نشریه گیاه پزشکی کاربردی
سال دهم شماره 2 (پیاپی 30، اسفند 1400)

One of the greatest biotic stress reducing potential yield in chickpea is Ascochyta blight caused by Ascochyta rabiei Pass. (Labr.) which is distributed worldwide. Due to its severity and to decreasing the environmental biological impact of chemical control, research on natural compounds like plant essential oils would be a helpful step in the disease management. In this study, the antifungal efficacy of essential oil of eight plants including thyme, savory, pennyroyal, mint, tarragon, fennel, cumin and ajwain at 5 concentrations in 3 replications under complete random design was evaluated. Characteristics like mycelial growth inhibition (MGI), inhibitory minimum concentration (IMC) and speed of colony growth after treatment were studied under laboratory condition. Pathogenicity index was studied under greenhouse condition by the selected plants through laboratory tests in comparison with the fungicide Rovral-TS and intact and infected controls. Result showed that at greenhouse, thyme and fennel showed the most inhibitory index in comparison with the rest six plants. Fennel showed the most effective MGI against Ascochyta blight at laboratory. The result of the present study show that thyme and fennel would be great options to be considered in the integrated management programs of chickpea Ascochyta blight.

Today mushroom cultivation has become one of the money making sources in industry and trade all around the world. Due to its production system, this rich nutritional product is under the attack of several pest agents. In this study, the arthropods existing in mushroom cultivation systems was collected through two production stages, spawning and casing from six production units in Zarandieh county, Marakazi province. Samples were separated by Berlese funnel and retained in Ethanol 70%; then identified by certified resources. The abundance of each species was caulcuated and the mean density of different species were compared statistically. In total, 1814 samples belonging to different orders of Insecta and Acari were collected. 790 samples were collected through spawning and 1024 samples through casing. Collected arthropods belonging to 15 species under 14 genera and 11 families. Tyrophagus putrescentiae was the most abundant species (18.91 ± 2.06%) with significant difference. Megaselia halterata (14.39± 1.88 %) and Lycoriella auripila (11.87 ± 0.47) were the most abundant species, subsequently. Among the collected species, two predators, Atheta coriaria and M. galber were identified. Most of the collected species were saprophagous and infected compost would be a possible way to introduce them into the mushroom cultivation systems. Samples like M. halterata, Megaselia scalaris, L. auripila, Colbodia fuscipes and T. putrescentiae were mycophagous and could make direct damage to mushroom product. Compost sterilizing would be an effective way to eliminate pest arthropods in mushroom cultivation systems.

European red mite Panonychus ulmi (Koch) is one of the most important pests in orchards including apple trees, across different parts of Iran. The effectiveness of the new acaricide acequinocyl was tested on the European red mite of apple tree in three provinces of West Azerbaijan, East Azerbaijan and Khorasan-e Razavi in 2016. Effect of acequinocyl 1 and 1.25 ml/lit was compared with spirodiclofen 0.5 ml/lit, phenazaquin 0.5 ml/lit, and control (watering). In order to determine the effectiveness of the treatment, the number of live mites on host leaves was recorded at one day before and 3, 7, 14 and 21 days after spraying. The percentage of efficiency of these treatments was calculated using Henderson-Tilton formula and the Analysis of Variance was done with SAS statistical software. In West Azerbaijan, there was a significant difference between treatments at 3 and 7 days and acequinocyl 1.25 ml/lit and phenazaquin were most effective in 3 days (97%). In East Azerbaijan, at 3 days, all acaricides showed more than 73% effectiveness. On the 21st day after spraying, spirodiclofen and acequinocyl (1 ml/lit.) had the highest effect compared to the other treatments (75.27% and 65.07% respectively). In Khorasan-e Razavi, all treatments were more than 93% effective at 14 days and the effect of acequinocyl 1.25 ml/l and phenazaquin treatments were similar (100%) on day 3. The results showed that acequinocyl at the both concentrations (1 ml/lit and 1.25 ml/lit) was effective in controlling European red mite on apple and could be a good alternative to older acaricides.

Growing of cucumbers in the form of a greenhouse in Iran has expanded a lot in recent years. In this study, the effect of Denai thyme essential oil and two fungicides, fustil aluminum and metalaxyl-mancozeb, were studied for greenhouse cucumber plant dieback disease caused by Phytophthora pseudofungus. In the greenhouse test, the effects of the mentioned treatments on the activity of peroxidase, catalase and phenylalanine ammonia-lyase enzymes in cucumber plants infected by Phytophthora sp. was contaminated, it was measured. The results of the effect of different treatments on the defense mechanisms of the cucumber plant showed that the highest activity of the three enzymes peroxidase, catalase and also the enzyme phenylalanine ammonialyase was related to the treatment of the infected cucumber plant treated with a concentration of 150 ppm fustil aluminum fungicide, which was on the sixth day after Contamination with the pathogen, the activity of the peroxidase enzyme reached ΔOD/Min/mg protein of 1.95. The trend of the activity of all three enzymes was increasing until the sixth day and then decreasing, so that on the tenth day after infecting cucumbers with the pathogen, the activity of this enzyme decreased in fustil aluminum treatment and reached 29/ΔOD/Min/mg protein. 1 receipt. The treatment using Fustil aluminum fungicide on all the days of sampling compared to all other treatments had a significant difference in terms of enzyme activity level. On all sampling days, enzyme activity in metalaxyl-mancozeb treatment was significantly higher than control. On the 10th day after sampling, the activity level of all three enzymes decreases in all treatments compared to the 8th day, but the process of enzyme activity in different treatments is the same as the rest of the days. In other words, all the treatments are able to increase the activity of this enzyme compared to the control, but more importantly, this enzyme is also affected by the days of sampling. The results showed that Danai thyme was able to induce defense enzymes against the pathogen on all sampling days. In other words, the essential oil of this plant can affect the defense mechanisms of the plant along with the chemical inducers, and in this way, reduce the damage caused by pathogens to the plant.

Fusarium wilt on cucumber caused by Fusarium oxysporum f. sp. radicis-cucumerinum is an important and common disease of cucumber in Iran. In this study, differences of pathogenicity between several isolates and their impact were assessed on the plant growth parameters. The pathogenicity of 50 isolates collected from cucumber plants with wilting and yellowing symptoms from different geographic areas of Iran, were examined on cucumber, Negin cultivar. The inoculated and control plants were placed at 25°C for 14 days. Disease severity and the weight of root and crown were measured 10 days post-inoculation. Studied factors showed significant difference at 1% level among isolates of F. oxysporum f. sp. radicis-cucumerinum. The maximum percentage of disease was observed in plants treated by F-111-2, F-133-2 and H8; while the highest disease severity induced in plants treated by F-111-2, F-160-12 and F-111-5. F-111-5, F-160-12 and F-121-4 incited the most decrease in root weight. The crown weight decrease in the presence of F-160-12, F-121-4 and F-111-10 isolates of Fusarium oxysporum f. sp. radicis-cucumerinum correspondingly. Totally, due to the results, it could be concluded that f-160-12 can be considered as the most severe pathogenic isolate.

With the advent of molecular biology knowledge, the function of many genes was determined to some extent by studying the phenotype of mutated genes (forward genetics) and a hint of the function of the desired gene was obtained. But with the invention of large-scale DNA sequencing, thousands of genes were identified in various organisms without their function being known. Today, by using the knowledge of reverse genetics, which is currently the most efficient method of evaluating the role and function of genes, the function of many sequenced genes has been determined. Nowadays, the sequence of many genes of living organisms is known, but the phenotype of these sequences often remains unknown. Therefore, reverse genetic strategies have attracted the attention of many genetic researchers, although these strategies do not have the same application in all organisms. Reverse genetics is a technique to discover the function of genes that have been sequenced by DNA sequencing technology. In fact, it is a study method in genetics in which the function of genes is done by studying organisms whose function of genes has been changed. In the past, genetic studies were carried out by studying mutant phenotypes, but now with the progress in biological sciences, researchers are able to attribute phenotypic characteristics to a specific gene.