Synthesis and characterization of chitosan nanoparticles and their effect on Fusarium head blight and oxidative activity in wheat.

The main aim of present study was to prepare chitosan (CS) and chitosan nanoparticles (CS/NPs) to evaluate their antifungal and oxidative activity. CS/NPs were prepared based on the ionic gelation of CS with tripolyphosphate (TPP) anions by using centrifugation and pH change. The obtained nanoparticles (NPs) were characterized by size and zeta potential analysis. The antifungal activity of the CS and CS/NPs were evaluated on the Fusarium graminearum, which causes Fusarium head blight (FHB) on wheat by the method of spraying on the Potato dextrose agar (PDA) medium. The Dynamic light scattering (DLS) indicated that particle diameter (z-average) was approximately 180.9±35.5-339.4±50.9 and 225.7±42.81-595.7±81.7nm for NPs prepared from CS with different molecular weights by using centrifugation and pH change methods, respectively. Different concentrations of CS and NPs were tested to know the inhibitory effect of F. graminearum. Low molecular weight (LMW) CS and its NPs had high potential of antifungal activity on suppress of fungus growth. The maximum percentage of growth reduction was 68.18%, and 77.5% by CS and its NPs at concentrations of 1000 and 5000ppm, respectively. In greenhouse trials, at 28days after inoculation (dpi), the area under the disease progress curve (AUDPC) from 7 dpi to 28 dpi of control plants treated with acetic acid aqueous solution and distilled water was almost up to 7.36 and 7.7, respectively, while plants treated with CS and NPs only had approximately 3.61 and 3.34, respectively. Results revealed that H2O2 accumulations displayed a different pattern during the activation of plant defense systems, it had brownish sites on the infected palea. Since 24h post inoculation (hpi), the H2O2 accumulations were shown in both CS and NPs, and the elevated H2O2 accumulation appeared in 72 hpi in both treatments. CS and NPs at high concentration increased the degree of tissue and cell injury. The obtained results clearly suggest that CS and its NPs have remarkable potential for further field screening towards crop protection.

Application of chitosan and chitosan nanoparticles for the control of Fusarium head blight of wheat (Fusarium graminearum) in vitro and greenhouse.

Fusarium head blight (FHB) disease caused by Fusarium graminearum is one of the most important diseases of wheat in humid and warm areas. This disease significantly reduces yield as well as seed quality. The aim of this work was to evaluate the possibility of control of FHB by chitosan (CS) and chitosan nanoparticles (CS/NPs). In vitro, the application of various concentrations of CS and CS/NPs showed significant inhibition of both radial mycelial growth and number of colonies formed against F. graminearum. The application of 1000 and 5000ppm concentration of CS and CS/NPs produced maximum inhibition of radial mycelial growth in comparison to the control, respectively. The microscopic examination, of treated F. graminearum with the CS and CS/NPs, showed dehydration and deformation in mycelial growth and some hyphae were collapsed. The maximum percentage reduction number of colonies was observed in 5000ppm concentration of both CS and CS/NPs. To test the effect of CS and CS/NPs on spore germination, four concentrations were used for 4 and 24h incubation. The 24h incubation of F. graminearum spores with a 5000ppm solution of CS greatly reduced the number of germinating spores. In greenhouse trials, the disease severity percentage was low when CS and CS/NPs were applied before fungus inoculation on the plants and 1000ppm concentration. The spores of F. graminearum germinated on the anther, hyphae penetrated into anther and colonized the palea, lemma and glume after 24 and 72 hpi, respectively. Wherease, the spikelets treated with CS and CS/NPs were infected slowly. Light microscopy and TEM observations indicated that mycelium penetrated into the cells through stoma and transited to other cells by cell wall or plasmodesmata. Mycelial growth caused conidia into cells but CS and CS/NPs prevented of it's growth. Results showed that CS and CS/NPs could be a useful biological pesticide for controlling FHB.

Pistachio gummosis disease caused by Phytophthora species and its control management with soil solarisation method in Iran.

Pistachio (Pistacia vera L.) is the most important commercial product in Iran and root rot or crown rot (Gummosis) is the most serious diseases of this crop. During 2005-2007 Infected trees of Pistachio orchards were visited and plant samples plus soils around the infected trees collected from Kerman province in Iran. Samples were transferred to laboratory and cultured on common medium and using citrus leaves pieces as baits on water-saturated soils. Different Phytophthora species were isolated and studied to be identified. Three Phytophthora species including P. megasperma, P. drechsleri and P. citrophthora were the principal cause of pistachio gummosis and root rot in Iran. However, Phytophthora pistaciae as new species was introduced as aggressive species to different Pistachio cultivars. Since chemical control was not property managed the disease, soil disinfestations by soil solarisation method was carried in Kenrman as the nearly warmer climate in studied areas to manage the pathogen. Application of this method reduced population density of the pathogen from 1300 to 200 CFU -g/soil after 6 weeks. This method was effective, non negative side and economic which can be used in all agricultural areas.

Major Fusarium diseases on crops and their control management with soil solarisation in northwest Iran.

Fusarium species are the most frequently soil-borne fungal pathogens on crops that make high economical damages in Iran. Studies showed that Fusarium species cause significant yield losses in main crops especially potato, pea, bean, wheat, corn and rice in northwest Iran. The diseases resulted in yield losses to the extent of 30% to 70% in the fields and made economical problems for growers. Infected plants were collected and cultured common medium (PDA) and selective media (PPA, CLA) for Fusarium species after surface sterilization. The dominant species were F. solani, F. oxysporum, F. graminearum, F. moniliforme, F. sambucinum, F. culmorum, and F. equiseti in area studied. Soil solarisation method was carried at the summer season in three soil infested locations to assess the control management of the pathogens. Application of this method reduced population density of the pathogen from 1900 CFU -g/soil to 500 after 4 week. This proper method was simple, effective, non negative side and economic which can be used in nearly different farming areas at warm season.

Biological control of Orobanche aegyptiaca by Fusarium oxysporum F. sp. Orobanchein northwest Iran.

Broomrape (Orobanche aegyptiaca) is one of the most serious weed pathogen on many plants all over the world, especially in northwest Iran. It causes damage on some plants particularly on tomato, cucumber and other dicotyledonous crops in zanjan province. Broomrape as weed, caused reductions in crop yield, adversely affected crop quality, and resulted in loss of cultivated land due to reduced crop alternatives. Since there were no any chemical methods and other proper technique to control this plant parasite we tried to find a good mechanism for its management in the fields. Our study showed there was a specific species, Fusarium oxysporum f. sp. orobonche that had infected Broomrapes naturally in the field. In point of fact the species was isolated from naturally infected Broomrape in studied Locations. Our surveys showed F. oxysporum f. sp. orobanche caused disease on orobanche spp. in different agricultural fields. Although there were other fungal species which can nearly manage the orobanche but it can be fungal pathogen to other plants. However the best fungal isolate can be F. oxysporum f. sp. orobanche since it may not be pathogen for other plants.

Incidence of crown rot disease of wheat caused by Fusarium pseudograminearum as a new soil born fungal species in north west Iran.

Root rot and crown rot is one of the main important fungal diseases on wheat in North West Iran. The disease was studied during 1999-2004 growing seasons in four provinces including Qazvin, Zanjan, East Azarbyjan and Ardabil. Different wheat fields in the areas studied were visited and samples of the plants showing symptoms like chlorosis, withering, whiting of spikes, growth reduction and white heads were collected and transferred to the laboratory. Samples were surface sterilized with sodium hypochlorite and then cultured on common media (PDA) and specific media (PPA and CLA). Totally 155 fungal isolates belonging to five genera were identified and the pathogen most frequently isolated was Fusarium pseudograminearum (formerly known as F. graminearum Group 1). This species normally causes crown rot resulting in severe damage in several locations under dry spring conditions. The disease caused losses from 18-45.5% in the fields where the season and crop rotation allowed the disease to build up. Prolonged moisture stresses coupled with relatively high soil temperature in the fall enhanced early disease development on the roots and sub crown internodes. Environmental conditions and genetic susceptibility of cultivars were the two main factors affecting diseases incidence.

Naz, a resistant cultivar on bean root rot disease in Zanjan province, northwest Iran.

Field bean is a major crops in different parts of northwest Iran especially Zanjan province. Recently the bean plants were severely subjected to damping off or decline disease which caused yield losses in bean growing regions. A regional research was done from 2003 to 2005 to get general information on the causal agent of disease and its control management. Infected plants were collected from different studied areas and transferred to laboratory. Crown and plant roots were cultured in PDA as common media and PPA as selective media for Fusarium species after surface sterilization with sodium hypochlorite. Plates were incubated in standard culture room then isolated fungi were identified. Different Fusarium species were isolated, however the main pathogen isolated from plant samples and soil around the roots was F. sambucium Fuckel. The disease caused up to 50% yield losses in some fields in studied areas. Study showed the "Naz" cultivar was the main resistant race to the disease and had the most yield production in the field.

Introduction a potato cultivar "sprit" as relatively resistant to main fungal pathogens causal agents of early blight and wilting on potato in Iran.

Potato (Solanum tubersum L.) is one of the most human food production cultured in Iran especially Zanjan province as a temperate region. Some fungal pathogens caused severely infected on potato tubers or foliage in the majority grown areas and resulted yield losses in potato production. Recent years from 2002 to 2004 infected samples were collected from different potato grown regions in Zanjan province then cultured on PDA after surface sterilization with sodium hypochlorite. Isolated fungal pathogens were identified and study showed the main pathogens with high incidence and frequency were Alternaria solani, Fusarium oxysporum and Verticillium sp. in studied areas. The regions which used convention varieties showed more diseases than other locations which used relatively resistant races. The rate of resistance for 10 international potato varieties was studied by inoculation of them by 10(5) spores suspension of three common fungal pathogens in the field. Study showed Sprit cultivar was more resistant than others to all three common pathogens and Lady-Claire was most susceptible. Yield production of Sprit per unit of land area was also exceeded that of other cultivars by factors of 1.10 to 2.25 respectively. The results of the study helped potato growers to culture Sprit cultivar and have good yield production in Zanjan and Hamedan provinces in this year.

Wilting of date palm branches by Fusarium oxysporum in south of Iran and its control managements with soil solarization method.

Wilting of some branches in nurseries and orchards of date palm were studied in south of Iran including Ahvaz and Abadan cities in 2005-2006 years. Different infected plants were visited and samples showing symptoms including wilting or death of branches collected from various areas and transferred to laboratory. Samples were cultured in common media (PDA) and different fungi were studied and identified. The most frequently isolated pathogen was Fusarium oxysporum which caused wilting of some branches of date palm seedling or trees in studied areas. Results showed that the disease caused main losses where date palm cuttings were cultured in infected soils, previously cropped to susceptible plants. Since chemical control was not managed the disease, soil disinfestations by soil solarization method was carried in Ahvaz as the warmer climate in studied areas to control the pathogen. Application of this method reduced population density of the pathogen from 1800 CFU -g/soil to 600 after 5 week. This method was simple, effective, non negative side and economic which can be used in nearly warm areas.

Mycotoxin producing Fusarium species associated with plant disease on potato, wheat, corn and animal diseases in northwest Iran.

There were some plant diseases on potato, wheat, corn, bean and animal diseases such as feed refusal, weight loss, death of cattle and sheep as well as chicken mortality in northwest Iran. Infected plants were collected and cultured in PDA as common medium and Peptone PCNB Agar (PPA) as selective medium for Fusarium species after surface sterilization with sodium hypochlorite. Several Fusarium species were isolated from samples counting potato tubers, wheat, corn, plant residues and animal feeds in the fields and storages. Actually, Fusarium species were the major pathogens causing significant diseases on potato, bean, wheat, corn, rice and alfalfa as the key human food and animal feed in that areas. Study showed most plant and animal diseases especially chickens mortality were attributed to feeding infected plant straw and contaminated feeds in considered areas. Mycotoxin producing species including F. solani, F. oxysporum, F. graminearum, F. moniliformei, F. sambutinum, F. culmorum and F. equiseti were dominant recognized isolates. The common Fusarium mycotoxins such as zearalenone, moniliformin and fusaric acid have been also discovered from these species. The results put emphasis that Fusarium contamination of feeds or foods can be capable of the harmful consequences on animal and human health.

Verticillium wilt of olive branches in Iran and its control managements with soil solarization method.

Wilting of mostly one branch in nurseries and newly established orchards of olive was studied in eastern north of Iran including Zanjan, Golestan and Khorassan provinces during 2002-2004. Different infected plants were visited and samples showing symptoms including wilting or death of branches collected from various areas and transferred to laboratory. Samples were cultured in common media (PDA) and different fungi were identified. The most frequently isolated pathogen was Verticillium dahliae which caused wilting of mostly one branch of olive seedling or trees in studied areas. Results showed that the disease caused main losses where olive cuttings were cultured in infected soils, previously cropped to susceptible plants. In fact, the population density of V. dahliae was high in the garden soil, previously produced susceptible crop cultivar to the fungus especially cotton or potatoes. Soil disinfestations by soil solarization method was carried in Taroam as the warmer climate in studied areas to control the pathogen. Application of this method reduced population density of the pathogen from 1700 CFU g/soil to 1000 after 4 weeks. This method was simple, effective, non negative side and economic which can be used in nearly warm areas.

Severity of walnut anthracnose and its relatively resistant in Iran.

Walnut black spot or Anthracnose has been a destructive disease of Juglans in Iran mainly northwest of the country. Current situation of the disease was studied in various regions including Qazvin, Zanjan, Hamedan and East Azarbyjan provinces during 1999 to 2002. Infected samples such as leaves, fruits and foliage were collected and cultured in PDA, CMA and NA media after surface sterilization with sodium hypochlorite. Morphological characteristics and asexual reproduction of isolated pathogen showed that the fungal causal agent was Marssonina jglandis (Lib) Magn. which perfect stage was Gnomonia leptostyla (Fr). The disease was severing under studied areas, especially when it was rainy and humidity. Virulence of the disease caused major defoliation in some walnut trees infected to anthracnose disease. So, investigation showed that the collecting or burning infected leaves and fruits under trees could reduce severity of disease. Study also resulted there was a resistant variety around the Qazvin province traditionally called "Alamoty" which had not any anthracnose infection in natural condition. The result of experimental work with inoculation of different walnut clones by spore suspension (10(5)) in glasshouse has also indicated that this original clone was more resistant than others to anthracnose disease. Alamoty clone had favorite yield production and some trees presented more than 250 years old in Iran.

Vegetative compatibility and pathogenecity of Verticillium dahliae kleb. isolates from olive in Iran.

Verticillium wilt caused by Verticillium dahliae is a serious problem of olive trees leading to significant reduction in yield. Verticillium wilt of olive trees was first recorded in Iran 1996 and confirm as due to Verticillium dahliae Kleb. 101 isolates of V. dahliae from olive trees at deferent locations in north provinces of Iran were assigned to vegetative compatibility groups (VCGS), using nitrate non-utilizing (Nit) mutants. A higher frequency of nit 1/nit 3 mutants (93%) was obtained compared with NitM (7%) with 10% of the isolates being assigned to VCG1 and 51% VCG4B and 19% VCG2A. 20% of isolates could not be classified in standard isolates. The pathogenecity of 15 randomly selected isolates (5 of each VCG) was tested on olive seedling (cv. Zard) and eggplant. The VCGs isolates were similarly aggressive on olive. However, VCG1 isolates were more aggressive on eggplant cv. Local than the VCG2A and VCG4B isolates as indicated by a higher colonization index. The pathogenecity tests of the pathogen on test plants (cotton cv. 'sahel', eggplant cv. 'local' and tomato cv. 'ps') show all isolates category in 2 pathogenecity groups defoliate and non-defoliate (with severe and mild subgroups). The morphology of V. dahliae isolates on C'zapeck's agar and water agar medium were different especially for microsclerotia appearance time in culture and their morphology.

Olive verticillium wilt or dieback of olive in Iran.

During 2000--03, different areas in Zanjan, Golestan and Khorasan provinces were surveyed for the presence of olive dieback. Olive branches, leaves and roots showing typical symptoms and soil around the roots were collected for further study. Samples were surface-sterilized with sodium hypochlorite or ethanol and then cultured on PDA and Czapek media. Soil samples were diluted in ethanol-agar for fungal isolation and purification. Morphological characteristics of the fungal mycelium particularly phialide and spores identified the causal agent to be the soil-borne pathogen, Verticillium dahliae. The disease was present in all olive growing regions but it was severe in temperate and relatively humid regions such as Gorgan. Infection index of the disease varied between 5 to 30% with an average of 11.89+/-1.12 among various orchards in this area. The newly established orchards showed more infection than the older ones. A significant difference in disease incidence and severity were observed among olive cultivars of Michen, Roughani, Zard and Koronakei. The latter cultivar had the least amount of infection. Strains of V. dahliae isolated from olive trees had different morphological and pathogenicity characteristics. These strains had different growth rates in response to the optimum temperature of 20 or 25 degrees C. The number of fungal propagules per gram of air-dried soil ranged from 2 to 32 with an average number of 13.42+/-0.50. Regarding the number of propagules of V. dahliae in the soil and susceptibility of cultivars in the newly established orchards, it seems necessary to take serious control measures to prevent disease spread.

The occurrence of root rot and crown rot of rice in Gilan and Zanjan provinces, Iran.

Root rot and crown rot of rice is one of the important fungal diseases of rice in Gilan and Zanjan provinces, Iran. During 1999--2002, samples of plant and soil around the roots of infected rice plants were collected and used to identify the causal agent. Root and crown parts were surface sterilized with sodium hypochlorite and then cultured on PDA (potato dextrose agar), PPA (pepton pentacholoritobenzene agar) and CLA (carnation leaf agar) media. Soil samples prepared in water agar were used to isolate the pathogen. The causal agent was identified as Fusarium moniliforme. Colonies were initially white but turned violet to grey late. Microconidia were arranged in chain and macroconidia were cylindrical and long with 3-5 septa. The disease was severe in Zanjan province particularly along Ghezel Ozan river where the infection ranged from 70-80%. Root and crown rot was more prevalent in areas where Champa and Gerdeh were being cultivated continuously. On the other hand, Sadri cultivars had relatively less infection. Persistent cultivation of rice and seed sowing method intensified disease development and caused significant economic losses.