Biocontrol of Phytophthora cactorum the causal agent of root and crown rot on apple (Malus domestica) by formulated Pseudomonas fluorescens.

In this study 284 isolates were isolated of apple trees' rhizosphere from Iran and 128 isolates were obtained from the collection of Research Department of Biological Control of University of Tehran. Four strains (P60, P61, P96, and P97) of Pseudomonas fluorescens were selected for greenhouse trials. The results of greenhouse trials showed dipping the crown and root of apple seedlings (MM106) combined with soil drench was more effective than dipping the crown and root on reducing the disease. After 6 weeks, strain P60 in dipping method combined with soil drench with 70% control, exhibited greatest effect on reducing the crown and root rot and was more effective than the fungicide metalaxyl-mancozeb. After 12 weeks, strains P60 and P96 in dipping method combined with soil drench with 55.6% and 44.5% control respectively, exhibited greatest effects on reducing the diseases Study of media on growth rate populations of effective strains exhibited that the beet molasses yeast extract (1:1) had more effect than nutrient broth(NB) medium. The initial high populations of powder formulations of strains P60 and P96 decreased during the storage at 4 and 25 degrees C over a 150-day period. In addition, formulations of strains stored at 4 degrees C had longer shelf life than those stored at 25 degrees C. In glasshouse trials, after 6 weeks, formulation of strain P60 and unformulated P60, obtained from NB medium and formulated P60, obtained from molasses yeast extract medium, and metalaxyl-mancozeb had highest effect on reducing the disease on apple rootstocks. After 12 weeks, formulation of strain P60 and unformulated bacteria obtained from both media, and metalaxyl-mancozeb with 57.1% control showed greatest effect on reducing the disease.

Study on infection symptoms of root-knot nematode, Meloidogyneja vanica, on the stem of the tomato seedlings in greenhouse.

On the first of seeds germination, Meloidogyne javanica induced knots on the stem eventually by to penetrate into the coleoptiles. In this experiment, used soil was loamy-sandy type, pH=7.2, including 1.5% composts. Tomato seedlings of cultivar Rutgers were used as host. This experiment was conducted in Completely Randomized Design with 3 treatments and 10 replicates as fallow: (1) control, (2) 10 J2s/cm3 of soil, (3) 20 J2s/cm3 of soil. In each pot (1000 cm3), 50 seeds were planted. Inoculation was done, a day after to plant seeds, in 2 cm depth. Pre-emergence and post-emergence damping-off, number of stem-knots, height of knots on the stem in 3 treatments was more than 2 treatments. In some of the pots of 2 treatments were not observed stem-knots. As long as four weeks after planting, there was not significant difference in fresh weight and height of the seedlings in treatments. Numbers of adult females in 3 treatments were more than 2. In the stem-knots, collenchymas tissue, endodermis and stem cambium were found deformed J2s and J3s, and adult females.

Occurrence and distribution of lettuce mosaic disease in Tehran province from Iran.

Lettuce mosaic virus (LMV) Cucumber mosaic virus (CMV) and Tomato spotted wilt virus (TSWV) were identified in fields of Tehran province. In this study 452 leaf samples were collected from the fields throughout the Tehran province during 2002 and 2003. Distribution of Lettuce mosaic virus (LMV), Cucumber mosaic virus (CMV), Tomato spotted wilt virus (TSWV)and Arabis mosaic virus (ArMV) was determined with DAS-ELISA. Percentage of single Infection to LMV. CMV or TSWV was 20.58, 15.93 and 9.96% respectively. Also 15.28% of samples were co- infected with LMV+CMV, 8.19% with LMV+TSMV and 7.74% with CMV+TSWV. 4.65% of samples were Infected to all of these three viruses. LMV was found in 48.69%, CMV in 43.59% and TSWV in 30.54% of samples totally. Therefore LMV is major dominant agent of lettuce mosaic disease in Tehran province. This is the first report of occurrence of TSWV on lettuce in Iran and first report of CMV and LMV in Tehran province.

Biological and molecular characterization of lettuce mosaic virus from Tehran province in Iran.

In this study, lettuce samples having LMV infection symptoms were collected from Tehran fields during 2003. Samples tested for LMV infection by immuno printing. Three positive samples in immuno printing collected and their characteristics were determined. In mechanical inoculation, these Isolates produced symptoms on Chenopodium quinoa, C. amaranticolor, Gomphrena globosa, Nicotiana benthamiana, Lactuca sativa cv. Mantilia and cv. Terocadero (which contains the mol1 resistance gene and susceptible respectively), but not cv. Salinas 88 (which contains the mol2 resistance gene). LMV was purified and LMV polyclonal antiserum was produced in rabbit by a series of intravenous and intramuscular injections, the precipitin titre of this antiserum was 1:1024. Gel double diffusion test (GDDT) was performed, and precipitin bands appeared. SDS-PAGE and western blotting showed the presence of coat protein 29 kDa. In IC-RT-PCR with on LMV specific primer pair, an approximately 1300 bp fragment was amplified.

Barley leaf stripe disease.

Leaf stripe is one of the most important diseases of barley in Iran especially in Gorgan, Mazandran and near Tehran (Varamin). Most obvious symptoms of the disease are described. Long pale or yellow stripes become darker as the fungus sporulates on the leaf surface. Infected plants usually are stunted and produce sterile spikes, rarely a few seeds are produced. Infected spikes and late-forming tillers may produce fertile spikes. The fungus is seed brone and survives in the outer layers of infected seed. To study the seed-borne disease, we have used the different methods (ISTA). Coleoptiles of seedlings are infected by the fungus under cool, moist conditions, a soil temperature below 15 degrees C is necessary for seed infection. The fungus penetrates through coleoptiles and grows systemically within the plant, produces toxin and kills cells and discolors leaf tissue between veins, thus causing striped lesions. When conditions are wet or humid, spores are produced on the surface of leaves at above the time spikes of healthy plant. Morphological characteristics of the vegetative and reproductive structures of the fungus show that it is Drechslera graminea (Rabenh) Shoemaker.