Bacterial speck of tomato, cused by Pseudomonas syringae pv. tomato, was reported from Varamin in 1994. Subsequent surveys of tomato fields in Varamin during the spring and summer months in 1995-96 revealed variabilitis in symptoms type and severity of infection among plants within and between farms. Disease symptoms appeared as regular or irregular brown to black lesions on LEAF, sepal, peduncle, branches and stems. Specks, with or without chlorotic haloes, appeared on fruits. Fifty three strains were isolated from affected tomato plants and their phenotypic features and electrophoretic patterns of cell proteins were compared. Two pathovars of Pseudomonas syringae were found to be involved. One group was identified as P. syringae pv. tomato (Pst) (causing bacterial speck of tomato). Their phenotypic features were very similar too but different from the type strain with respect to hydrolysis of esculine, tolerance to 5% NaCI, tyrosinase activity, utilization of lactate, L-histidine and adenine and production of mucoid growth on yeast dextrose calcium carbonate agar (YDC). Their electrophoretic profiles of cell proteins were similar but the strains could be differentiated into two groups, based on the relative mobility and intensity of a few protein bands. The second group of strains were indentified as syringom deficient strains of P. syringae pv. syringae (Pss) causing syringae LEAF SPOT. The electrophoretic profiles of cell proteins of the two Pss strains were identical and very similar to that of a Pss strain isolated from peach (prunus persica)

Progress of Cercospora LEAF SPOT (CLS) caused by Cercospora beticola was studied in the field, at Safi-Abad Research Station during two successive growing seasons (2000-2002), using completely randomized block design experiments with 4 replicates. In the first year one variety, Monondera, and 4 sugar beet lines: 7112, 261, 191 and 236, were used. In the second year var. Monondera was replaced with Var. HM-1836. Plants were artificially inoculated using spore suspension. Disease progress was recorded according to a numerical scale of 0 to 5 as soon as the first disease symptoms appeared on the outermost leaves. Data were analyzed and fitness of epidemiological models monomolecular, logistic, log-logistic, Gompertz and Weibull were evaluated. The results indicated that, in the first year the logistic and log-Iogestic models showed the best fitness with the actual disease progress observed whereas in the second year logistic, log logistic and Gompertz were more efficient models in determining disease progress. Combined analysis of the results for the two years of this study showed that the logistic model was the most efficient in defining disease progress, whereas the monomolecular and Weibul modle were inefficient. This study revealed that cercospora LEAF SPOT appears in early March and the disease progressively increases until early June. To reduce the damage caused by the disease it is recommended to give priority to harvesting date of infected fields.

In order to investigate the bacterial agents causing kiwifruit LEAF SPOT disease in Iran, sampling performed in two consecutive years from the kiwifruit growing areas in the northern provinces. More than 400 bacterial strains isolated from the leaves of infected trees with various signs of LEAF SPOT like brown angular SPOT, white SPOT with brown border, orange color SPOT and water soaking SPOT with yellow penumbra. 130 strains identified as pathogenic factors in different pathogenicity test. Among them, 25 strains were suspicious to have the Pseudomonas genus according to morphological properties such as color and shape of the colonis and studed from the phenotypic and molecular view point. All the strains had positive result through the hypersensitive reaction test in tobacco and geranium leaves, but during other phenotypic and molecular tests, they had different results. These tests proved that half of the strains in this study have the most similarity to P. syringae. Using two pairs of specific primers that designed based on the 16S-23S rRNA (ITS) sequence, by the name of PsaF1⁄R2 and PsaF3⁄R4, made it clear that strains: 20, 86, 101, 138, 132, 117, 194 and 230, are belonging to P. syringae pv. actinidiae. This experience that rpoD gene sequence of other 17 strains and its dissimilarity to any of the rpoD gene sequences, belonged to the species of genus Pseudomonas in the genebank, proves that these strains are unknown species of Pseudomonas, makes it necessary that determind the taxonomic status of these strains further investigations are required.

Several LEAF SPOTting or blotching fungal diseases occur on forest trees in Guilan province (N Iran). Some of them such as maple tar SPOT affect health of host trees severely, but many are of minor effect. This study was carried out to identify unknown and less known fungi causing LEAF SPOT and LEAF blotch diseases on broad LEAF trees in this region. So far numerous fungi were collected. Four species viz. Sphaeropsis mespili (on Mespilus germanica), Seiridium unicorne (on Crataegus melanocarpa), Septoria cornina (on Cornus sanguinea) and Tubakia dryina(on Quercus castaneaefolia) and two unidentified species belonging toCylindrogloeum sp. (on Fraxinus excelsior) and Monostichella sp. (on Corylus avellana) are recorded for the first time from Iran. Furthermore, Phloeospora aceris(on Acer cappadocicum) and Marssonina juglandis(on Pterocarya fraxinifolia) are new members to Guilan mycobiota.

Thirteen sugar beet cultivars exhibiting increasing levels of resistance to Cercospora LEAF SPOT were used in order to study the following resistance components to the disease w1der controlled conditions in greenhouse: incubation period, percent of infected leaves, the number of necrotic SPOTs per cm2, lesion diameter and number of conidia produced on necrotic SPOTs. Incubation length was determined by two different methods. In both of them degree – days was used instead of time to record the incubation period. In the first method degree-days cumulation during the time between inoculation and appearance of SPOTs in fifty percent of plants, was considered as incubation time and in another method the appearance of fifty percent of SPOTs was used to determine the incubation time. All the resistance components were involved in host resistm1cesignificantly. With few exceptions, by increasing in level of resistance, the number of SPOTs per cm2, lesion diameter, percent of infected leaves and spore yield were decreased and incubation length was increased.    

In order to study of cabbage LEAF SPOT disease in Damavand region, Tehran province, Iran, symptomatic cabbage leaves (Brassica oleracea var. capitata) were collected during the late summer and fall of 2017. Twenty-one isolates with the main characteristics of the genus Alternaria were isolated from lesions on the cabbage leaves. Based on morphological characteristics and phylogenetic analysis using multi-gene sequences, they were identified as Alternaria telliensis. Pathogenicity tests were conducted on cabbage leaves under greenhouse conditions and characteristic lesions were formed on inoculated leaves. Re-isolation of the inoculated fungus from the treated leaves confirmed Koch’s postulates. Based on the available information, this is the first occurrence of A. telliensis as a new species and pathogen to cabbage plants in Iran.

A diallel cross analysis was used to estimate general and specific combining ability of resistance to cercospora LEAF SPOT in six lines of sugar beet. The parents and 15 hybrids (F1) were evaluated in a randomized complete block design with four replications at Safiabad Agricultural Research Center. A mixture of cercospora agent was grown in the laboratory in V8A media. The infection was created in "Khusestan", in 2001 by three times sprays. Genetic parameters were estimated by Griffing, Jinks and Hyman methods. The results showed that both additive and non-additive genetic effects contributed to the expression of this trait, but the portion of additive and heritable effects of genes are more important. Therefore, there is a relative dominance in genetic control of LEAF SPOT infection. Broad sense and narrow sense heritability were 99% and 79%, respectively. Because of a high amount of additive gene effects and rather high narrow sense heritability, the selection efficiency would be successful in cercocpora LEAF SPOT resistance. The results also indicated that the resistance to this infection could be controlled by recessive genes. Parents 7617 and 261 with less infection intensities have general combining abilities in resistance, so they are suitable parents for resistance increase and can be used in breeding program.