Journal of Applied Research in Plant Protection
Year:2017 | Volume:6 | Issue:1 |Papers Count:9

Leaf spot disease is known as one of the limiting factors in cucumber cultivation in east Azarbaijan province and causes major damages on the crop yield annually. Purpose of the current study was to monitor leaf spot disease of cucumber in East Azerbaijan province and identify the pathogenic fungal species using morphological data. To this purpose, sampling was carried out during summer 2013 from main cucumber production areas of Shabestar, Ahar, Myianeh and Basmenj regians. During this research, a total of 90 samples were collected and 100 fungal isolates were isolated from infected samples that had various symptoms of leaf spot. Results of the present study confirmed that the leaf spot symptoms were caused by different fungal species in the provincial farms. By morphological study and investigation of macroscopic and microscopic features, the fungal species of Stemphylium mali, Ulocladium atrum, Cladosporium sp., Nigrospora oryzae, Bipolaris sorkiniana, Phoma sp., Pseudoprenospora cubensis, Bipolaris spicifera, Curvularia sp., Alternaria tenuissima were identified as the causal agent of cucumber leaf spot disease. Among the identified species, isolates of Alternaria tenuissima and Pseudoprenospora cubensis were more frequent than others with 48% and 13% isolation frequencies, respectively.

In order to evaluate the root-knot nematode infestation in pistachio (Pistacia vera L. ) orchards, soil and root samples of pistachio trees were collected from Rafsanjan orchards during different months of 2012-13. Based on morphological and morphometric characteristics of second larvae and adult females, M. incognita was found to be the dominant species (90% of total samples). The population dynamics of nematode larvae in the soil showed the least range 5 to 7 nematodes in June, September, December and March and the maximum, (50 to 210 nematodes per 100 grams of soil) in August. The highest density of nematodes per gram of root with 98 galls and 53 mature females were observed on August. The root-knot nematode populations were varied from 5 to 300 second juvenile per 100-gram soil. The eighteen plant species were found to be hosts for Meloidogyne incognita in pistachio orchards whereas M. javanica was observed on five species. The results of this study can determine the exact time of root-knot nematode control and the importance of weed management in pistachio orchards.

Watermelon mosaic virus (WMV) is a member of the genus Potyvirus in the family Potyiviridae. This virus is one of the most common and widespread viruses infecting cucurbits worldwide. In this research, partial biological and molecular characteristics of two WMV strains includingYAZ. WMV. 41 and YAZ. WMV. 55 collected from cucurbit growing farms in Yazd province were studied. These isolates did not react to polyclonal WMV antiserum in Direct and Indirect ELISA tests. Also, compared to several reported WMV isolates, these isolates induced different symptoms on the test plants. Coat protein (CP) gene (809 bp length) of these isolates was amplified in PCR, cloned and sequenced. Phylogenetic analysis showed that two Iranian and one previously reported WMV isolates (EU667626) are classified in subgroup IIB. Other Iranian isolates from the previous studies were clustered into sub groups I, IIA. Nucleotide sequence comparison indicated that these isolates share minimum and maximum nucleotide sequence identities (92. 2 and 99. 5 %) with a Spain (Accession no. AJ579518) and an Iranian (GQ421161) isolates, respectively. According to the results of this study, cucurbits are infected by different WMV isolates in Iran.

Members of Penicillium species contaminate agricultural products during both pre-harvest and post-harvest conditions, which result in crop yield reduction and quality. There is a huge paucity of knowledge on the prevalence of fungal species occurring on grape and raisin in Iran. The present study was aimed to characterize Penicillium species occurring on grapes and raisins in vineyards of East-and West Azarbaijan and Gazvin provinces. During 2011-2013 growing seasons, a total of 63 Penicillium isolates were recovered from berry and raisin samples of the surveyed provinces. The average of total contamination was 23% and the average of contamination in raisins and grapes samples were 1% and 33%, respectively. Determination of morphological properties of Penicillium isolates according to standard protocols were placed Penicillium species on grapes and raisins in studied areas in nine species of Penicillium and Talaromyces. The identity of species was confirmed using Beta-tubulun gene sequence data. The results of this study showed that Penicillium expansum with a frequency of 35% (22 isolates) was the most frequently occurring species Identification of Penicillium species associated with grape and raisin in vineyards of northwest regions of Iran will provide the possibility of adopting pollution control strategies.

Aphids are important pests on potato, whose principal damage relates to spreading of viruses. Status of aphid vectors, viral diseases and the relationship between them were studied in an experimental field, in which virus-free tubers were cultivated for two years. Yellow sticky traps were used for trapping the aphids and in the laboratory, cumulative population densities were determined for two groups of green peach aphid (as dominant species) and other aphid species. The relationship between population density of aphids (in two groups of green peach aphid and other aphids), infection percentage of different viruses (PVY, PVS, PVM and PLRV) and the relationship between them were evaluated using the slope of linear regression and correlation coefficient. There was a very significant relationship between population density of green peach aphid and other aphids. The relationship of different viruses, except PLRV, with a population density of green peach aphid and other aphids were also significant. The results showed that in spite of the great importance of green peach aphid in transmitting viruses to seed potato, in Freidan region the viruses could also be transmitted by other aphids. Significant relationship between PVY and aphids could account more spreading of this virus in the seed potato fields in this region.

Utilization of chemical pesticides has caused several problems such as raising serious concerns for human health and environmental hazards. Essential oils of aromatic plants have been proposed as safe and natural insecticides for control of insect pests. In this study, toxicity of essential oils of dill, celery and wild mint was tested against C. maculatus adults and E. kuehniella and P. interpunctella larvae. Based on chemical analysis by GC-Mass, (+)-carvone (48. 81%), apiol (22. 58%) and limonene (12. 61%) in dill. apiol (21. 82%), D-limonene (21. 21%) and 3-caren (11. 80%) in celery and myristicin (13. 35%), 3-terpinolenone (13. 33%) and 2-isopropylidene cyclohexanone (9. 23%) in wild mint essential oils were identified as main components. The essential oils indicated strong fumigant toxicity against all tested insect species. The LC50 values of wild mint, dill and celery essential oils against C. maculatus were 58. 958, 67. 769 and 94. 888 μ l/l, respectively. P. interpunctella larvae were more susceptible than E. kuehniella larvae and C. maculatus adults to dill essential oil. The essential oil of wild mint showed more fumigant toxicity than dill and celery essential oils against E. kuehniella larvae. P. interpunctella larvae were also more susceptible than C. maculatus adults to mint essential oil. According to the results of present study, essential oils of dill, celery and mint have good potential to be utilized as natural insecticides in management of C. maculatus, E. kuehniella and P. interpunctella.

Metarhizium anisopliae, is one of the most famous soil inhabitant entomopathogenic fungi, has a virulence potential on plant pests and animals. The green peach aphid, Myzus persicae, exists in all over of the Iran and causes damages to peach trees, citrus, vegetables and ornamental plants grown in greenhouses. The aim of this study is checking peach aphid mortality by Metarhizium anisopliae. Two strains of Metarhizium anisopliae, namely M1 and A3 available by Department of applied microbiology of Tehran organization of Academic Center for Education, Culture and Research (ACECR) were used in this study. Bioassay test against peach tree aphids was done in 18 cm diameter Petri dishes with three gradient suspensions consisted of 1×103, 1 ×105 and 1 ×107 conidia ml− 1 and 14: 10 h of dark: light photoperiod in ambient temperature for 9 days. The least amount of LC50 determined for A3 with concentration of 6. 5×105 conidia/ml and the best LT50 for A3 with concentration of 1×107 conidia ml− 1 was 3. 82 days. The least LT50 for M1 with concentration of 1×107 conidia ml− 1 was 5. 51 days.

Colorado potato beetle is one of the most important insect pests of potato plants. Frequently and prolonged use of chemical pesticides for controlling this pest, has caused environmental pollution, pest resistance to pesticides and destruction of natural enemies. Some herbal extracts are more degradable and relatively safer than most of the synthetic insecticides and can be used as suitable alternatives in integrated management of Colorado potato beetle. In this study, the effects of leaf extracts of Juglans regia, Sambucus ebulus, Artemisia annua, Satureja sahendica and Salvia sahendica were studied on 2nd instar larvae of Colorado potato beetle, Leptinotarsa decemlineata in laboratory conditions at 26 ± 2 ° C, 55± 5% RH and a photoperiod of 16: 8 (L: D). Potato leaves were treated with 0. 625, 1. 25, 2. 5, 5 and 10% concentrations of the plant extracts using leaf-dipping method. Control leaves were dipped in either methanol or distilled water only. Each treatment consisted of 20 up to 24 h old 2nd instar larvae and had three replicates. Mortality of the larvae was recorded 24, 48, 72 and 96 hours after treatment. The results showed that extracts of Juglans regia, Satureja sahendica and Artemisia annua were more toxic to 2nd instar larvae of the Colorado beetle than Salvia sahendica and Sambucus ebulus. Ninety six hours after treatment, 10% concentration of J. regia, S. sahendica and A. annua caused 93. 33, 91. 67 and 73. 33% mortality and 5% concentration of these extracts caused 58. 9, 100 and 48. 2% mortality in Colorado potato beetle larvae, respectively. As expected, the mortality decreased with decreasing concentrations. According to the high mortality percent, especially in high concentrations, the extracts of these plants, can be used as potential botanicals for integrated management of Colorado potato beetle.

East Azerbaijan province is one of the major producers of almond and its improved varieties of this priceless species in Iran. Almond trees are attacked by different kinds of pests, such as aphids, during their lifetime. The aphid Hyalopterus amygdali (Blanchard, 1840) is the predominant pest on almond trees in East Azerbaijan province. This pest severely weakens their hosts by eating the phloem sap of leaves and shoots of almond. In this study, antibiosis of five almond cultivars; including Sahand, Shekoofe, Azar, Ferragnes and Ne Plus Ultra; was studied against mealy almond aphid (H. amygdale) in field condition. The estimated variables were the survival rate of nymphal stage, its developmental time, growth index, fecundity and intrinsic rate of population increase (rm) of adult apterous mealy almond aphid. The ANOVA of the data indicated that regarding duration of nymphal developmental time and adult fecundity, there were no significant differences between the cultivars. But, the mean of relevant intrinsic rate of natural increase (rm value) of apterous adult was significantly different between the cultivars (P < 0. 05). According to results, mean survival percentage of nymphal stage, developmental time, number of offspring and rm values were 68 ± 3. 86 %, 8. 96 ± 0. 11 days, 38. 02 ± 2. 21 nymphs and 0. 2581 ± 0. 0043 f/f/day, respectively. The orthogonal comparison of Sahand as a local cultivar with hybrid and foreign cultivars showed that there is a significant difference between them in all traits (p<0. 01). In this regard, grown aphid on Sahand showed lower fecundity and lower intrinsic rate of population increase. As conclusion, Sahand can be considered as a relatively resistant cultivar to mealy almond aphid compared to other cultivars.