Plant Protection
Year:2014 | Volume:36 | Issue:4|Papers Count:11

Saw toothed grain beetle, Oryzaephilus surinamensis (L.) is one of the most important stored-products pests. In order to find reduced-risk methods for controlling stored- products pests, the fumigant toxicity of essential oils from four plant species, Mint, Mentha longifolia (L.) (Lamiaceae), Sagebrush, Artemisia aucheri (Boiss) (Asteraceae), Rosemary, Rosmarinus officinalis (L.) (Lamiaceae) and Myrtle, Myrtus communis (L.) (Myrtaceae) was investigated on adult saw toothed grain beetles. The research was conducted under laboratory conditions (at 30±2oC and 60±5% R.H. 24 h darkness). Essential oils had a significant effect on mortality of adults, and mortality increased with increasing concentration and exposure time. The LC50 value of mint essential oil 0.35 m1/1 air calculated after 24 h exposure time was more toxic amongst the plant essential oils test. The LC50 value for rosemary, myrtle and sagebrush were 0.42, 0.50 and 0.99 m1/1 air, respectively. The LT50 value calculated at the highest concentration of 0.74 m1/1 air of mint essential oil was 16.4 h. Amongst the plant essential oils studied here mint had the highest potential insecticidal properties against this important economic pest.

Some samples of leaves and twinges of 'Mexican'lime, with bacterial canker symptoms were collected in spring and summer of 2012, from Dam province. Some bacterial isolates were isolated from infected tissues using classic methods. Primary identification of bacterial isolates was performed based on phenotypic characterization and spectral absorption properties of yellow pigment. Pathogenicity of isolates was approved on detached leaves and seedlings of Mexican lime and grapefruit in the greenhouse condition. The results of Phenotypic and genotypic identification, using four pair specific primers indicated that all isolates belong to Xanthomonas citri subsp. citri. The first identification results were approved using gyrB sequence analysis in candidate isolates. Comparing genetic fingerprint profiles with 3 type strains and other strains obtained from Kerman, Sistan and Balochestan, Hormozgan and Fars provinces showed that all Iranian isolates are similar in case of genetic fingerprint profile.

In recent years, application of municipal and industrial wastewater as irrigation water in agriculture has increased. Plant parasitic nematodes, especially root knot nematodes, cause damage to the most of agricultural products, and many efforts have been done to control them. To investigate the effects of wastewater on root knot nematode pathogenicity and damage on tomato, the inoculated plants by nematode were irrigated by different amounts of wastewater (0, 25, 50, 75, and 100%) in tap water as a completely randomized design with six replications. Analysis of variance and mean comparisons showed the positive effect of wastewater on increasing of growth indices and nutrient elements of plants. Thus, the length and fresh weight of plant shoots in 100% wastewater treatment increased: 62% (from 32 to 50 cm) and 30% (from 28 to 40 gr) compared to control, respectively. Nutrient elements such as nitrogen, phosphorus, calcium and magnesium also increased in wastewater treatments. However, the effects of wastewater were less on nematode pathogenicity.

In order to identify the plant parasitic nematodes associated with grape in Dena, Kohgiluyeh and Boyer Ahmad Province, Iran, about 50 soil and root samples were collected from different parts of the region during 2011-2012. The nematodes were extracted from soil samples using tray and centrifugal flotation techniques. The extracted nematodes were fixed and transferred to glycerin and the permanent slides were prepared. The fixed nematodes were examined by light microscope equipped with drawing tube and identified considering the morphologic and morphometric characters with the help of scientific keys and references. In this study, 8 species from 7 genera were identified as Aphelenchus avenae, Boleodorus thylactus, Helicotylenchus macronatus, Mesocriconema antipolitanum, M. xenoplax, Pratylenchus andinus, Psilenchus hilarulus and Seinura prospera of which P. andinus is a new report from Iran and B. thylactus, H. macronatus, M. antipolitanum, M. xenoplax and S. prospera are new reports from Kohgiluyeh and Boyer-Ahmad Province.

Fusarium wilt is one of the most important diseases of tomato plants. Because of the environmental hazards of chemical pesticides, it is necessary to use the non-chemical and natural methods to control the plant pests and pathogens. This study was performed to assess the possibility of replacing chemical fungicide with plant extracts. The antifungal effect of two plant extracts from Shirazi thyme, Zataria multiflora and Chavil, Ferulago angulata on the fungus Fusarium oxysporum f.sp. lycopersici was studied in the laboratory and greenhouse conditions. Concentrations of 0.4, 0.8 and 1.2 percent of aqueous extracts of the mentioned plants were added to PDA medium and water treatment without extract was used as control. The inhibitory effect of the aqueous extract of dried aerial parts of the plants on fungus grown on PDA medium was studied in vitro. Results showed that the extracts of both plants have an inhibitory effect on the growth of the fungus. Leaf extract of Z. multiflora at the concentration of 1.2% was more effective than that of F. angulata. In greenhouse experiments, the inhibitory effect of the plant extracts was evaluated in a completely randomized design with 12 treatments, based on the factorial Ishikawa pattern. In this experiment, leaf extract of Z. multiflora at the rates of 0.4, 0.8 and 1.2% and leaf and flower extracts of F. angulata each at the rate of 1.2% were best treatments.

Mungbean (Vigna radiate (Wilczek)) because of having high protein content, short geowing period and good tolerance to high temperature is one of the most important pulse crops in tropical and sub tropical regions. Mungbean is widely planted in Khuzetan province and the area under its cultivation in Khuzestan is significantly more than any other provinces in Iran. Fungal diseases of root and crown of this plant are among its important diseases worldwide. In this investigation, distribution and identification of the causal agents were studied. During summer and fall of 2010 and 2011, 78 samples were collected from Mollasani, Dezful, Shushtar, Abbid, Gotvand, Ramhormoz and Susangerd which are the main Mungbean cultivation areas in Khuzestan. Macrophomina phaseolina, Rhizoctonia solani and Fusariun solani were recovered from these samples. The collected data illustrated that M. phaseolina with the occurrence frequency of 70.51% was the main cause of the disease. R. solani with 17.95 and F. solani with 11.54% occurrence frequency belonged to a statistically separate group. Moreover, the reaction of the M. phaseolina isolates to potassium chlorate was studied. According to the results, the Macrophomina isolates were divided in two groups, chlorate sensitive to 77.3% and chlorate resistant to 22.7%. Among the chlorate sensitive isolates, two phenotypes - feathery and restricted growth- were identified while the phenotype of chlorate resistant isolates was dense growth. Statistically investigation into pathogenicity of different phenotypes of Macrophomina isolates showed that chlorate resistant isolates with dense growth intensively made infection and sensitive isolates with feathery phenotype ranked second, and sensitive isolates with restricted phenotype had the least pathogencity.

During a survey in the years 1384-1386 from olive orchards in Khuzestan province, a sample of olive trees showing symptoms viz wilting, dieback and in some cases decline was collected. After washing and surface sterilization, the suspected samples were cultured on PDA medium and incubated at 25 oC. In total, 124 fungal isolates from root and crown of olive were identified including a species from Verticillium (V. dahliae with 35 isolates), three species of Fusarium (F. solani with 23 isolates),) F. equiseti with 20 isolates), (F. semitectum with 4 isolates), three species of Cylindrocarpon (C. destructans with 20 isolates), (C. didymum with 8 isolates), (C. obtosisporum with 9 isolates), and R. solani with 5 isolates that were multinucleate and belonged to anastomosis group AG-4. The pathogenicity test of V. dahliae, F. solani, F. equiseti and C. destructans isolates were performed on olive seedlings 12 months by dipping the roots of seedlings in spore suspensions while R. solani isolates pathogenicity test was performed on a 12 -month-old olive trees and wheat. Results of pathogenicity tests showed that the isolates obtained from three species including F. solani, V. dahliae and C. destructans were as strongpathogens, F. equiseti as moderate pathogenic and R. solani as weak pathogen on olive. This is the first report of species F. equiseti and C. destructans on olive in Iran and species F. semitectum, C. didymum and C. obtosisporum as the olive pathogens.