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'Candidatus Phytoplasma prunorum' is causing ever increasing economic losses through the decline of apricot trees in European countries, e.g., Hungary. In this study, the pathogen was identified from plant tissues and insects by nested-PCR. The insect species were identified via morphology and molecular methods. The incidence of the pathogen was 29.6% in randomly selected apricot trees. Most of the infected trees with symptoms died within a year. These results show that phytoplasma is significantly present and causes damage in the investigated plantations. The only known insect vector of this phytoplasma is the plum psyllid, Cacopsylla pruni, which was regularly encountered in the sampled apricot orchards and in their surroundings. In a two-year study, several adults among the sampled specimens were observed to be infected by the pathogen. This observation further confirms the role of the plum psyllid in vectoring the phytoplasma. All the sampled plum psyllid adults belonged to the 'B' biotype. Besides C. pruni, Cacopsylla crataegi was abundant in the samples. Several adults of the latter species were also infected by the pathogen 'Ca. Phytoplasma prunorum'. The rates of occurrence of this phytoplasma in male and female adults of the two psyllid species appeared to be similar. The examined C. crataegi individuals showed genetic differences from each other and from specimens included in a previous investigation. [ABSTRACT FROM AUTHOR]

The aim of our research was to adapt Chuine's unified model to estimate the beginning of blooming of three apricot cultivars ('Ceglédi bíborkajszi', 'Gönci magyar kajszi', and 'Rózsakajszi C.1406') in Hungary in the time period 1994–2020. The unified model is based on the collection of chilling and forcing units. The complexity of the model lies in the high number of parameters necessary to run it. Following the work of other researchers, we reduced the number of relevant model parameters (MP) to six. In order to estimate the six MPs, we used a simulated annealing optimization method (known for being effective in avoiding getting stuck in local minima). From the results, we determined the local optimum of six MPs, and the global optimum parameter vector for three apricot cultivars. With these global optimum parameter vectors, the beginning of blooming could be estimated with a root-mean-square error (RMSE) of less than 2.5 days, using the knowledge of the daily mean temperature in the time period 1994–2020. [ABSTRACT FROM AUTHOR]

Apricot aphid, Myzus mumecola (Matsumura) (Homoptera: Aphididae), was recorded as a new pest of apricot in Hungary in the spring of 2020. Identification was based on morphological and genetical (mitochondrial COI region) characteristics. M. mumecola most likely arrived in Hungary in the last 2–3 years and has quickly become a widespread pest causing significant damage to young apricot trees. Colony development, damage and differences in susceptibility between cultivars are described. The presence of Plum pox virus in M. mumecola samples was detected, and all isolates belonged to the PPV-D subgroup. Illustrations of the most important diagnostic characters of M. mumecola are provided. [ABSTRACT FROM AUTHOR]

The epidemiology of 'Candidatus Phytoplasma prunorum' was studied in Austria and Hungary from 2014 to 2018. Testing of root samples showed average infections rates of 61 and 40% of the Austrian Prunus spinosa and Prunus domestica spp. insititia samples, respectively. In Hungary, on average 21% of the P. spinosa and 13% of the feral Prunus cerasifera samples were infected. The pathogen was found in 18 out of 19 apricot orchards and PCR positive Cacopsylla pruni were observed at 11 out of 17 sampling locations in both countries. In cage experiments with C. pruni remigrants successful pathogen transmission to Prunus armeniaca, P. domestica and P. spinosa seedlings in budding and foliated developmental stages was recorded, an inoculation access period of 4 hr was sufficient for transmission. A field experiment with ungrafted apricot seedlings planted in 2012 and 2014 indicated a prominent role of the insect vectors for disease spread. In 2017, 40 and 28% of the trees planted in 2012 and 2014, respectively, were infected. Molecular characterisation based on the genes aceF and imp allowed the discrimination between 10 phytoplasma types in apricots. Around 70% of the phytoplasma types in apricots were also common in P. spinosa, in P. domestica spp. insititia and in remigrant C. pruni pointing to a possible pathogen exchange by insects between wild and cultivated Prunus spp. For disease control, vector management over the entire flight period of the remigrants seems necessary; when selecting active compounds, the short inoculation access period of not more than 4 hr should be considered. [ABSTRACT FROM AUTHOR]

During July 2012, a severe unusual disease symptom was observed on young shoots on apricot (Prunus armeniaca 10/13 hybrid) in the city of Pomáz, near Budapest. The naturally infected shoots showed typical symptoms of fire blight including terminal shoots with brown to black necrotic lesions. Symptoms were the same as fire blight symptoms reported from other hosts and locations. The first occurrence of fire blight on an apricot tree in Europe was recorded in Czech Republic in 2011. Samples of the leaves and shoots with symptoms were macerated and spread on King's medium B. After 24 hours of incubation at 26 °C, bacteria morphologically similar to E. amylovora were detected. Isolate induced hypersensitive reaction on tobacco (Nicotiana tabacum L. 'White Burley') leaves. Biochemical test was also used for identification, and the result of API 20E kit (Biomérieux, Marcy l'Etoile, France), demonstrate that the bacterium belongs to Enterobacteriaceae family. A pathogenicity tests were positive on young apricot shoots and immature fruits. For molecular identification of the pathogen the 16S rDNA region was amplified from isolate Ea-ApricotPo1 with a general bacterial primer pair (63f forward and 1389r reverse). The PCR products were cloned into a pGEM T-Easy plasmid vector (Promega, Madison, WI USA) and were transformed into Escherichia coli DH5α cells. A recombinant plasmid (2A2.5) was sequenced by M13 forward and reverse primers. The sequence was deposited in GenBank (Accession No. HF546214) and showed 99-100% sequence homology with a number of E. amylovora isolates, including type strain FN666575 with 100% similarity. On the basis of the symptoms, colony morphology, biochemical tests, and 16S rDNA sequence homology, the pathogen was identified as E. amylovora. This is a first record of a natural outbreak of fire blight on apricot in Hungary. [ABSTRACT FROM AUTHOR]

Like all phenological processes, microsporogenesis is mainly determined genetically, but its phenotypical expression is greatly influenced by environmental factors, particularly the temperature. During the 3-year experimental period, the process of microsporogenesis was examined in eight apricot cultivars originated in North America and in Romania. The Hungarian cultivar 'Gönci magyar kajszi' was used as the control. Based on the results it was possible to rank the cultivars in terms of their microsporogenesis schedule. The same order was found in all three years. This order also indicates the yield reliability of the cultivars. Endodormancy ended between January 10th and 25th in the buds of the earliest cultivar 'Pinkcot', but not until February 5-10th in the latest cultivar 'Harlayne'. Three of the cultivars had faster flower bud development than the control, in the order 'Pinkcot', 'Orange Red' and 'Harcot'. Growing these cultivars thus involves greater risk than for 'Gönci magyar kajszi' in Hungary, due to their rapid winter flower bud development. Some cultivars found to have slower flower bud development than 'Gönci magyar kajszi'; 'Litoral', 'Harogem', 'Comandor', 'Sirena' and 'Harlayne' -- thus these cultivars can be grown more reliably. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate changes in (i) nitrogen (N2) fixation, (ii) netnitrification, and (iii) denitrification potentials under different land uses in a small catchment(21 km2) in Balaton Upland, Hungary. Soil samples were collected from the following sixland use types in three replicates: mixed forest (oak and wattle), forest (oak), grapevine,arable land (winter wheat), orchard (apricot), and grassland. All nitrogen cycling experimentswere carried out under dark conditions in a temperature-controlled laboratory environment.The investigations were implemented under three temperatures 10, 20, and 30 ∘C to representthe typical vegetation season temperature range in the investigated catchment. Potentialnitrogen (N2) fixation was measured as ethylene (C2H4) production from acetylene (C2H2)reduction. Potential denitrification rates were measured using the acetylene blocktechnique.Potential N2 fixation was positively correlated with temperature or no change was observed.Rates decreased as temperature was increased from 10 to 20 ∘C in the cases of arable,orchard, and grassland, while did not change in the case of the forest samples. When thetemperature was increased to 30 ∘C, the N2 fixation potentials also increased significantly(p < 0.017) compared to 10 to 20 ∘C. When investigating the net nitrification of the soils,we found negative correlation with temperature increase, the highest values wereretrieved at 10 ∘C (average net nitrification was 0.2793 nmol N g−1 wet weight soilhr−1), while the lowest at 30 ∘C (average net nitrification was −0.0681 nmol N g−1wet weight soil hr−1). Potential denitrification values were the highest at 20 ∘C.Forest soils did not show substantial differences in potential denitrification rateswhile varying temperatures; however, within land uses all values retrieved at theinvestigated temperatures were significantly different (p < 0.0174). Overall, wefound that land use types can significantly influence the soils’ nitrogen cyclingprocesses, especially when fertilizer amendment is regularly applied. Potentialnitrogen cycle components under different land use types, which are less influenced byanthropogenic activities (e.g. forest soils), were found to be less sensitive to temperaturechanges. [ABSTRACT FROM AUTHOR]

The article presents the high incidence of Plum pox virus (PPV) in fruit trees in Hungary. The article focuses on a survey to determine PPV infection in ornamental Prunus species. The article also discusses the presence of PPV-C strain in cherry trees, D strain in most of the infected plants and M strain in certain plants of P. blireana and P. glandulosa.