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Published By Czech Academy Of Agricultural Sciences

1805-9341, 1212-2580

2021 ◽  
Vol 58 (No. 1) ◽  
pp. 31-39
Author(s):  
Mustafa Usta ◽  
Abdullah Güller ◽  
Hikmet Murat Sipahioglu

Phytoplasma-like symptoms of leaf yellowing and calyx malformation were observed in eggplant (Solanum melongena L.), upward leaves and fruit malformation in pepper (Capsicum annuum L.), and aerial tuber formation in potato (S. tuberosum L.) during the survey performed in the late season (August to September) of 2015 and 2016 in Van province (Turkey). A total of 100 samples were tested by nested-PCR using universal primer pairs to assess the sanitary status of the solanaceous crops and to characterise the phytoplasma isolates. Among them, seven samples resulted in a 1.25 kb DNA fragment, and five (two eggplants, two peppers, and one potato) were molecularly characterised (Accession No.: KY579357, KT595210, MF564267, MF564266, and MH683601). BLAST and the virtual restriction fragment length polymorphism (RFLP) analysis of 16S rRNA genes revealed the presence of two distinct phytoplasma infections in solanaceous crops: ‘Candidatus Phytoplasma trifolii’ a member of the clover proliferation group (16SrVI) and subgroup A and ‘Candidatus P. solani’ a member of the stolbur group (16SrXII) and subgroup A. The virtual RFLP analysis and calculated coefficients of RFLP pattern similarities further revealed a remarkable genetic diversity among the ‘Candidatus P. solani’ isolates infecting pepper (similarity coefficient of 0.90) and eggplant (similarity coefficients of 0.98 and 1.00) at the same geographical area. This is the first report of the natural occurrence of ‘Candidadtus P. trifolii’ in potato from the Eastern Anatolia region, Turkey.


Author(s):  
Đura Nađ ◽  
Dušan Marinković

The pear psyllid [Cacopsylla pyri (L.), (Hemiptera: Psyllidae)] represents one of the most economically significant pests of pear in Serbia and worldwide. It causes direct damage throughout feeding on young stems and leaves, but also creates favourable conditions for the development of plant diseases. In this article susceptibility of C. pyri to spirodiclofen, spirotetramat, and their combinations with foliar fertilizer (carboxymethyl cellulose-boron, CMC-B) was investigated in order to assess their efficacy. Experiments were conducted in accordance with standard OEPP/EPPO methods, in field trials on two localities in the Republic of Serbia (Kula, Vrbas), during 2020/21. Results of the field trials indicate good efficacy for all variants in pear psyllid control in pear orchards. The high efficacy of spirodiclofen (87.4–95.4%), spirotetramat (82.5–91.8%), spirodiclofen + CMC-B (90.3–99.8%), spirotetramat + CMC-B (89.5–96.8%) was achieved at both localities seven days after treatment during 2020/21 field trials. Also, it can be concluded for examinations 14 days after treatment, where the efficacy of spirodiclofen (84.9–92.0%), spirotetramat (81.2–91.7%), spirodiclofen + CMC-B (88.9–97.5%), and spirotetramat + CMC-B (82.3–92.5%) was high at both of investigated localities. Based on the obtained results it can be concluded that the high efficacy of the researched insecticides is a good indicator of C. pyri susceptibility in pear orchards.  


Author(s):  
Sayma T. Nira ◽  
Md. Farhad Hossain ◽  
Nur Uddin Mahmud ◽  
Oliul Hassan ◽  
Md. Tofazzal Islam ◽  
...  

  This study aimed to isolate and characterise the pathogen associated with Alternaria leaf spot on broccoli and to evaluate the inhibitory effects of fungicides against it. We isolated and identified the fungal pathogen as Alternaria sp. using morphological and cultural methods. Based on the aligned sequences of the internal transcribed spacer (ITS) and molecular phylogenetic analysis by the neighbour-joining method, the isolates (Ab1 and Ab2) were confirmed as Alternaria alternata. The conidia of the isolates were dark brown, cylindrical, obclavate to muriform. The conidiophores were olivaceous brown, septate, and branched. The conidial morphology of the isolates ranged from 52.4–92.4 × 10–20 μm with 2–6 transverse and 0–3 longitudinal septa. Both isolates yielded positive results in the pathogenicity test on broccoli leaves by developing brown and circular spots with concentric rings on the leaves surrounded by yellow halos. The culture studies revealed that the maximum growth of the pathogen was obtained at 30 °C and pH 6.0. Tilt 250 WC showed the highest potential in suppressing the mycelial growth of the A. alternata in vitro at a concentration as low as 50 µg/mL. The results from this study contributed to the positive identification of the pathogen and characterised A. alternata as a destructive pathogen of broccoli which may be successfully controlled by the fungicide Tilt.  


Author(s):  
Jayant Yadav ◽  
Poonam Jasrotia ◽  
Ajay Kumar Bhardwaj ◽  
Prem Lal Kashyap ◽  
Sudheer Kumar ◽  
...  

 Nanotechnology is a rapidly evolving field that has the potential to revolutionise food systems and counter the present-day challenge of food security. It envisages taking agriculture from the era of indiscriminate natural resource use and environmental degradation to the brave new world of advanced systems with enhanced material use efficiency and targeted applications to reduce crop losses caused due to abiotic-biotic stresses as well as to give due considerations to the environment. To manage plant diseases and insect pests, pesticides are inevitably used in agriculture. However, the higher dosage of these chemicals on a per hectare basis has resulted in many environmental and health hazards. To tackle the conventional pesticide related issues, a new field of science called nanotechnology has led to the development of nanopesticides that have less active ingredients, but better efficiency. The nanopesticides contain the carrier molecule or the active nanosized ingredient with a very high surface area to the volume property that provides them unique exploitable-advantages. Several formulations, viz., nanoemulsions, nanosuspensions, nanogels, metal compound-based nanopesticides, have been developed for different modes of action and vivid applications. The biggest advantage comes due to the small size of the particles that help in properly spreading the ingredients on the pest surface and, thus, producing a better action than conventional pesticides. The use of nanoparticles in the form of nanopesticides, nanofertilisers, and nano delivery systems is on the increase day by day due to their higher efficiency and reduced dosage requirements. However, human beings and other organisms are also getting exposed to the nano-entities during the application or afterwards. The interactions of these engineered nano-entities with biological systems are relatively unknown thus far. Therefore, before their wider usage in crop production and protection, a better understanding of their interactions, and adverse effects, if any, is also crucial for a sustainable transition.  


Author(s):  
Richard Osei ◽  
Chengde Yang ◽  
Lingxiao Cui ◽  
Lijuan Wei ◽  
Mengjun Jin ◽  
...  

Bacterial antagonists are effective as an alternative to synthetic bactericides in the control of potato soft rot. The use of bioagents reduces the application of synthetic bactericides, which are harmful to humans and the environment. However, the mechanisms of some bioagents, such as some fungi and bacteria, are not yet understood. This paper reviews the current situation of potato soft rot, biological controls, antagonistic bioagents and their mechanisms, application strategies and future directions in today’s agriculture. These mechanisms include mycoparasitism, competition, rhizosphere colonisation, synthesis and release of metabolites. Bioagents increased the defensive system of plants by increasing the antioxidants genes, such as superoxide dismutase, peroxidase (POD) and catalase (CAT), and eventually increased the plant growth and yield production.  


Author(s):  
Maria Iwebor ◽  
Tatiana Antonova ◽  
Nina Araslanova ◽  
Svetlana Saukova ◽  
Yulia Pitinova ◽  
...  

Sunflower downy mildew caused by Plasmopara halstedii (Farl.) Berl. et de Toni is a destructive and widespread disease. More than 50 races of P. halstedii have been recorded worldwide. In 2020, in the Russian Federation (Zernogradsky district, Rostov region), a globally new race 337 was identified for the first time. The pathogen was identified on the plants of a foreign sunflower hybrid bearing the resistance gene Pl<sub>6</sub>. According to the five-digit racial nomenclature, its virulence profile was determined as 337 53. It is the first P. halstedii race recorded in the Russian Federation that simultaneously infects all differential lines of the 3<sup>rd</sup> triplet, i.e., HA-R4, HA-R5 and HA-335. The sunflower lines RHA-274, 803-1, PSC8, RHA-419 and RHA-340 were resistant to it. All the collected isolates of the new race were susceptible to the fungicide mefenoxam.    


2021 ◽  
Author(s):  
Ismail Poyraz

Myclobutanil is a chemical pesticide commonly used in the production of some vegetables and fruits like greenhouse peppers, grapes, and apples. The aim of this study was to investigate the genotoxic and cytotoxic effects of myclobutanil fungicide on the Allium cepa plant, the model organism. Randomly amplified polymorphic DNA and inter simple sequence repeat-PCR techniques were performed on the DNA of A. cepa exposed to the different myclobutanil doses and time periods. The nucleus anomalies and abnormal anaphases were investigated using a light microscope. PCR analyses showed that myclobutanil causes some DNA sequence changes on the onion genome depending on the increase in the fungicide dose and exposure time. It was determined that myclobutanil has a serious genotoxic effect, even in low doses like 25–50 ppm.  


Author(s):  
Kasem Soytong ◽  
Jiaojiao Song ◽  
Somdej Kanokmedhakul

Metabolites of Emericella nidulans (EN) were separated by chromatographic methods from crude hexane included emericellin and sterigmatocystin, while crude ethyl acetate found demethylsterigmatocystin. These metabolites proved to be antagonistic to Magnaporthe oryzae, the causal agent of rice blast. Crude extracts and nano-particles derived from EN inhibited M. oryzae. The ethyl acetate crude extract derived inhibited M. oryzae with an effective dose (ED<sub>50</sub>) of 66 μg/mL. The nanoparticles showed better inhibition of M. oryzae than crude extracts at low concentrations. Nanoparticles, namely from crude ethyl acetate, crude methanol and crude hexane of EN were active against M. oryzae with ED<sub>50</sub> of 4.2 μg/mL, 4.5 μg/mL, 8.9 μg/mL, respectively. It detected sakuranetin (rate of flow value is 0.09) in nano-EN treated rice leaves. These nanoparticles inhibited M. oryzae and acted as a new elicitor to induce immunity.


Author(s):  
Sandor Keszthelyi ◽  
Tamás Sipos ◽  
Ádám Csóka ◽  
Tamás Donkó

The cypress jewel beetle Lamprodila (Palmar) festiva is a wood-boring pest posing a major threat to the phytosanitary conditions of several coniferous trees. Its unprecedented European expansion has triggered serious plant protection concerns in several new habitats. Parts of Chamaecyparis lawsoniana injured by L. festiva were collected and analysed by computed tomography in order to study the dimensions of the cavities caused by L. festiva larvae as well as the larval positions. It is concluded that computer tomography representing a non-invasive approach is a promising tool for the visual depiction of the position and the physical parameters of the cavities formed. According to our experimental data, the penetration into the cypress caused by larvae and, inherently, its depth depends on the diameter of the branch. Additionally, the developing larvae appeared to keep distance from each other, which also depended on the diameter of the attacked branch. Our approach provides new data to the biological traits of the species. The main benefit that our imaging method furnishes is the exact, stress-free measurement method of the hidden developing stages. Its additional advantage is the indirect pest identification, which is based on the predetermined pest-specific damage characters.


2021 ◽  
Vol 57 (No. 4) ◽  
pp. 279-288
Author(s):  
Jose Ignacio Ruiz de Galarreta ◽  
Alba Alvarez-Morezuelas ◽  
Nestor Alor ◽  
Leire Barandalla ◽  
Enrique Ritter

The oomycete Phytophthora infestans is responsible for the disease known as late blight in potato and tomato. It is the plant pathogen that has caused the greatest impact on humankind so far and, despite all the studies that have been made, it remains the most important in this crop. In Spain during the last years a greater severity of the disease has been observed in both, potato and tomato, probably due to genetic changes in pathogen populations described recently. The aim of this study was the characterization of the physiological strains of 52 isolates of P. infestans obtained in different potato-growing areas in Spain. For this purpose, inoculations on detached leaves were performed in order to determine compatibility or incompatibility reactions. A total of 17 physiological races were found. The less frequent virulence factors were Avr5 and Avr8. By studying the epidemiology of the pathogen, a specific breeding program for late blight resistance can be implemented.


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