نشریه آفات و بیماریهای گیاهی
سال هفتاد و هفتم شماره 2 (پیاپی 89، اسفند 1388)

Potato rhizospher soil and tubers were collected from Hamadan, Damavand and Qasere-Shrin areas. A total of 96 Fluorescent Pseudomonads strains from collected soil and tuber samples were isolated on pseudomonas agar F medium. Based on the antagonistic activity of the fleuoresent pseudomonads strains against Pectobacterium carotovoru invitro, 40 representatives were selected and their phenotypic features were characterized. Phenotypic feature characterizations resulted three species including Pseudomonas aeruginosa, P. Putida and P. fluorescens (bv. II, III & IV). Antagonistic activity assessment of 20 representative's strains of the above species towards Pectobacterium carotovorum the causal agent of potato rot disease invitro indicated that they could inhibit growth of pathogen and siginificant differences among the appllied strains were observed. Based on the results of invitro xperiments six strains were selected. Bacterial suspention from these strains with OD (optical density) 0.1 in 600nm were made in distilled water. The bacterial suspention were diluted 1000 (concentration I) and 10000 (concentration II) times respectively. Potato tubers were sprayed with bacterial suspension and they were put in soil infested with P. carotovorum. Randomized block design in three replicate were used for this experiment. Tested strains showed biocontrol activity towards P. carotovorum and significant differences were observed among their efficacy were observed. They reduced the potato rot disease caused by P. carotovorum between 2.5 to 38.75 %. No significant differences were observed between the two applied concentrations of the antagonistic bacterial suspensions.

Investigation on economic injury level (EIL) of chickpea pod borer Heliothis viriplaca has been carried out during two consecutive years (2001-2002) in Maragheh region, Northwestern Iran. This study was conducted at open field condition (out of cages). Two varieties including Jam and Beevanij were cultured in separately plots (100m×10m). Experiments were conducted on 25 chickpea rows at the middle part of each plot. Ten rows of chickpea at the end of each plot have been considered as control. After oviposition of females in natural condition experimental rows were separated to preventation of larvae transfers. Number of larvae per rows with 4 metre length was counted and amount of crop losses caused by one larva was estimated 0.01463 and 0.00403 Kg. for Jam and 0.1283 and 0.00267 Kg. for Beevanij in high precipitation and normal precipitation years respectively.EIL rates were estimated 0.35 for Jam and 0.4 for Beevanij varieties in high rainfall condition; 1.25 for Jam and 1.9 for Beevanij in normal rainfall years.

Field bindweed has an impressive array of survival techniques which has enabled it to become one of the world’s 10 worst weeds. Throughout the past century, its invasiveness has given major impetus to the development of selective herbicides and weed science in general. This research was accomplished during 2005 to 2006 at Weed Resaerch Department, Iranian Research Institute of Plant Protection for identification of morphoecophysiological variation of field bindweed population, and introducing these weed biotypes in Damavand. The study was done by Principal Component Analysis (PCA) and Cluster Analysis (CA) based upon 43 morphological and physiological variables. The most important variable was Leaf Area (LA). Results of this study showed 16 biotypes in Damavand. The variability in morphological and physiological of field bindweed biotypes may explain their different adaptability as the environmental conditions and different managemant practices change. The reason of difficult control of field bindweed is the high degree of phenotypic polymorphism within this species.

Morphology and life cycle of alfalfa root scale was studied in the field for 2 years from 2003. Alfalfa field was sampled weekly and biology of different nymphal instars was studied in field condition. The cysts were transferred to laboratory and their morphology and biology were studied. The field’s soil was sampled from depth 0-10cm and 10-30cm and its structure, pH and food materials were measured. The scale samples were sent to Plant Protection Research Institute for identeficacion. The investigations showed that this pest owervinters in field condition as first instar nymph (crawler). From mid-winter it transferred to cyst stage. Nymphs feed on the roots of the host until first week of Augest until adult females appear. The female produced an egg sac and laid eggs at a depth of 15 cm of the soil. The eggs hatched from mid-September and the crawlers appeared in the field. The adult males appeared from early September and this scale produced only one generation in a year.

The whiteflies, Bemisia tabaci Gen. and Bemisia argentifolii Bellows & Perring and the leafhopper Empoasca decipiens Paoli are the most serious and polyphagous pests on wide rang of economic crops in Iran and other places especially in tropical regions. Both of the whiteflies in adult stage are too similar to identify them particularly in field conditions, so population fluctuation and spatial distribution of whiteflies as mixed of two species B. tabaci and B. argentifolii with E. decipiens was studied on eggplant crops in Varamin region weekly during 2006. The k parameter, index of dispersion, Lloyd’s mean crowding, Morisita’s index and regression methods (Taylor and Iwao) were used to estimate the spatial distribution pattern of insects. There was improved sampling program by k parameter and coefficients of regression models. Whiteflies were seen one week later than leafhopper in middle of May. The result indicated that the highest population density of B. tabaci + B. argentifolii and E. decipiens was early of June (4.89 per leaf) and early of August (6.69 per leaf). Both of populations were reached to zero in early of October. All of used methods except index of dispersion of whiteflies were shown an aggregated distribution for all species, but index of dispersion for whiteflies was determined random behavior. The reliable sample size (number of leaves) with maximum variance of 20% was about 38 and 20 leaf for whiteflies and leafhopper, respectively. Sampling program was improved by k parameter, 103.37 and 155.42, coefficients of Taylor 14.98 and 0.88 and Iwao’s coefficients 149.39 and 63.35 sample units for whiteflies and leafhopper, respectively. The difference between sample sizes may be due to different precision of indexes. Determining sampling program and spatial distribution pattern of the pest can effectively help to design and perform of IPM.

In order to identify thylenchs species (Superfamily Tylenchoidea and suborder Aphelenchina) in Kerman province, 150 soil and root samples were collected from Kerman province during 2004 and 2005. The samples were washed and the nematodes extracted by centrifugal floatation technique. They were then fixed and transfered to glycerin according to the De Grisse method (1969). The permanent microscopic slides were prepared from the extracted nematodes. Morphological and morphometrical characters of the species were studied by light microscopy. As a resalt, 21 species belonging to several genera Tylenchoidea, three species of Aphelenchides and one species of Stictylus were identified. Among them, Cephalenchus lobus Dhanachand & Jairajpuri, 1980, Coslenchus areolatus (Egunjobi, 1967) Siddiqi, 1978 and Rotylenchus eximius Siddiqi, 1964 are new records for Iran.

In the present research, phenology of Russian knapweed (Acroptilon repens) was studied in an experimental nursery in Department of Weed Research, Iranian Research Institute of Plant Protection, based on growing degree day. The Results indicated that emergened plant of root occurred in 0, to 3823.3 growing day-degree and 8 phenological stages were recorded. These stages were shoot emergence, rosette conversion to main stem, production of secondary shoot, main stem branching, booting, flowering, flower drying, shoot drying. On based of obtained results the production of Russian knapweed seeds was synchronic with booting. The seeds turned into milky stage and maturity 10 days and 30 days afterward. In general, Russian knapweed is a weed with long growth period. In this study, annual period of shoot growth took about 41 weeks (10 months).

Genetic diversity of 39 clones of common reed (Phragmites australis) originating from different geographical areas of Iran was evaluated using RAPD markers. Sixteen primers were used and 149 scorable bands were obtained, among which 123 were polymorphic (81%). Genetic similarity coefficients ranged from 0.44 to 0.85, with an average of 0.60. A dendrogram was prepared on the basis of a similarity matrix of RAPD data using the UPGMA algorithm and separated the 39 clones into four groups which were mainly in accordance with geographical origins. To study the responses of different clones of common reed to glyphosate and to determin the best growth stage for chemical control, a completely randomaized design with three replications was conducted. Three factors including clone of common reed, the glyphosate rate and treatment time were used. Clones responded differentially to glyphosate rates and treatment at flowering stage provided the best control.

The green leafhopper, Empoasca decipiens Paoli (Hemiptera: Cicadellidae) is one ofpests of sugar beet, Beta vulgaris L. in Iran. In this research, life table, reproduction and population growth parameters of E. decipiens were studied on four sugar beet cultivars: Shirin, Rasool, PP8 and IC. The experiments were conducted in a growth chamber at temperature of 25±1ºC, 50-60% RH and a photoperiod of 16:8 (L:D) h. The survival rate of individuals developed into adults from the initial cohort stage was estimated 0.78, 0.81, 0.78, and 0.76 on Shirin, Rasool, PP8 and IC, respectively. The life expectancy was 13.75, 14.89, 14.46 and 15.72 days, respectively at the first day of adult emergence. The highest gross and net fecundity rates were on IC and Shirin, respectively. Gross reproduction rate were 22.03, 20.07, 22.06 and 22.31 female per female per generation, on Shirin, Rasool, PP8 and IC, respectively. Intrinsic rate of increase (rm) were 0.099 and 0.104 (day-1) on Shirin and IC, respectively. The mean generation time (T), net reproduction rate (R0), doubling time (DT) and finite rate of increase (
) on these cultivars were estimated by Jackknife

29.14- 31.75 days, 20.07-22.31 female per female per generation, 6.62-7.01 days, and 1.103-1.110 offspring per female per day, respectively. These results provide important information for demographic parameters of the green leafhopper on different sugar beet cultivars.

The pathogenicity of four isolates of three fungal species against females and cysts of Heterodera schachtii on water agar and the effects of fungal filtrates on motility of secondstage juveniles were examined. Rates of egg colonization by the fungi were measured after 3 weeks at 20 °C on 0.8% water agar. Fungi penetrated both females and cysts of which 60, 36, 21 and 17% of the eggs were infected by the two isolates of Paecilomyces lilacinus (PL 8.1 & PL 25.4), Cylindrocarpon destructans var. crassum and Chaetomium murorum, respectively. Filtrates of the fungi reduced mobility of the nematode J2 after 24 and 48 h incubation periods. Isolate 8.1 of P. lilacinus paralyzed 100% of the J2 after both 24 and 48 h incubation periods. After 48 h of incubation the extracts of isolate 25.4 of P. lilacinus, C. destructans var. crassum and C. murorum paralyzed 25, 22 and 9% of the J2, respectively.

A total of 48 scale insect species (Hemiptera: Coccoidea) are recorded in the central Zagros region (Ilam, Lorestan, Kermanshah and Hamadan provinces). The species belong to 33 genera and 10 families Asterolecaniidae, Cerococcidae, Coccidae, Diaspididae, Eriococcidae, Margarodidae, Kermesidae, Ortheziidae, Phoenicococcidae and Pseudococcidae. Three species Duplachionaspis noaeae (Hall) (Diaspididae), Rhizopulvinaria turkestanica (Archangelskaya) (Coccidae) and Gueriniella serratulae (Fabricius) (Margarodidae) are first recorded for the Iranian fauna. 39 species occur on the forest trees and pastures and 14 species attack on the orchards and crops. The distribution of the identified species is shown that 13 species are restricted to Irano-Turanian region, of which 10 species are found only in the Zagros region. No purely Mediterranean species are so far recorded, but 11 species belonging to a Mediterranian/ Irano-Turanian regions; and 4 scale insect species are restricted in Saharo-Sindian region.