Plant Pathology Science

Introduction: Early blight caused by Alternaria species is one of the most important tomato diseases in the world. The disease has been reported from most areas in Iran with up to 90% infection. This study was conducted to investigate the effect of nano-chitosan on the severity of the ‎disease and its use as a replacement‎ of the chemical fungicide, chlorothalonil. Materials and Methods: Diseased tomato plants of fields and greenhouses of Fars province in southern Iran were sampled. Pathogens were isolated from diseased tissues, purified and identified by studying their morphological characteristics. The effect of nano-chitosan at three concentrations of three, five and seven grams per liter and the fungicide chlorothalonil were tested before and after inoculation of two pathogens. The disease severity indexes were measures in Sunseed and 16 cultivars of tomato under greenhouse conditions using a factorial experimental in completely randomized design with four replications. The data were analyzed with comparing the means. Results: The isolated pathogens were identified as A. solani and A. alternata. Results of the greenhouse experiment showed that A. solani was more aggressive than A. alternata and the cultivar 16 was more resistant to the disease. Nano-chitosan at 5 and 7 mg/ l significantly reduced disease severity indexes when use before pathogen inoculation, and at 7 mg/l when use after pathogen inoculation. Conclusion: Nano-chitosan can be used as a bio-fungicide to replace chlorothalonil as a chemical fungicide for disease management.

Oak charcoal rot is caused by two fungi, Biscogniauxia mediterranea and Obolarina persica. These fungi, which are opportunistic or secondary invaders and attack stressful trees, are one of the main problems of oak forests in Iran. The disease was first reported in 2011 in the northern forests on Quercus castaneifolia and Zelkova carpinifolia trees and then in the Zagros forests on Q. brantii tree. The disease has spread rapidly in the forests of the Zagros over the years. Symptoms of the disease include decay and death of trees, browning of leaves and early fall. Gum secretion on the branches and trunks of old trees and browning of wood texture and woody vessels can be seen up and down the height of the trunk. The morphological characteristics of pathogens, the spread and survival of pathogens, and disease management methods are described in this article.

Introduction: Ganoderma lucidum, medicinal mushroom, is one of the most effective traditional medicine in East Asia. The mycelium, the spore and the basidiocarp contain about 400 different bioactive compounds with polysaccharides, peptidoglycans and triterpenes as active ingredient groups of medical value. Underwater cultivation is one of the most reliable technologies to produce the industrial biomass of this mushroom, which contains anti-tumor and anti-cancer polysaccharides. Regarding the growth of fungal mycelium, it is related to various environmental factors such as pH, temperature and available nutrients. The aim of this study was to determine the influence of pH, temperature and different concentrations of the carbon and nitrogen sources on the growth rate of fungal biomass in sugar cane molasses. Materials and Methods: The first part of the study dealt with the morpHological and molecular identification of an Iranian isolate from G. lucidum.  Then the effects of carbon sources of arabinose, maltose, cellulose and xylose at concentrations of 0.1, 0.2 and 0.3%, and nitrogen sources of yeast extract, MgSo₄.7H2O, peptone and K₂Hpo₄ at concentrations of 0.2, 0.3 and 0.4%, pH 4, 4.5, 5 and 5.5, and a temperature of 25° C, 28° C, 32 ° C and the number of 2, 3, and 4 inoculum particles of 5 mm² for the production of mycelium biomass of G. lucidum, in sugarcane molasses was studied, in completely randomized design experiments with four replicates for each treatment in vitro. Results: A comparison of the mean dry weight mycelium of G. lucidum produced with different treatments showed the significant differences between the treatments with a probability of 5%. The highest yield of G. lucidum was obtained in peptone with concentration of 0.3%, maltose with concentration of 0.2%, pH=5, 3 inoculum particles with 5mm² diameter, at 28°C. Conclusion: Sugar cane molasses can be used as a cheap and inexpensive medium for the biomass production of G. lucidum. For the first time this study showed that by adding peptone with concentration of 0.3%, maltose with concentration of 0.2%, to sugarcane molasses, with 3 particles of inoculum with 5mm² diameter, in pH=5, and 28°C, the highest biomass of this medicinal mushroom could be produced.