested using Marker-Assisted Selection (MAS) with one dominant primer pair (AM19) and two codominant primers (AL07 and VFC) to distinguish between homozygous and heterozygous genotypes. From the crossing, 67 hybrids were obtained, of which 35.8% (24 hybrids) were classified as resistant (heterozygous - Vfvf), while 64.2% (43 hybrids) were classified as susceptible (recessive homozygotes - vfvf). This population of hybrids resistance to Venturia inaequalis represents a good starting point in obtaining cultivars with resistance to scab.

Erwinia amylovora is the most damaging bacterial disease of quince, causing a lot of damage to this crop. In cases of severe infections, this disease could even cause the death of the tree. The climatic conditions in Bistrita region were favourable for fire blight outbreak in 2022, and gave us the opportunity to study the differences manifested by five quince cultivars ('Aromate', 'Aurii' 'Bereczki', 'Adonia' and 'Cedonia') when naturally infected with Erwinia amylovora Burrill. The second wave of infections, in September, was significantly less damaging than the first one which occurred in June. Overall, after assessing the frequency of the blighted shoots of the mentioned quince cultivars, in June and in September of the year 2022, we concluded that there were significant differences between responses to natural infection Erwinia amylovora of these cultivars. The data showed that the cultivars 'Aromate' and 'Aurii' have a better behaviour than the Hungarian cultivar 'Bereczki', while the Romanian cultivars 'Adonia' and 'Cedonia' appeared to be very susceptible under the climatic conditions of the year 2022 in Bistrita area.

Apple is one of the most consumed fruits in the world and as well one of the most important crops in temperate areas. Apple scab, caused by Venturia inaequalis is damaging diseases that affects apple species and causes up to 70% yield losses depending of cultivar’s resistance. In order to control this disease, costly chemical pesticides are necessary, which increase the pollution of environment by their toxicity. This study is focused on checking the behaviour of certain apple varieties from the pomological collection at UASVM Cluj-Napoca against apple scab infection. Nine apple cultivars ('Fuji Kiku', 'Red Cap', 'Lena', 'Katja', 'Gala Mitchgla', 'Fiesta', 'Yellow', 'Pinova' and 'Reinette du Canada'), were analysed in terms of behaviour to scab attack on leaves and fruits. Visual observations were completed by molecular analyses for the potential presence of the Vf gene in some cases. Combining results from visual observation and molecular assays, the 'Lena' and 'Pinova' cultivars were noted as resistant to scab in our field trial conditions. This indicates a good opportunity to bring them into apple breeding programs for resistance to apple scab.

Black chokeberry (Aronia melanocarpa Michx.) is one of the most cultivated species in recent years, gaining consumer appreciation due to its fruit’s bioactive compounds. This aim of this paper was to study the behavior of two chokeberry cultivars ‘Viking’ and ‘Galicjanka’ under climatic factors in Bistrita area, within an experimental plot established at Fruit Research and Development Station Bistrita. Resistant to low temperatures but sensitive to drought, the two chokeberry cultivars ‘Viking’ and ‘Galicjanka’, have recorded a positive development evolution in pedoclimatic conditions in Bistrita area. For the success of this crop, it is necessary to ensure all the parameters to obtain a high-quality production, so that the deficiencies caused by insufficient water supply can be prevented by implementing technological measures that reduce the negative impact of the ever- changing environment.

Plum pox virus (PPV) is considered the most detrimental viral pathogen of stone fruits, causing important economic losses. Exhaustive studies revealed that D, M and Rec are the prevalent strains of PPV in Europe. While different experimental reports revealed that PPV-M is more aggressive than PPV-D, limited information is available about the competitiveness of PPV-Rec under field conditions. Also, symptoms developed by PPV-Rec infection are scarcely documented. To increase this knowledge, we selected and monitored an experimental plum orchard already contaminated by both PPV-D and PPV-Rec. The disease spread was monitored by visual observation and ELISA testing each year along five consecutive vegetative periods. The dynamic of single and mixed infections was assessed by molecular strain typing (IC-RT-PCR) of all newly and single-infected trees. While the disease prevalence increased almost linearly, the number of single PPV infected trees (either by PPV-Rec or by PPV-D) remained relatively stable during the five-year period of monitoring, which is explainable by the continual increase of the number of trees infected with both strains together. No significant difference in the progression rate between D and Rec strains was found when considering their presence in both single and mixed infections. Although the types of PPV symptoms developed on leaves and fruits varied among cultivars, no clear-cut D or Rec strain-specific symptoms were developed within the same cultivar. Overall results revealed that PPV-D and PPV-Rec strains had similar behaviour in terms of competitiveness and symptoms developed under our experimental field conditions.

Scab resistance through the Rvi6 gene was largely used in Romanian breeding programs including those from Fruit Research & Development Station (FRDS) Bistrita. The aim of the study was to verify the efficacy of the resistance due to the Vf gene under the current conditions in the Bistrita area. Three scab resistant apple cultivars bred at FRDS Bistrita were monitored in the field, in comparison with the Rvi6 ‘Florina’ and ‘Prima’ cvs., and the sensitive ‘Idared’ and ‘Golden Delicious’ cvs. Molecular markers (AM-19, U1₄₀₀ and AL07) were used in PCR to check the presence of the Rvi6 gene in the genome of the three Romanian varieties. During the years 2019-2021, scab lesions appeared on all the resistant cultivars studied. PCR results showed the presence of Rvi6 gene on ‘Bistritean’, ‘Salva’, ‘Aura’, ‘Prima’ and ‘Florina’ genoms. The results suggest a possible breakdown of the resistance given by the Rvi6 gene in the current ecological conditions in this area. Scab symptoms occurring on cultivars that have the Rvi6 gene could lead to the hypothesis that different scab races are now present in our area or that some genetic variations occurred on the existing races so that they overcome Rvi6 gene.

To reduce economic losses caused by viruses and phytoplasmas, one of the main preventive measures is to use 'certified' plant material. A nuclear-stock plum collection under insect-proof house is conserved at FRDS Bistrița and consists in twenty-one varieties and one rootstock used for stone fruits propagation. A widening of Romanian plum varieties at Pre-basic category is required to create the opportunity to establish a larger national valuable nuclear-stock collection and to secure the prerequisite for a good transfer of Romanian plum breeding results to the practical application. Plants belonging to other six Romanian plum varieties (Diana, Silvia, Tita, Pescăruș, Gras românesc and Tuleu dulce) were monitored in the field along two consecutive years for potential viral symptoms and tested by serological and molecular tools according EPPO standards. Selected trees of each variety were grafted onto virus-free Saint Julien rootstocks, into insect-proof house, and retested. Three grafted plants from each of the six varieties were chosen to become Candidate Pre-basic material and they were biological indexed onto virus free plants of GF 305. Thus, candidate Pre-basic material, the precursor for Pre-basic category, was established to other six valuable Romanian plum varieties.

Apple scab, caused by Venturia inaequalis is one of the most damaging pathogens that affects apple species. Cross combinations were made between Auriu de Bistrița cv. (female genitor) - a valuable local variety in terms of fruit quality but only tolerant to scab, and Florina cv. (male genitor) used as a donor of Vf resistance gene. It was first detected in Malus floribunda Clone 821, which was later transferred to commercial varieties by different breeding programs. To confirm the presence of Vf gene, progenies resulting from the mentioned combination were tested with MAS (Marker Assited Selection), using two dominant primers pairs (AM19, U1400), and another one codominant (AL07) used to distinguish homozygous and heterozygous genotypes. After the crossing combination, a number of twenty-six hybrids were obtained, of which 50% (13 hybrids) were clasified as resistant (heterozygous), respectively 50% (13 hybrids) as susceptible (recessive homozygotes), so the Mendelian ratio was confirmed.

Ecological farming is increasing worldwide, as more and more consumers prefer chemical-free fruits. As a result, ecological farming is becoming increasingly appealing to European farmers, including those in Romania. However, implementing an effective ecological phytosanitary program remains a challenge for farmers due to limited options and a lack of information about their effectiveness. Romania is a major producer of plums and ranks second in the world after China. Aphids are common pests of plum, and some species are vectors of the damaging Plum pox virus, and therefore require special attention regarding their control. Eight ecological products were tested both in the field and laboratory for a duration of three vegetative periods to determine their efficiency in aphid control. The effects of ecological products were compared with five chemical insecticides known to be effective against aphids. Observations were made 24 and 48 h after spraying. Two of the eight ecological products tested were proven to be efficient in aphid control, Ovipron Top and Prev-Am, with a mortality rate over 90%. The results indicate that these two ecological products are comparable in effectiveness to chemical insecticides and could be suitable candidates for both ecological and conventional treatment programs.

Sixteen plum and eleven sweet cherry newly established commercial orchards in Transylvania, Romania, were the subject of the survey during the vegetative periods of 2020-2021 in order to assess the occurrence of different virus infections. Two blocks of 200 trees from each orchard were monitored by visual observation for virus-like symptoms, especially for Plum pox virus (PPV) in plum orchards. Twenty trees of each plum orchard were then sampled and tested for serological detection of PPV, Prune dwarf virus (PDV), Prunus necrotic ringspot virus (PNRSV), Apple chlorotic leaf spot virus (ACLSV), Apple mosaic virus (ApMV) and Myrobalan latent ringspot virus (MLRSV). Similarly, ten trees of each sweet cherry orchard were sampled and tested for the presence of PDV, PNRSV, ApMV, ACLSV, PPV, Arabis mosaic virus (ArMV), Cherry leaf roll virus (CLRV), Raspberry ringspot virus (RpRSV), Strawberry latent ringspot virus (SLRSV) and Tomato black ring virus (TBRV) by serologic assays. Additionally, a few sweet cherry trees suspected to be infected by Little cherry virus-1 (LChV-1) were tested by molecular assay. Unexpectedly, no plum orchards were found to be free of PPV. The average level of PPV infection was 32%. PNRSV occurred in 8.1% and PDV in 1.2% of sampled plum trees. Four out of ten viruses were detected in sweet cherry sampled: PDV (3.6%), ACLSV (0.9%), RpRSV (0.9%) and TBRV (0.9%). No infection with ACLSV, ApMV and MLRSV in plum and PPV, PNRSV, ApMV, ArMV, CLRV, SLRSV and LChV-1 in sweet cherry was detected. Mixed infections occurred at 4.8% in plum, and at 0.9% in sweet cherry trees sampled. The average occurrence of viruses in plum and sweet cherry orchards surveyed in Transylvania was determined at 41.3%, and 6.3% respectively. Overall results revealed a critical situation especially in regards to PPV infections making the success of fruit production in the most surveyed plum orchards quite problematic. Virus infections level in the younger sweet cherry orchards were significantly lower.

The experiment aimed to evaluate some of organic products within a treatment scheme against Eurytoma schreineri Schreiner., on two different plum varieties: Stanley and Reine Claude d’Althan. An experimental scheme of organic treatments by using seven organic products with insecticidal effect was developed and used for evaluation in the field. There were three variants taken into account: organic, conventional and untreated, used as control. Each variant consisted of eight trees belonging to Stanley and Reine Claude d’Althan cvs., four trees for each variety. The frequency occurring of Eurytoma schreineri was evaluated along two consecutive years (2019-2020). Overall results confirmed the sensitivity of Stanley cv. to Eurytoma. schreineri. On the other hand, the results showed that the organic scheme developed was unsatisfactory and there is a risk of considerable losses for farmers who opt for this kind of scheme.

Four young plum orchards from Iaşi county, two of these established by using propagated material in Romania, and the other two with material from Austria, Czech Republic and Netherlands, were surveyed by visual observation of viral symptoms. Then, trees were sampled and tested for the presence of six viruses (PPV, PDV, PNRSV, ACLSV, ApMV and MLRSV) by serologic assays. A high rate of PPV infection (78% and 79%, respectively) was determinated in the two orchards established with planting material propagated in Romania, and a rate of 5% PDV infection was found in one of them. A rate of 2.5% PPV infection was determined in the orchard established with propagated material in Austria and Czech Republic, and no PPV infected tree was found in the orchard set up with material propagated in Netherlands. The infections with PNRSV, ACLSV, ApMV and MLRSV were not detected in the four orchards surveyed.

The plum seed wasp (Eurytoma schreineri Schr.) is a polyphagous pest that can cause significant damages to the plum crop. A transgenic plum variety, resistant to Plum pox virus, was evaluated to the attack frequency of E. schreineri in the context of reduced number of insecticide treatments against aphids, in comparison with two conventional plum varieties. The most affected variety by plum seed wasp, for two consecutive years, was ‘Stanley’, followed by ‘Reine Claude d’Althan’, and then ‘HoneySweet’ transgenic plum. The differences between variants were statistically assured.

The European plum (Prunus domestica L.) is one of the most important cultivated species among fruit trees in the world, and the dominant in Romania. Regarding the development of new plum cultivars derived from Prunus domestica, the following characteristics are taken into consideration most of the time: high yield performance, good quality fruits and last but not least, the resistance to PPV. “HoneySweet” is a transgenic clone of Prunus domestica transformed with Plum pox virus coat protein gene making it highly resistant to the virus. This study presents preliminary results on the chemical composition of HoneySweet transgenic plum and two conventional ones: Reine Claude d’Althan and Stanley. The most important nutritional factors were determined. HoneySweet had balanced individual carbohydrates content but lower soluble solids in comparison with the two conventional cultivars. Total lipids content in HoneySweet fruits was similar to Stanley, higher than in Reine Claude d’Althan. HoneySweet is distinguished by the highest total protein content. Similar amounts of magnesium and calcium were recorded in the three varieties. Overall, our preliminary results revealed that the quality and nutritional value of “Honey Sweet” genetic engineered plum is in the range of other valuable plum cultivars.

Sweet cherry (Prunus avium L.), originated around the Caspian and Black Sea, is an important fruit tree species of economic interest, and hence, breeding and conservation are requested (. Genetic analysis at the molecular level can be used effectively to study molecular polymorphism existing between intraspecific and interspecific tree species and phylogenetic relationships between them and their hybrids. The purpose of this study was to characterize and determine genetic relationships among the sweet cherry native genotypes belonging to Fruit Research & Development Station Bistrita, Romania, using RAPD markers. To eliminate the existence of possible synonyms from national romanian collection, we collect four Van cultivars, from four different national collection. For molecular analysis of the 16 varieties of sweet cherry were considered 13 RAPD primers selected from the literature. They were later used to determine the genetic variability at the molecular level using PAST program, and the dendrogram was generated based on Jaccard’s genetic distance. The dendrogram constructed by PAST software. The quantity and quality of the DNA obtained was suitable to achieve PCR amplification step. Only seven out of the 13 RAPD primers have generate polymorphic bands. The rest of seven were monomorphics. The most polymorphic primer was OPB10 which generated 11 bands from which 100% were polymorphic.Seven RAPD primers generated a high level of polymorphism which allowed to divide these cherry varieties into two groups according to their genetic geographical origin and the pedigree.

Plum pox virus (PPV) is considered the most destructive viral pathogen of stone fruits. Although PPV is widespread in all plum growing areas from Romania and causes serious yield losses, little is known about the virus variability. For this reason we investigated 100 PPV isolates collected from 13 different plum orchards in the Transylvania - Romania. PPV detection was made by DAS-ELISA and by IC-RT-PCR. PPV strains were serologically determined by TAS-ELISA using PPV-D and PPV-M specific monoclonal antibodies. Molecular strain typing was done by RT-PCR targeting three different genomic segments corresponding to (Cter)CP, (Cter)NIb/(Nter)CP and CI. RFLP analysis was used to distinguish the two major strains, D and M based on a RsaI polymorphism located in (Cter)CP. All PCR products targeting (Cter)CP and 10 PCR products spanning the (Cter)NIb/(Nter)CP were sequenced. All PPV isolates typed as PPV-M by serological analysis and by molecular differentiation in the genomic region corresponding to (C-ter)CP proved to be PPV recombinant (PPV-Rec) when the molecular analysis were performed in the region corresponding to NIb/CP. Sequencing confirmed a high similarity with different sequences of PPV-Rec previously reported. All these recombinant isolates share the same recombination breakpoint and conserve the DAG motif, which is considered essential for aphid transmission. Overall results provided that in Transylvania the predominant strain is PPV-D, followed by PPV-Rec which shares the CP gene with M strain and, therefore, it is serologically detected as PPV-M with M-specific monoclonal antibodies. In this big plum growing area, mixed infections (PPV-D+PPV-Rec), which might generate additional variation by recombination, are also frequent.

To assess the durability of resistance to PPV of HoneySweet transgenic plum harbouring plum pox virus (PPV) capsid gene, a new field trial was recently established in Romania at Fruit Research & Development Station Bistrita. Stanley and Reine Claude d’Althan cvs. are used as control. PPV inoculum source is secured within the experimental plot. PPV monitoring was made by visual observation of symptoms development on leaves and by serological (DAS-ELISA) and molecular (IC/-RT-PCR) testings. Three years after planting PPV was observed and detected only on Stanley. 'HoneySweet' and Reine Claude d’Althan cultivars remained PPV free.