نشریه پژوهش های کاربردی در گیاه پزشکی
سال یازدهم شماره 2 (تابستان 1401)

 In this study, ninety- six isolates of Pyrenophora tritici-repentis from Ardabil province were collected and identified. According to the results of molecular data and considering the geographical area, thirty isolates were selected for race identification studies in greenhouse. Genetic diversity was detected between three fungal populations including Parsabad, Germi and Bilesavar in Ardabil province. During the study of gene diversity, the amount of gene flow (Nm) was equal to 1.6890 and the amount of Gst was equal to 0.2284. The rate of genetic diversity for the whole population (Ht) was 0.2993. PhiPT was estimated to be 0.259 (p> = 0.010). According to the results of AMOVA, 74% of total variance was attributed to within populations while only 26% of that was related to between populations. Race1 of the pathogen as the main race was used in Ardabil province to evaluate the resistance of forty wheat cultivars in greenhouses. Inoculation was carried out using fungal conidial suspensions and fungal culture filtrates. The Mean Disease Index in different cultivars was calculated and compared. The results of cultivars' reaction showed that 90% of studied wheat cultivars are in the susceptible group to the pathogen. Four cultivars of Morvarid, Moghan 3, Ehsan and Darya, which together comprise 10% of the studied cultivars, were included in the resistant group. The use of these resistant cultivars is recommended for areas with a high possibility of disease outbreaks. In addition, breeders can use the sources of resistance for future breeding programs.

Olive peacock spot disease caused by Venturia oleaginea is the most important fungal disease of olive trees worldwide, which in areas with high levels of infection the use of fungicides for disease control is inevitable. This study was conducted to evaluate the effectiveness of several different fungicides and to determine the best spraying times for chemical control of the disease in the Tarom region of Zanjan province during two years. In the first year, the efficacy of three known strobilurin group of fungicides (Stroby®, Flint® and Nativo®) in comparison with three copper fungicides (Bordofix®, Mishocap® and Nordox®) in three-time treatments on November 6, March 6 and April 6 in factorial experiment was examined. In the second year, the effectiveness of four fungicides of Nativo, Thiophanate Methyl, Mancozeb® and Nordox with four spraying times on November 6, December 6, March 6 and April 6 was evaluated in a randomized complete block design. The results of this study showed that the studied strobilurin group of fungicides provided the necessary efficiency in control the damage of peacock spot disease in severe infection conditions. In contrast, copper fungicides did not have promising results. Nativo fungicide had the best performance in controlling the disease in the first year with 61% and in the second year with 63% reduction in the incidence of the disease compared to the control. November spraying had the maximum effect and April spraying had the least effect in reducing the damage of the disease. However, at least three sprays are required for acceptable control of the disease.

 Pistachio fruit moth is one of the most important pests of pistachio orchads. In spite of severe damage of this pest in some orchards, the variety of recommended pesticides against it is very limited. Oxydemeton-methyl and fentione have been registered and recommended against this pest. Low efficiencies of these compounds and also the harmful effects of these pesticides on natural enemies are the problems of using these insecticides. In this study, the efficacy of two avermectine based compounds including abamectin and emamectin benzoate+lufenouran, which are effective on the larvae of some lepidopterous pests were tested against pistachio fruit moth. The experiments were performed in two consecutive years in a Randomized Complete Block Design (RCBD) with different doses of the insecticides. To evaluate the effect of pesticides on the pest, dried and damaged seeds by larvae of pest were counted 7, 12, 18 and 25 days after spraying. The final number of seeds per cluster was also recorded and the efficiency of treatments was calculated. The results showed all treatments were effective against larvae of the moth. In general, higher doses of abamectin (0.4 and 0.6 lit/1000 lit) and higher doses of emamectin benzoate+ lufenouran (200 and 250 gr/1000 lit) were more efficient than other treatments. In general aspects, it seems that abamectin in rate of 0.6 lit/1000 lit is the best treatment for controlling this pest.

The two-spotted spider mite Tetranychus urticae is one of the cosmopolite pests, which attack many agricultural and greenhouse plants. Recognizing the distribution of this mite using climate data can be of great help in better pest management. In this research, the MaxEnt model was used to study potential distribution of two-spotted mite in several stations (orchards) of Razavi Khorasan province. Modeling the distribution of the mite was based on six environmental predictors and presence records including maximum temperature of the hottest month of the year, minimum temperature of the coldest month of the year, average temperature of the hottest season of the year, average temperature of the coldest season of the year, precipitation the warmest season of the year and the coldest rainy season of the year among the 19 climatic variables. ROC curve analysis and the area below the AUC curve was used to evaluate the modeling results. According to the Jacknife test, variables of the temperature of the coldest season of the year, average temperature of the warmest season of the year and minimum temperature of the coldest month of the year were the most contributing in mite distribution modeling in this province and average temperature of the coldest season of the year was more important. The area below the AUC curve equal to 0.75 indicates the model obtained for this species has high accuracy. The area below the ROC curve is 0.75 and for the data used to validate the model is 0.65, which indicates the acceptable detection power of the model.

The parasitoid wasp Trichogramma brassicae is one of the most important natural enemies used to biologically inhibit the egg stage of pests. Rearing of this parasitoid on different hosts and its interaction with entomopathogenic fungi Metarhizium anisopliae is very important in pest control. Therefore, this entomopathogenic fungus along with trichogramma parasitoid can be used in integrated pest management. In this study, effect of M. anisopliae (isolate M14) concentrations on parasitized eggs of Ephestia kuehniella and Sitotroga cerealella, oviposition preference and hatching percentage on the hosts, also, oviposition preference by parasitoid on E. kuehniella and S. cerealella eggs impregnated with different concentrations of M. anisopliae (isolate M14) and control treatment were studied. Probit analysis obtained from the effect of M. anisopliae (isolate M14) concentrations on E. kuehniella and S. cerealella eggs containing parasitoid showed the highest mortality of parasitoid on E. kuehniella. In the host preference test by choice and non-choice methods, the highest number of parasitic eggs and parasitoid hatching were recorded in E. kuehniella. In the study of the effect of different concentrations of M. anisopliae on the parasitized rate of hosts eggs showed that at low concentrations there is no significant difference between treatments and control, but in higher concentrations, a significant difference was observed, and mean of parasitized eggs was higher in the control. The results of present study confirm that in the simultaneous use of two biological agents, more attention should be paid to the interaction between them to control of target pest.

For cost-effective mass production of entomopathogenic fungi, it is necessary to evaluate the effect of a low-cost culture media on condition and virulence of entemopathogenic fungi. The objective of this research was to evaluate the effect of moisture content, substrate and nutritional supplements on condition and virulence of Beauveria bassiana against greenhouse whitefly. The water requirement of B. bassiana A1-1 for mass production on wheat bran, rice bran, corn bran, rice husk, rolled oat, and the used barley residues in insectariums, was initially evaluated at the ratio of 0.5:1, 1:1 and 1.5:1 (distilled water: culture medium). Then, the effect of whey and molasses on the condition of this fungus was evaluated. The virulence of conidia harvested from wheat bran, rice bran, corn bran and barley substrates was also investigated on greenhouse whitefly nymphs in laboratory and greenhouse conditions. Wheat bran and rice bran in water ratio of 0.5:1 (distilled water: culture medium) showed the highest yield with an average of 5.3 × 1010 and 5.1 × 1010 conidia per gram of substrate, respectively. In the test of the effect of nutritional supplements, except to barley substrate, the addition of whey increased the condition in other substrates. In laboratory bioassay, all treatments showed between 80 and 87% mortality, but in the greenhouse bioassays, the produced conidia on rice bran, corn bran and wheat bran caused 56 ± 1.87, 52 ± 2.54 and 49 ± 2.91% mortality, respectively. According to results, rice bran, corn bran and wheat bran are introduced as suitable substrates for mass production of the studied fungal isolate.

Apple stem grooving virus (ASGV) is one of the important viruses infecting apple trees. In this research, 87 symptomatic and symptomless leaf and bark samples were collected from the apple orchards in west and south west of Zanjan and east of Kurdistan provinces to detect ASGV. After total RNA extraction from 50 out of 87 samples, cDNAs were synthesized by reverse primer and PCR optimized using a pair of specific primer corresponding to complete coat protein gene. A DNA segment with 728 bp length corresponding to complete coat protein gene was amplified from twelve samples by RT-PCR. Nine PCR-products including four samples cloned into pTG19 and five samples without cloning were sequenced. The sequencing and blast results revealed that the fragments belong to coat protein gene of Apple stem grooving virus. Phylogenetic analysis of new Iranian isolates and those retrieved from GenBank by MEGA 7 and Neighbor-Joining methods in Jukes-Cantor model showed that the new Iranian isolates were placed in a sub-clade with reported Iranian, Indian, South Korean and Chinese isolates. The result revealed that the least dN/dS ratio belonging to Iranian isolates and the most gene flow was calculated between isolates from Iran, China and South Korean. This is the first report of Apple stem grooving virus from the Zanjan region.

Tomato leaf miner is one of the new and important pests of tomato in Iran and every year it reduces the yield and quality of the product in terms of marketability. Therefore, in order to use insecticides that are safer for the environment, consumers and natural enemies, in this study, the effect of spinosad, imidacloprid, indoxacarb and chlorantraniliprole insecticides on Tuta absoluta was evaluated under field conditions. This study was performed in a randomized complete block design with five treatments, one control and three replications. The results of this study showed that the efficacy of chlorantraniliprole and spinosad was higher than indoxacarb and imidacloprid on the third, seventh, tenth and fourteenth days after spraying. Also, the effect of LC25 of each of the mentioned insecticides on the parasitism rate of tomato leaf miner moth eggs by two species of parasitoid wasps T. brassicae and Trichogramma evanescens was evaluated under laboratory conditions. The rate of reduction of parasitism in spinsad, imidacloprid, indoxacarb and chlorantraniliprole treatments for T. brassicae was 23.73, 18.31, 14.58 and 9.37%, respectively, and for T. evanescens 24.02, 18.65, 13.78, 9.75% was determined. The results showed that chlorantraniliprole was less toxic compared to other compounds studied for parasitoid wasps and compared to other insecticides, the rate of parasitism of two species of Trichogramma was less affected. Hence, its use in integrated pest management programs of T. absoluta is recommended.

To evaluate the effects of Streptomyces bacteria on biocontrol of Tylenchulus semipenetrans in Citrus aurantifolia and Meloidogyne incognita in Actinidia deliciosa, samples were collected from the rhizosphere of citrus and kiwifruit trees in Mazandaran, Guilan, and Golestan provinces. In vitro, 9 Streptomyces isolates showed good antagonistic potential and reduced the rate of egg hatching and larval mortality of citrus nematode and root-knot nematode. Isolates of Streptomyces sp. (C, D, E, G, and H) which had high control ability in vitro were examined in the greenhouse. Among the isolates studied, isolates D and G in greenhouse conditions showed the greatest effect on the control of citrus nematodes by reducing the number of female nematodes by 86.81% and 77.65% compared with the fenamiphos 64.47% Also, these two isolates decreased galls by 67.78% and 71.15% compared with the fenamiphos 50.93% and reduced the number of egg masses by 86.54% ccompared with the phenamiphus 68.90%, had good performance in root-knot nematode control.