مجله دانش گیاه پزشکی ایران
سال چهل و چهارم شماره 1 (پاییز و زمستان 1392)

Many powdery mildew fungi occur as anamorphic state on different host plants in Guilan province، Iran. The species have usually been identified as Oidium spp. In order to identify teleomorphic species using anamorphic characteristics and host range، several infected plant specimens were collected from around Guilan province during 2004-2011. Based upon the results of the study 25 species were collected and identified. The identified species are as follows: Erysiphe cf. alphitoides on Quercus sp.، Erysiphe australiana on Lagerstroemia indica، Erysiphe begoniicola on Begonia multiflora، Erysiphe betae on Dysphania ambrosioides، Erysiphe convolvuli on Convolvolus sp.، Erysiphe euonymicola on Euonymus japonicus، Erysiphe heraclei on Petroselinum hortense، Erysiphe polygoni on Polygonum persicaria، Erysiphe platani on Platanus orientalis، Erysiphe quericicola on Quercus sp.، Erysiphe sesbaniae on Sesbania punicea، Golovinomyces ambrosiae on Zinnia sp. and Dahlia sp.، Golovinomyces artemisiae on Artemisia annua، Golovinomyces biocellatus on Mentha sp.، Golovinomyces montagnei on Silybum marianum، Golovinomyces depressus on Arctium lappa، Golovinomyces orontii on Nicotiana tabacum، Golovinomycescf. orontii on Fraxinus sp.، Golovinomyces sonchicola on Sonchus sp.، Podosphaera aphanis on Agrimonia eupatoria، Podosphaera euphorbiae-hirtae on Pedilianthus sp.، Podosphaera fugax on Geranium dissectum، Podosphaera xanthiis. l. on Dichrocephala sp.، Gerbera sp.، Physalis alkekengi and Vigna unguiculata، Podosphaera pannosa on Rosa sp.، Sawadaea bicornis on Acer sp. Among The identified species Erysiphe australiana and Podosphaera euphorbiae-hirtaeare recorded for the first time from Iran. Moreover، Erysiphe alphitoides on Castanea sativa، Erysiphe betae on Dysphania ambrosioides، Erysiphe heraclei on Petroselinum hortense، Podosphaera xanthiis. lat. on Dichrocephala sp.، Gerbera sp.، Physalis alkekengi and Vigna unguiculata، Golovinomyces ambrosiae on Zinnia sp. and Dahlia sp.، Erysiphe heraclei on Petroselinum hortense، Golovinomyces cf. orontii on Fraxinus sp. are newly reported on these host plants from Iran. In addition، Golovinomyces montagnei، Erysiphe begoniicola and Erysiphe euonymicola are accepted as correct nomenclature for causal agents of powdery mildew on Silybum marianum، Begonia and Euonymus respectively.

Beet armyworm،Spodoptera exigua (Hübner) (Lep.: Noctuidae)، is a polyphagous insect pest inflicting substantial economic damage to many crops including corn، cotton، beet، tomato، celery، lettuce and alfalfa. In this study the effect of 10 commercial hybrids of corn (SC700، DC370، SC704، SC260، SC500، Keynes540، Keynes410، KSC260، KSC400 and KSC301) on the beet armyworm was investigated through a comparison of the feeding indices of the pest as on these hybrids. The experiment was conducted in a growth chamber set at 25±2 oC، 65±5 % RH and a photoperiodism of 16:8 (L: D) hours. Different larval instars of the beet armyworm (third، fourth and fifth instars) demonstrated the highest (33. 40%) vs. the lowest (2. 95%) values of Efficiency of Conversion of Ingested food into biomass (ECI) on hybrids SC260 and Keynes 540، respectively. The highest (60. 52%) vs. the lowest (3. 01%) efficiency of conversion of digested food into biomass (ECD) were obtained on hybrids SC260 and Keynes540، respectively. The highest (9. 96) vs. the lowest (1. 42) Consumption Indexes (CI) were observed on hybrids Keynes540، and SC260، respectively. Index of Relative Growth Rate (RGR) was the highest on hybrid SC500 (6. 74) while the lowest on hybrid KSC260 (0. 54). Relative Consumption Rate (RCR) of S. exigua was the highest on hybrid Keynes540 (1. 06) while the lowest on KSC260 (0. 17). The results finally revealed that Keynes540 was a partially resistant hybrid as compared with the other ones، tested in feeding of different larval instars of S. exigua.

Tan spot disease of wheat with the causal agent of Pyrenophora tritici-repentis is a very serious disease throughout the world causing severe yield losses. Out of 163 isolates of the pathogen، collected from Golestan and Mazandaran provinces، 58 were selected for a study of population genetic structure. Selecting the real representatives from the whole population was carried out according to the results of the rep-PCR with BOX primers، and as well the locations of the isolates and the fields where the isolates had been collected. Population genetic structure of the pathogen was evaluated using rep-PCR as a molecular marker with three primers namely BOX، ERIC and REP. Three softwares of POPGENE، NTSYS-pc and GenALEx6 were utilized for data analysis. Population structure study among six sub-populations of the Iranian isolates revealed that 73% of the total variance was related to the variations within sub-populations while 27% of that related to the variance among sub populations. Mean gene diversity of the population was estimated as 0. 3147. A dendrogram، based upon genetic similarity with Dice coefficient and UPGMA method showed no clear separations among isolates belonging to different races 1 and 2، so racial distribution of isolates is not found consistent with rep-PCR classification of the isolates in the dendrogram. There exists some consistency between geographical origin of the isolates and their genetic similarity. This is the first study covering population genetic structure of P. tritici-repentis in Iran. An evaluation of telemorph production regarding the pathogen، showed that pseudothecia (with asci and ascospores) were produced for 54% of the isolates while 17% of the isolates produced pseudothecia without asici and 29% while produced no sexual structures. It seems that beside the MAT gene and some other independent genetic factors، some macronutrients as well as humidity effect telemorph production.

The aim followed in this study was to gain accurate information regarding the development and reproduction of sugarcane whitefly، Neomaskellia andropogonis (Corbett) at four constant temperatures of 20، 25، 30 and 32±1°C، 55±5 % relative humidity and photoperiodism of 12h light to 12 h dark to determine the most suitable temperature for development and reproduction of the insect. Egg to adult developmental time of female ranged from 53. 23±0. 22 days at 20°C to 20. 24±0. 09 days at 30°C. A total of 357 degree-days was required to complete development above the lower thermal threshold of 13. 52°C. Pre-imaginal mortality was 51. 6، 27. 5، 14. 16 and 13. 33% at 20، 25، 30 and 32°C، respectively. Mean longevity of female N. andropogonis ranged from 9. 66±0. 35 days at 20°C to 4. 14±0. 46 days at 32°C. Mean total fecundity ranged from 20. 42±1. 94 at 20°C to 61. 25±4. 71 eggs/female. Intrinsic rate of increase (rm) ranged from 0. 053±0. 00 at 20°C to 0. 210±0. 00 (Individuals per female per day) at 30°C. The shortest doubling time was 3. 30±0. 14d occuring at 30°C، while the longest 13. 06±1. 74d occuring at 20°C. The highest reproduction occurred at 30°C. The results obtained from the study are indicative of two useful aspects. First، the best temperature for mass production of the insect (to evaluate the effect of different biological control agents) was determined. Second، by a comparison of calculated parameters of N. andropogonis and those of biological control agents (under the same laboratory conditions) the efficiency of different biological control agents on the insect could be predicted.

In order to study the residue of diazinon in sour grape under filed conditions، an experiment was conducted during spring and summer 2011. The farm experiments were conducted at Khorassan Razavi Research Station (Mashhad). Diazinon was applied to a local variety of the vine called Keshmeshi Ghoochan at two time intervals (23 days apart from each other) with two doses: recommended dose (0. 9 g a. i. L-1) and double dose (1. 8 g a. i. L-1). The farm experiment was conducted as based on RCBD of three replications. Sampling was done at 0، 1، 2، 5، 8 and 12 days following the second spray (sour grape stage). Extraction and clean-up procedures were done as based on solid phase extraction. Quantification analysis of the residues was carried out using gas chromatograph apparatus equipped with nitrogen-phosphorus detector. Results revealed that most of the diazinon was dissipated (under environmental conditions) within the early days of spraying، with its half-life for the recommended and double doses being 1. 5 and 1. 21 days respectively. The dissipation rate of diazinon in the double dose application occurred faster as compared with the recommended dose and no significant difference was observed between the application rates within the last days. Samples taken before the second spray showed no diazinon residues، meaning that all the pesticide had dissipated within the 23-day period following the first spraying operation.

In the course of the present study several diseased insects along with some specimens suffering from disease symptoms were collected and examined. The clinical and microscopic examinations led to isolation and identification of four insect pathogens، all new to the protozoan fauna of Iran. The identified species are listed as follows: 1- Gregarina acridiorum Leger، 1893 from Dociostaurus maroccanus Thunberg، 1815 and Calliptamus italicus L.، 1758 (Orthoptera: Acrididae). 2- Gregarina confusa Janovy et al.، 2007 from Tribolium confusum Jacqulin du val (Coleoptera: Tenebrionidae) a cereal grain coleopteran pest 3- Adelina tribolii Bhatia، 1937 from Tribolium confusum Jacqulin du val and T. castaneum Herbst. 4- Malamoeba locustae King & Taylor، 1936 from Chorthipus brunneus Thunberg، 1815 (Orthoptera: Acrididae).

During the growing seasons of 2009 and 2010، same tomato fields throughout Marvdasht were visited and 96 isolates of Fusarium spp. were collected from root، crown and stem of diseased tomato plants. Isolates were identified as based on morphological characteristics. They were divided into four species namely: Fusarium solani، F. pseudoanthophilum، F. oxysporum and F. equiseti. These species، being highly pathogenic to tomato، accounted for 47. 9%، 18. 7%، 22. 9% and 10. 4% of the isolates، respectively. Of these species، F. solani and F. pseudoanthophilum are the first time reports of on the disase tomato from Iran. The most frequently encountered species were F. solani and F. oxysporum with 46 and 22 isolates، respectively. Pathogenicity test was conducted for all the species of Fusarium on tomato seedlings by the methods of root dip and soil inoculation and as based upon completely randomized design. Data were analyzed through SAS and mean comparison done through LSD test. Results indicated that all the species of Fusarium except F. pseudoanthophilum caused wilt، chlorosis and root rot in tomato host plants. The results indicated isolates of Fusarium spp. To be significantly different in the disease severity at 1% probability. Host range study with F. oxysporum revealed that the pathogen caused wilt and chlorosis only on tomato and was identified as F. oxysporum f. sp. lycopersici. Thid was while، F. solani caused root rot in tomato، chickpea، Arachis hypogea and Amaranthus retroflexus.

Weevils of the genus Larinus feed on the capitula of the host plants from the family of Asteraceae، and are useful in prevention of reproduction of these weeds. Throughout the present study، the species of the genus Larinus were collected from six host plants of the family Asteraceae through timely samplings in 2010 and 2011. The seven species of the genus Larinus namely L. affinis، L. nidificans، L. onopordi، L. syriacus، L. grisescens، L. liliputanus، and Larinus sp. were collected from the tested host plants. TheShannon diversity index for Larinus species on three host plants Echinops aucheri، E. longipenicillatus and Cousinis stocksii was lower as compared with the other studied host plants. Morisita-Horn similarity index for Larinus combinations on E. aucheri، E. longipenicillatus، C. stocksii and as well on other tested host plants varied from 0. 02 to 0. 31. These results indicated that Larinus species combinations are not identical among the six tested host plants، since the highest abundance of the weevils L. affinis، L. nidificans and Larinus sp. were observed on the host plants E. aucheri، E. longipenicillatus and C. stocksii، respectively. Therefore، it can be concluded that the weevils L. affinis، L. nidificans and Larinus sp. are of the potential to be respectively utilized in control of the host plants E. aucheri، E. longipenicillatus and C. stocksii، in Kerman region.

Biological control agents cause induction of systemic resistance through an array of elicitors. In this work، the role of some synthetic compounds in Bacillus subtilis GB03 volatiles، profile was assessed on either direct inhibition or induction of systemic resistance against B. cinerea in Arabidopsis. In comparison with control، all the compounds not only did not suppress fungal sporulation but also increased it significantly. Maximum effects on sporulation were obtained by 3-pentanol and methyl salicylate with 4. 7 ×105 and 4 ×105 spore/ml، respectively. Most of the compounds promoted fungal growth، the highest rates of which were recorded in case of methyl jasmonate and methyl salicylate with respective 23 and 24 percent. Interestingly، minimum vs. maximum of pigment production was also recorded for methyl jasmonate and methyl salicylate، respectively. In induction of resistance experiment، 3- hydroxy-2 butanol، methyl jasmonate، butanediol، acetone and 1-pentanol exerted the highest effect in suppression of disease on Arabidopsis. Methyl salicylate and 3-pentanol، known for their stimulation of defense against biotrophs did not show any noticeable effect in suppression of this necrotrophic pathogen. Eventually، efficiency of the compounds is dependent upon their doses and in low dose they mainly act as signalling molecule rather than direct inhibitor of fungi.

Two-spotted spider mite (Tetranychus urticae Koch)، is one of the most seriously important polyphagous pests that causes considerable damage to agricultural crops. In recent years، due to problems associated with the use of synthetic pesticides، herbal essential oils have received due attention as natural plant pest control compounds. In the present study، repellency effect of herbal plant essential oils extracted from some Lamiaceae family members namely: rosemary (Rosmarinus officinalis L.)، savory (Satureja hortensis L.)، and peppermint (Mentha piperita L (. were studied on T. urticae employing Twin Towers Bioassay (TTB) method. The experiments were conducted at 23±2°C، 60±5% relative humidity and fully light photoperiodism. Bioassay experiments were carried out at 0. 043، 0. 073، 0. 326 and 0. 348 µL/cm2 doses of the essential oils within four experimental intervals of time. The results indicated that peppermint essential oil had the most repellent effect (91%) on female adults of T. urticae at highest dose (0. 348 µL/cm2)، but there was no significant difference observed between peppermint oil and the oils extracted from other herbal plant. (P> 0. 05). In addition، the most persistency was observed for savory essential oil. Throughout the study، a new method was also introduced to evaluate the repellency effect of essential oils on some such herbivorous arthropods as mites.

Common Bacterial Blight (CBB) of bean caused by Xanthomonas axonopodis pv. phaseoli is a seriously important disease that adversely affects the quantity and quality of seed. Cultivation of resistant cultivars is the most effective method of the disease control. To identify disease resistant genotypes of selected beans، an experiment was conducted in Agriculture and Natural Resources Research Center of Markazi province. A number of 10 genotypes were identified as resistant and semi resistant to CBB. Line 31118 was found out as the most resistant. Four of the 10 Lines namely 21400، 21320، 21407، and CIAT check 2 were either resistant or semi resistant to CBB with yields higher than average in either infected or noninfected by CBB. They were introduced as the top genotypes.

Greenbug، Schizaphis graminum (Rondani)، is a major pest of small grains، particularly wheat in Iran. The most effective method to control this insect pest is the use of resistant varieties and lines. In this research، 57 wheat varieties were screened at either two or three leaf stage، as based upon the mean number of aphids on plants. Antixenosis experiment was conducted through counting the number of aphids attracted to each plant variety. In the antixenosis tests after 24، 48 and 72 hr past from the experiments. the highest number of aphids were observed to be attracted to Sepahan variety while the lowest numbers attracted to Omid and Aadl varieties. Tolerance mechanism was assessed as based upon the height of the plant where the aphids were feeding on، and as well upon the decrease in the plant''s percentage of dry and wet weight. Aadl and Omid varieties were found out as the most tolerant varieties to S. graminum. The two varieties exhibited the highest tolerance and were the least preferred hosts as regards S. graminum.

Surveys were conducted to detect and determine the distribution of Prunus necrotic ringspot virus (PNRSV) in stone fruits during the spring 2008 to the end of December 2009. A total of 343 symptomatic and asymptomatic leaf samples were randomly collected from some gardens in Jahrom county of Fars province and Minoodasht and Kalaleh counties of Golestan province. Samples were analyzed by Triple-antibody sandwich (TAS) -ELISA and Dot-immunobinding assay (DIBA) methods using specific mono and polyclonal antibodies prepared by (Agdia، U. S. A، Inc) for the presence of PNRSV. Results indicated that PNRSV distributed with the infection rate of 15. 5% through the visited gardens in Fars and Golestan provinces. It was also showed that surveyed gardens in Jahrom county of Fars province were 16. 4% infected with the PNRSV. It was also detected with an incidence rate of 13. 6% in each of Kalaleh and Minoodasht counties of Golestan province. Mechanical inoculation was performed to inoculate the herbaceous plants at greenhouse. Results were in agreement with what has been reported for the biological properties of PV-32 strains of PNRSV before. Using with the RT-PCR and amplification of the movement protein (MP) gene specific for PV-32 and PV-96 isolates، total RNA extracts from infected leaf tissues were tested. The expected 283bp DNA fragment specific for PV-32 strains of PNRSV was obtained from all the samples tested. Altogether، results of this study showed that detected isolates of PNRSV are close similar to isolates in PV-32 group of this virus.

Rose minor larva، Allantus viennensis (Schr.) is one of the serious pests of roses in Guilan province. The young larvae feed gregariously on the parenchyma of the youngest leaves as they grow، eventually eating the entire leaf parts except the main rib. Glucosidases α- and β- play important roles in the final stages of the insect''s carbohydrate digestion. The effect of pH and temperature were investigated on α- and β-glucosidase activities. Results revealed high α- and β-glucosidase activities at pH 6. Also، optimum temperatures were recorded 40 and 50 °C for α- and β-glucosidase activity، respectively. The specific activity of α- and β-glucosidase in digestive system of the 2nd، 3rd، 4th، and 5th larval instars and in the foregut، midgut and hindguts were also determined. Results indicated that with an increase in the larval instar، the α- and β-glucosidase specific activities were also increased. The α- and β-glucosidase specific activities were higher in the midgut than those in the fore، and hindguts. The α- glucosidase specific activities in the digestive system of the 2nd، 3rd، 4th، and 5th larval instars، and as well in the foregut، midgut and hindguts were higher than those for β-glucosidse specific activities. KM values of α-glucosidase، and β-glucosidase were recorded as 2. 72 and 2. 02 mM، respectively. Zymogram analysis revealed the existence of one form of enzyme in each of the α- and β-glucosidases in the insect''s alimentary canal.

The common pistachio psyllid، Agonoscena pistaciae Burckhardt and Lauterer، is a serious insect pest of pistachio trees where both adults and nymphs suck leaf sap. Their feeding causes reduced plant growth، falling of fruit buds and consequently poor yield. A. Pistaciae is a high potential for development of resistance to insecticides due to its short life cycle along with high potential for reproduction. In this study the susceptibility of A. pistaciae to amitraz and imidaclopride were tested under laboratory conditions. Nine A. pistaciae populations namely: Rafsanjan، Anar، Bam، Kerman، Shahrbabak، Sirjan، Heart، Pariz، and Paghaleh County were collected from pistachio orchards. Insecticide toxicity was evaluated through dip bioassay using technical insecticides up to 5th instar nymphs. Bioassay results revealed that these populations were of varied levels of susceptibility to the pesticides، in a way that the lowest vs. the highest LC50 values for amitraz and imidaclopride were determined، in the Bam (13. 9 & 17. 1 mg L-1) and in Rafsanjan (310. 5 & 46. 3 mg L-1) populations، respectively. From among the field collected populations، the highest levels of resistance to amitraz (22. 3-fold) and to imidaclopride (2. 7-fold) pesticides were detected for the Rafsanjan population. Glutathione s-transferase gel activity was evaluated through a comparison of gel electrophoresis profile among populations. Based on band pattern، some differences were observed in band concentration and the relative mobility between Rafsanjan and Bam (susceptible) populations.

Rice blast caused by Pyricularia grisea (Cooke) Sacc. is one of the most serious diseases of rice throughout the world، which is generally controlled by fungicides. Appropriate selection of sprayers with respect to the field conditions، increases the efficiency of pesticide application and reduces the environmental pollution. In this study the efficiency of five different types of sprayers namely: two types of knapsack micronair sprayers (Model: KP 4000-N10، and SKN-3000) as well as two types of electrostatic sprayers (Model: motorized knapsack mist blower sprayer equipped with electrostatic head and Model: GPS-5 TM) were compared with hydraulic motorized sprayer carried on trolley using two doses (1 and 0/75 kg/ha of tricyclazole (Beam® WP 75%) applied on rice blast disease. The factorial experiment was carried out based upon a Randomized Complete Block Design (RCBD) of 3 replications. The results demonstrated that motorized knapsack mist blower sprayer equipped with electrostatic head، hydraulic motorized sprayer on trolley (conventional sprayer) as well as knapsack micronair sprayer (Model: KP 4000-N10) were of the highest efficiencies. The mean severities were estimated 1. 67±0. 13، 2±0. 12 and 3. 5±0. 33 respectively. The pesticide solution taken up by the 3 sprayers were recorded as 48، 450 and 65 L/ha. respectively. This shows considerable reduction in the level of fungicide applied in the motorized knapsack mist blower sprayer equipped with electrostatic head and in knapsack micronair sprayer، leading to an increase in efficiency and decrease in operating costs. Evaluation through water-sensitive cards indicated that motorized knapsack mist blower sprayer (with electrostatic head) and knapsack micronair sprayer (Model: KP 4000-N10) led to a better distribution of droplets than hydraulic motorized sprayer carried on trolley did. It is recommended that the above mentioned technique be only applied to leaf rice blast، since it can not be beneficial to the crop when it is at its panicle stage and tall.

Fluorescent pseudomonads are known as some most beneficial biocontrol agents for controlling root disease because of producing a broad spectrum of antibiotics and their effective root colonization at the right time and at the right place. In this regard، the colonization patterns of four Pseudomonas fluorescence strains were investigated in 5، 12، and 21 days following sowing bacterial coated seeds in 800 gr pots، containing garden soil mixed with 8% inoculum of Gaeumannomyces graminis var. tritici (Ggt) the agent of take-all disease. Bacterial population was determined through a counting of colony forming units (cfu) at upper، middle، as well as lower parts of wheat root. The statistical relation between colonization pattern of root and the index of take-all disease was found out، studied and analyzed. The results indicated that bacterial populations are varied within different times and at different zones of the root. During the first stage of sampling the bacterial population was higher in the upper and middle parts، whereas within third time the bacterial population decreased in upper and middle parts while being increased at the lower parts of the root. The relationship between colonization pattern and disease index revealed that bacterial population significantly affect the reducing of disease intensity. The most effective bacterial population، in reducing disease intensity، was observed for mass colonization at the root apex (r2 = 0. 99. 6). It can be concluded that better and greater potential for colonization of root apex by the four tested strains is in close relationship with their ability to control take-all disease، this playing a key role in successful control of the disease by these strains.