نشریه دانش بیماری شناسی گیاهی
سال چهارم شماره 2 (پیاپی 8، بهار و تابستان 1394)

Soybean cyst nematode, Heterodera glycines, is widespread in major soybean producing countries and is considered as the most suppressed agent of soybean yield in the world. This nematode was reported from northern Iran in 1999 for the first time. Presently SCN is widely distributed in Golestan and Mazandaran provinces and infestation rate is a remarkable showing broad range of infestation. In most fields, the population density is above the damage threshold level reported for this nematode in the literatures. The HG Type 0 (race 3) has been defined as the dominant type in the region and Katoul (DPX) is the only resistant cultivar to this type of SCN in Iran. Importance of soybean cyst nematode, distribution and severity of infection, nematode morphology, symptoms, race/Hg Type, life cycle, reaction of Iranian cultivars against the dominant SCN Hg Type in Iran, and its management, based on the researches conducted in Iran and in the world are presented in this paper.

Bean, pea, lentil, vetch and broad bean grains are rich in protein. Kohgiluyeh and Boyer-Ahmad (a province in the southwest Iran) is one of the cultivation area of the pulses. In this province, five important fungal diseases included Fusarium wilt, Fusarium root rot, Ascochyta blight, Alternaria blight, and charcoal rot, are common on these plants. Symptoms of these diseases, key morphological characteristics of the pathogens and their distribution areas in Iran and the world is described.

Anthracnose disease is one of the most destructive diseases of strawberry which caused by Colletotrichum acutatum, C. gloeosporioides and C. fragariae. C. acutatum and C. gloeosporioides species complexes possess wider host range. According to the latest multi-gene phylogenetic evaluation, different strains of the causal agent of strawberry anthracnose disease which have been collected from different regions of the world, belong to these two species and are divided into several clusters, related to cryptic species. Despite infecting various parts of the plant, C. acutatum is mostly responsible for fruit rot and in comparison with two other species, causes crown rot and is more prevalent and destructive. Dispersal of pathogen inoculums mainly takes place by rain splash and sprinkler irrigation as well as by movement of human beings and animals. Integrated management of this disease is mainly achieved through cultural, chemical, biological and the use of resistant cultivars. Giving the importance of strawberry anthracnose disease in terms of damage rate and its recent incidence in many strawberry growing areas in Iran, different aspects of the disease, including diagnosis of the causal agent, biology and efficient management methods are discussed in the present review.

Accurate identification of fungi and fungus-like organisms is one of the most important steps for finding an approach to employ or control them. Nevertheless, this process is usually laborious and slow. Application of interactive keys is one of the ways to save the time and have an accurate identification of the species. An interactive key is a computer program in which the user enters morphological or molecular attributes of the specimen and the program compares them with the data of its database to find a match species with the highest similarity. Such keys also allocate separate images and other data for any known species. In this paper some of the interactive identification keys and their function is discussed.

The fungi Olpidium brassica and O. boronovanus, and two fungal-like species, Polymyxa beta and P. graminis, are known as important vectors of plant viruses. All of these microorganisms are obligate parasite of root and transmit the viruses belong to at least 12 genera and four families of plant viruses. In this paper, these vectors and their life cycle, transmitted viruses, methods of the acquiring and transmission of them are described.

With studying the function and co evolution of the plant resistance genes with virulence genes in the pathogens, the knowledge of molecular genetics is in progress and creates a new opportunity to produce durable resistance against plant diseases. This article explains the new findings about the different varieties of genetic resistance, performance and evolution of resistance genes involved in detecting, signaling and responding to plant pathogens.