نشریه گیاه پزشکی کاربردی
سال پنجم شماره 2 (پیاپی 18، شهریور 1395)

Fusarium oxysporum f. sp. nicotianae, the causal agent of tobacco fusarium wilt, is one of the important agents that distributed worldwide and cause yield losses in tobacco growing countries. Control of this pathogen are accomplished through the use of chemical control, biological control, use of plant extracts, resistant cultivars and etc. The objective of this study was to evaluation of infections status of this disease in the tobacco fields of Golestan province. 45 tobacco fields in the five different villages of Gorgan region (Valeshabad, Taghartappeh, Jafarabad, Nodehmalek and Ghorogh) and the four different villages of Aliabad region (Baraftan, Pichakmahaleh, Elazman and Fazelabad) were selected in 2016 year. From the beginning of disease symptoms appearance, weekly surveys were done from fields and amount of disease incidence percent was recorded during the infection period. Statistical analysis were done using Stat Graphics Centurion XVI software. The results of this research showed that the based on the highest disease incidence there were no significant differences between regions, but there were significant differences (P<0.001) among fields. One field with disease incidence 48.2% in Valeshabad was highest disease incidence and combined Valeshabad with disease incidence 31.16% had the highest infection and Taghartappeh with disease incidence 18.5% had the lowest infection. Based on areas under disease progress curves, there no significant differences between regions, but there were significant differences (P<0.001) between fields. One field with under disease progress curves 1816.2 in Valeshabad had highest. In combined Valeshabad with 2700 had highest disease progress curves and Taghartappeh with 971.8 disease progress curves had the lowest. The results of this study show that Fusarium wilt disease of tobacco in all regions in Golestan province (Gorgan and Aliabad) with different rate of expansion.

Beta-glucosidase (βglu) is widespread in all plants, animals, fungi and bacteria. βglu catalyzes the hydrolysis of β-1,4 bonds to terminal non-reducing residues in beta-D-glucosides and oligosaccharides, with release of glucose. Thus these enzymes are named based on the released monosaccharides. In current research, the bioinformatics analysis of βglu was performed in thirteen different insect species from different families. The primary and secondary structural analyses of thirteen species of insects were investigated by ProtParam and SOPMA tools. TMHMM and SignalP server were used to identify transmembrane domains and signal peptide in each species, respectively. The number of amino acids, isoelectric point, molecular weight, instability index, GRAVY and aliphatic index were identified in each sample and compared with each other. According to the results, none of the species had transmembrane domain but Trachymyrmex cornetzi. Also signal peptide just was observed in Acyrthosiphon pisum, Bombyx mori and Cephus cinctus. Based on the structural analysis, there are a lot of similarities among βglu protein in different insect species; however there were some differences among some insects. The obtained data provides background of digestive enzyme studies like βglu and their structural identification in insects.

Damping-off Cucumber disease due to Phytophthora species is one of the most important diseases of horticultural crops. Pathogen attacks the roots and crown during entire growth stages, causing wilting or death of the plants. In this study, sampling from cucumber and tomato plants with symptoms of damping-off, root and crown rot was done from greenhouses located in Varamin and Pakdasht in 1394 and 1395 and after washing up and surface disinfection were cultivated on semi-selective medium of Phytophthora (CMA + PARPH). 16 isolates of the genera of Phytophthora drechsleri and P. nicotianae were isolated from crown, root and stem tissues of cucumber and tomato and pathogenicity confirmed on the host plants. In the second stage of the experiments, the efficacy of fungicide of Downy-G (Ridomil + Mancozeb WP 72%) in comparison with reference fungicides including Rosalaxil (Ridomil-Mancozeb WP 72%) and Previcur-Energy (Propamocarb Hydrochloride + Fosetyl Aluminium SL 840) in controlling cucumber damping-off based on a series of tests was investigated under greenhouse conditions (with two application method including soil incorporation system and soil drench system) and in the field conditions as soil drench system . Greenhouse trials with 6 treatments and 4 replications and field trials with 4 treatments and 4 replications were implemented at 2 locations in micro plots in Complete Randomized Design Block. The treatment evaluation carried out with determination of the percentage of infected plants in the period from emergence to 4-leaves stage. Greenhouse experiment results showed that Downy-G and Rosalaxil at 200 g/m3 of soil rates by 76.07% and 71.61% of decreasing disease in Soil Incorporation  application method, respectively, compared to infected control had the same effects in cucumber Damping-off disease control. In Soil Drench System application method, Previcur-Energy at 0.3% rates decreased disease by 99.64% compared to infected control and had the highest effects in disease control. In this application method, Downy-G and Rosalaxil at 0.2% rate decreased disease by 91.37% and 81.66% compared to infected control, respectively. The field trials results showed that Downy-G at 0.2% , Previcur-Energy at 0.3% and Rosalaxil at 0.2% rates decreased disease by 86.23% , 81.88% and 78.26%, respectively compared to infected control.

Bioassay of two native isolates of Bacillus thuringiensis (YD5 and 81) on Colorado potato leaf beetle Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae) as a serious pest of potato crop was performed. Variance analysis and mean comparison of the mortality percentage showed significant difference between standard isolates and native isolates in all the concentration. Although native isolates showed no acceptable results, there are some hopes to use them in higher concentrations.

Bean (Phaseolus vulgaris) is one of the most important legume family of plants and is an important source of protein in human nutrition that its yield reduces thorough competition with weeds every year. In order to evaluate the tolerance of P. vulgaris to metribuzin (Sencor) and haloxyfop-R-methyl ester (Super Gallant) were conducted as completely randomized design under controlled conditions in greenhouse of Colleague of Agriculture, Shahrood University of Technology in 2010. Treatments consisted of pre planting incorporation of Sencor in four replications and post application of Super Gallant in three replications of bean. Results showed that, about 5, 10 and 20 percent reduction in dry matter was evident respectively with application of metribuzin in doses of 496.9, 613.9 and 772.3 g.ha-1 and with application of haloxyfop-R-methyl ester in doses of 1033.8, 1686.6 and 2868.9 ml.ha-1. Based on this research results, Sencor can be used to treat broad leaves and narrow leaves weeds and Gallant super can be used to control narrow leaves weeds in bean fields respectively.

The purpose of this study was to provide a zoning map of susceptible areas to Fusarium head blight disease of wheat ear; the obtained model was compared by fuzzy logic method with the zonation map obtained from reports of Plant Protection Research stations in Golestan province. For this purpose, the average of humidity, temperature and precipitation parameters were determined for 45 days in autumn wheat growth period in the stage 65 of the Zadox scale. According to the opinion of plant pathologists and the time of occurrence of Fusarium head blight in Golestan province, preparation of zoning maps was determined through early-April to mid-May period in three days intervals. A total of 15 zoning maps were created and susceptible areas to disease were identified in this model. Zoning was classified into four categories: safe (0-25%), low risk (26-50%), hazard (51-75%) and high risk (76-100%).Validation of the results was admitted by Kappa coefficient method. The results showed that if the spikes were in the susceptible growth stage, the incidence and development of the disease would be predictable from early-April to early-May in the determined areas with a validation of 76%. The symptoms of the disease are not recognizable in the spikes during the mentioned period. The results of this study can be helpful for researcher and related experts in forecasting the disease and decision making of disease management at the best time.