Plant Pathology Science

Wheat is one of the most important cereals grown as human and animal food in the world, including Iran. This crop is infected by various pathogens such as fungi. Graminicolous fungi are important pathogens which cause root and crown rot, leaf blight and black spot on wheat. Some methods, with high efficiency and safety for human and environment, have been employed for controlling these diseases. Since the activity of these fungi depends on some factors such as soil temperature, pH, moisture and nutrients, the proper agricultural practices before planting and suitable irrigation and good fertilization would be effective in pathogen control. Various species of Trichoderma, arbuscular endomycorrhizal fungi and some bacterial species may control the disease through some mechanisms such as biofilm production, plant growth promotion and enzyme production. Generally, integrated management with the aid of simultaneous application of several control measures would give the best results.

Introduction: Cereal cyst nematodes (CCN), Heterodera species, are important parasitic nematodes of cereal. Potato cyst nematodes (PCN), Globodera species, are also serious pests of potato world-wide. Continuous monitoring of these nematodes is necessary to prevent their damage to their host plants. This study was conducted to determine the distribution and density of these nematodes in Ardabil province, northwest of Iran, where potatoes are planted in rotation with cereals. Materials and Methods: One hundred and two soil samples were collected from potato fields in the suburbs of Ardebil, Nair and Namin cities in the first year, and 116 soil samples were collected from the wheat fields that were cultivated in the rotation with potato in the second year. The samples were transferred to the laboratory and examined for cyst nematodes. After isolating the cysts, identification of the species was performed based on morphological and morphometrical characteristics of the cysts and the second stage larvae. Results: Examination of the collected samples in both of two years indicated the presence of CCN in some soil samples, but PCN were not observed in none of the soil samples. The morphological and morphometrical data of isolated cereal cysts and comparison with valid identification keys led to the identification of Heterodera filipjevi. Mean numbers of the cysts with eggs and larvae in those samples that were collected in the first and second year were respectively 0.76 and 0.11 in 100 g of the soil. Wheat fields of Ardebil had the highest and fields of Nair had the least number of cyst nematode.  Conclusions: The results of this study showed that some of the wheat fields in the province were infected with H. filipjevi and potato fields were not infected with any cyst nematode.

Glume blotch caused by the fungus Parastagonospora nodorum is an important disease of bread and durum wheat. The disease reduces the quantity and quality of wheat product. Disease history, pathogen morphology, and disease management methods, including crop rotation, plowing, post-harvest collection of plant debris , weed control, healthy seed culture or seed disinfection with a systemic fungicide, and cultivation of resistant cultivars are described.

Introduction: Poaceous plants such as corn, wheat, barley, sorghum, oats and millet are an important part of agricultural ecosystems. Smuts are one of the most important fungal diseases of these plants, which often cause economic damage and the destruction of part or all of their yields. Materials and Methods: Poaceous smut infected plants in farms and pastures of Markazi and Lorestan provinces were sampled. Morphological characteristics of these fungi and their germination type of teliospores were studied with bright field and fluorescent microscopes and identified using valid keys. The phylogenetic relationship of these fungi with other smuts was also investigated based on ITS-rDNA region sequencing. Results: According to the type of host, morphological characteristics and mode of teliospores germination 12 species vs. U. maydis, U. hordei, U. turcomanica, U. avenae, U.nuda, U. bromivora, U. cynodontis, U. tritici, Tilletia laevis, Tilletia controversa Sporisorium reilianum and S. cruentum were diagnosed. The morphological characteristics and phylogenetic relationship of these fungi with other smuts are described. Conclusion: The smuts of poaceous plants in Markazi and Lorestan provinces include eight species of the genus Ustilago, two species of the genus Sporisorium and two species of the genus Tilletia.