فصلنامه گیاه پزشکی
سال چهل و هفتم شماره 1 (بهار 1403)

Brown rust or leaf rust of wheat caused by Puccinia triticina Eriks. It is considered one of the most damaging diseases of wheat all over the world, including Iran. Brown rust can reduce the yield of wheat in fields by 20 to 50% in epidemic conditions. The fungus that causes brown rust disease due to having a sexual cycle and new genetic recombinations resulting from it (presence of intermediate hosts in most regions), an asexual cycle in favorable weather conditions and Also, the probability of occurrence of phenomena such as mutation, migration and selection pressure by resistance genes in the hosts has high genetic diversity (variety of physiological breeds), genetic flexibility (variability) which by producing new breeds with Completely different pest patterns can overcome the created genetic resistance. The newly created breeds can be quickly transferred from one area to another through the wind and cause an increase in racial diversity in the disease population of other areas. The most reliable and fundamental method of its control and management is the use of genetic resistance. Accurate knowledge of the genetic structure of the pathogenic population in each region is the first step and road map to achieve effective and stable genetic resistance in wheat. This is possible through the monitoring of harmful pathogenic factors on the differential genotypes of brown rust in the trap vaults.

The effectiveness of resistance genes of international differential cultivars of brown rust was investigated in Moghan region of Ardabil province as one of the important poles of Iranian wheat production in two consecutive crop years (2022-2023). To identify the sources of resistance to the existing breeds in the region, the responses of 40 commercial varieties and 40 promising lines of wheat was evaluated. Investigating the resistance response in the full plant stage under natural pollution conditions, by the parameters of pollution coefficient (CI), final disease severity (FDS) and the relative value of the area under the disease progression curve (rAUDPC) in the research station of the Research and Training Center for Agriculture and Natural Resources of Ardabil Province (Moghan) were measured.

The population of breeds in Moghan region were different from each other in both years. The results indicated that in both years of the test, the pathogenic mushroom population had immunity to differential cultivars carrying resistance genes Lr18, Lr19, Lr20, Lr22a, and Lr29. Therefore, these genes have the necessary efficiency to create effective resistance to brown rust pathogenic races in Moghan region. The differential cultivars carrying the resistance genes Lr2a, Lr2b, Lr9, Lr17, Lr21, Lr23, Lr10/Lr27/Lr31, Lr33, and Lr34 also showed relatively acceptable resistance to the pathogenic strains of brown rust in Ardabil region. The reaction of the genotypes carrying these genes was specific to the race. In other words, in one year they had a resistance reaction and in another year they had a semi-resistant to semi-sensitive reaction with an intensity of 5-20% contamination. Commercial cultivars and promising lines of wheat, which had an effective resistance response and the lowest value for the measured traits, as sources of effective genetic resistance to the brown rust pathogenic population in Moghan region and similar regions in The hot and humid climates of the country are introduced, which include Sahar, Rakhshan, Shush, Farin, Sirvan, Araz, Meraj, Danesh, Talai, Sana, Aran, Tirgan, Taban, Hana, Mehrgan, Avan, Arman, Fallah, Tektaz cultivars. and lines N-95-6, N-98-8, S-95-3, S-96-15, S-96-16, S-97-10, S-98-11, S-98- 22, M-97-12, M-97-18, M-98-18, CD-91-12, C-97-4, CD-97-19, C-98-7, C-98-8, They were CD-98-17, MS-92-5, MS-94-5, D-97-15, and D-97-16.

Correct and conscious use of the combination of effective resistance genes identified in this research can create more stable resistance to brown rust. It is possible to use the resistance genes present in resistant genotypes identified in multi-breeding programs for the pyramiding of resistance genes in desirable wheat genotypes in terms of agricultural traits, yield and other physiological characteristics, in the production of stable resistant cultivars. Compared to the disease, he used a brown rust.

Among the different pests of wheat, cereal aphids are considered important pests that cause economic damage at high densities. Induced resistance by using some chemical and natural products can be an effective tool to control these pests in an integrated pest management (IPM) program. In this study, the effects of some potential resistance inducers, salicylic acid (SA), calcium silicate (CaSi), potassium silicate (PSi) and tea aquatic extract, on some cereal aphid populations were investigated under field conditions. Based on the results, almost no significant difference was observed between the potential resistance inducer treatments and the control on most sampling dates. The obtained results showed that there was no significant difference between the yield parameters, e.g., wheat spike length, spike numbers/m2, seed numbers/m2, seed numbers/spike, 1000 seed weight, wheat plant length, total spike weight/m2 and total seed weight/ha, between the potential resistant inducer treatments and the control. The analysis of defensive compounds like hydrogen peroxide and flavonoids, along with the activities of defensive enzymes peroxidase and catalase showed that there is no significant difference in the flavonoid and peroxide contents of plants treated with CaSi, PSi, SA, and tea extract. The peroxidase activity assay also indicated no significant difference among the treatments. Furthermore, although plants treated with PSi showed the lowest catalase activity compared to the other treatments, there was no significant difference in peroxidase activities among plants treated with the resistance inducers and control. Therefore, the study indicated that resistance inducers are not significantly effective in the pest control.

Re-description of Dorylaimellus graminis and new data (morphological, morphometrical, and molecular) for D. globatus and D. (Axodorylaimellus) parvulus are presented from Taf area, Khorramabad, Lorestan province, Iran. These three species are reported for the first time for Iranian nematode fauna. The population of D. graminis is characterized by its 0.8-1.0 mm long body, lip region offset by constriction, 6-8 μm broad with sclerotized pieces around the vestibule, odontostyle 5-7 μm long, neck region 234-290 μm long, pharyngeal expansion occupying 55-57% of total neck length, female genital system didelphic-amphidelphic, vulva longitudinal (V = 54-57), caudal region convex-conoid (33-36 μm, c = 23.0-30.4, c′ = 1.8-2.6), spicules 21-25 μm long, and four spaced ventromedian supplements with a hiatus. The Iranian populations of two other species herein studied don’t have significant differences compared to previously described populations. For the first time, the phylogenetic positions of these species based on 28S rDNA (D2-D3 segment) in this study are presented. Also based on molecular analyses we suggest that the genera Dorylaimellus and Axodorylaimellus are synonymous.

Pseudomonas syringae pv. syringae (Pss) poses a significant threat to agricultural ecosystems due to its broad host range, encompassing over 200 plant species. Disease-causing bacteria infect all aboveground plant organs throughout the season, causing symptoms such as fruit spots, necrosis, dead buds, flower blight, and cankers on stems and branches. The control of diseases caused by Pss is almost impossible because of the lack of effective chemical or biocontrol agents, the low number of resistant cultivars and the endophytic nature of the pathogen. Different pathogenic strains have a large genetic variability adaptable to different hosts, cultivars, and pedoclimatic conditions, making it difficult to control bacterial canker. One of the most viable and economical methods for managing bacterial canker in peaches is to use resistant cultivars. The present study aims to determine the resistance reactions of peach cultivars against Pss.

During 2016-2018, bacterial strains were isolated from stone fruit plants with leaf spot, canker, and gummosis symptoms. Physiological, biochemical, and molecular tests were performed on all isolated strains. To evaluate the resistance of peach cultivars, Pss was inoculated to two-year-old seedlings of different peach cultivars, including Zaferani, Alberta, Anjiri, and Hastejoda. Different pairs of primers were used to detect virulence genes in Pss isolates.

Isolates were rod-shaped, motile, gram-negative, obligate aerobe, oxidase negative, catalase, levan and tobacco hypersensitive reaction positive, arginine dihydrolase, and potato rot negative. Additionally, all isolates harbored the genes responsible for syringomycin synthesis (syrB) and syringomycin secretion (syrD). Based on these phenotypic and genotypic characteristics, along with the results of pathogenicity tests and PCR analysis, all isolates were identified as Pss. Various primers were used to detect important virulence genes in different Pss isolates. The syringomycin synthesis gene (syrB) was detected in all Pss isolates. The sypA gene was detected in Pss strains H2, H3, H4, and H5, and the sypB gene was detected in Pss strains H2, H34, H5, and G1.Moreover, nit gene was detected in H4 and H5 isolates, and ach gene was detected in strains H1, H2, and H4. Pss strains H3, H4, and H5 produced the expected 1128 bp product after amplification with hrmA1 and hrmA2 primers. Four cultivars, namely Alberta, Zaferani, Hastejoda, and Anjiri, were chosen for the study to investigate the resistance of peach plants. Significant variations were observed among the different cultivars regarding the number of necrotic lesions on the leaves and the length of the necrotic regions on the branches. Among the cultivars examined, Anjiri showed the highest susceptibility to Pss, while Hastejoda exhibited the least sensitivity, indicating potential resistance to the pathogen.

Besides its usage for fresh fruit, canned fruit, dried fruit snacks, and fruit juice, peach trees are considered ornamental plants attributed of their white, pink, or red flowers during springtime. Commercial peach production is challenging for multiple reasons. One of them involves its susceptibility to many diseases that can significantly affect fruit yield and quality, and some can also impact the longevity of the trees. The enormous efforts carried out over the last two decades have led us to gain a more in-depth understanding of the P. syringae pv. syringae-host interactions. In Iran, there are no effective treatments for controlling bacterial canker of stone fruits caused by Pseudomonas syringae pv. syringae. Host tolerance to plant pathogens is important for developing cost-effective and environmentally safe strategies for disease management. Similarly, using resistant cultivars in crop improvement is critical since plants and plant products are usually protected from, rather than cured, diseases. Resistant genotypes will allow sustainable control with zero pesticide residues on fruits, improving the safety of harvesting and decreasing disease problems during storage, thereby leading to enhanced economic benefits.

Wheat is a critical crop in Iran and pivotal in food security, economic stability, and political landscapes. Wheat fields are the habitat of many insects, including both beneficial and pest species. Therefore, various insecticides are employed in wheat fields to safeguard crop yields. However, pursuing pest control often entails unintended consequences for non-target organisms, particularly pollinators and natural enemies. This study aimed to evaluate the effect of both chemical and herbal insecticides on non-target insect populations within Iranian wheat fields. Although plant-derived insecticides may offer ecological benefits, the study emphasizes the need to evaluate their efficacy against pests and their impact on beneficial insects. Therefore, it is necessary to consider the possible effects of herbal and chemical insecticides on natural enemies.

This study evaluated the adverse effects of some recommended insecticides for wheat pests on some natural enemies. A completely randomized block design with five treatments and four replicates was employed. The experiment was conducted in Ardabil, Tehran, and Golestan, Iran. The size of each plot was 100m2 (10 x10), with a distance of 2m between blocks and plots. A total of 30 wheat stalks were randomly selected for sampling in each plot, and all larvae on these stalks were counted within the wheat field. Sampling was performed on four occasions: one day before and 3, 7, and 14 days after spraying. The treatments included matrine (at concentrations of 1.5 and 2ml/L), deltamethrin (0.3ml/L), fenitrothion (1ml/L), and a control treatment (water). The potential effects of the insecticides were examined on the larvae of natural enemies, including the seven-spotted ladybird, flower fly, and green lacewing. Tehran and Ardabil provinces had low flower fly and green lacewing populations across all treatments, including control. However, the ladybird population was sufficient for evaluation. Therefore, the effects of the insecticides on ladybirds were investigated in these provinces.

The reduction in the population of seven-spotted ladybirds in Ardabil caused by the insecticides was insignificant on days 3 and 7 and significant on day 14. Deltamethrin caused the most negative effect on days 3 and 7, while matrine 2ml/L had the most negative effect on day 14. Deltamethrin consistently caused the largest ladybird population decline in Tehran, with a significant difference from other treatments on all days except day 3. Fenitrothion exhibited the least adverse effect throughout the experiment. Golestan had the healthiest natural enemy populations. In this province, a suitable population of seven-spotted ladybirds, flower flies, and green lacewings was observed. The study confirmed insecticide-induced declines in these populations, with deltamethrin causing the most significant reductions for ladybirds and flower flies, while fenitrothion had the least impact. All insecticides severely reduced green lacewing populations. Based on the results of the 7th day, the reduction of the population of seven-spotted ladybirds in different provinces caused by matrine 1.5 and 2ml/L, fenitrothion, and deltamethrin was 31.04% – 57.91%, 54.19% – 77.58%, 25.01% – 70.16% and 72.02% – 89.35%, respectively. In addition, population reduction caused by matrine 1.5 and 2 ml/L, fenitrothion, and deltamethrin was 31.61%, 67.01%, 24.58%, and 79.06% for flower fly, and 73.24%, 82.79%, 73.24% and 95.94% for green lacewing, respectively. In all cases, the reduction caused by matrine 2ml/L was higher than matrine 1.5ml/L. On day 7, most insecticides were slightly harmful to seven-spotted ladybirds in all provinces except Tehran and Golestan, where fenitrothion was harmless and deltamartin moderately harmful. On this day, matrine, fenitrothion, and deltamethrin were slightly harmful, harmless, and moderately harmful to flower flies, respectively. Moreover, matrine 1.5ml/L and fenitrothion were slightly harmful to green lacewing, while matrine 2ml/L and deltamethrin were moderately harmful.

Deltamethrin consistently exhibited the most pronounced adverse effects across all treatments and natural enemy populations, while fenitrothion had the least severe impact. Green lacewing populations displayed the highest insecticide sensitivity among the studied natural enemies. Based on the results, the effect of insecticides on non-target beneficial organisms was essential when developing integrated pest management (IPM) strategies. Avoiding the application of insecticides, particularly deltamethrin, during peak natural enemy populations was crucial to minimize unintended ecological consequences and promote a balanced ecosystem within wheat fields.

Agriolimax agrestis is one of the important pests of greenhouse ornamental plants in Iran and the world, especially in the northern provinces which cause a relatively large amount of damage to them in greenhouses every year. Chemical molluscicide, metaldehyde, is considered one of the most important compounds widely used to control the slug. The compound may cause many concerns for human health and other organisms (aquatic, birds, livestock, etc.) by entering the environment. Therefore, replacing high-risk chemical molluscicides with environmentally friendly and safe compounds can reduce the side effects of pesticides and the occurrence of resistance in this pest to the molluscicides. This research evaluated the effectiveness of Tobalin® as mineral compound 5% SC containing copper hydroxide in reducing the damage of A. agrestis slug.

In the laboratory conditions, the effect of Tobalin® (4 ml/L) on slug feeding was investigated by choice and non-choice methods. For the study, the surface of the leaves was measured before the start of the experiment using Image J software (ij153-win-java8), and the eaten surface by slugs was calculated after seven days.In the repellency test, treatments included: (1) untreated pot and plant, placed on a copper hydroxide-treated substrate (plastic cafeteria tray); (2) sides of pot sprayed with copper hydroxide but plant foliage and substrate not treated; (3) plant foliage and pot treated with copper hydroxide and placed on untreated substrate; (4) untreated plant and pot (water spray only) placed on untreated substrate (untreated control). 60 slugs, each of which was 0.7 to 1 g in mass, were released into the center of the screenhouse, and each pot containing a plant was examined for the presence of slugs. The cumulative number of slugs observed on each plant and pot during 21 d of observation was totaled. The total number of leaves damaged by the slugs was determined at this time. In greenhouse conditions, spraying of concentration of 4 ml/L of Tobalin® with the chemical molluscicide metaldehyde (2.5g/m2) and the mineral molluscicide Ferricol® (5g/m2) as bait and control treatment (water) on ornamental plants Spathiphyllum wallisii was carried out in the greenhouses of Mazandaran and Alborz provinces. The experiment was done in a completely randomized design in 10 square meter plots with four repetitions of 2.5 square meters. Slugs (0.7 to 1 g weight) were released in equal numbers (40 pieces) in each plot on S. wallisii bushes. Then, the damage caused to the plant by feeding slugs was determined on 7, 14, and 21 days after applying the treatments.

According to the results, in choice and non-choice tests, slugs fed on untreated leaves (12.4 and 17.3 square centimeters, respectively) more than Tobalin® treated leaves (6.3 and 7.1 square centimeters, respectively). In the repellency test, the mean number of slugs counted in the plant + pot treatment during 21 days was 0.4 and 0.3, respectively, in Mazandaran and Alborz provinces, which was less than other treatments. Also, the percentage of damaged leaves in the pot plus plant treatment was 20.4% and 22.5% in Mazandaran and Alborz provinces, respectively, compared with control, 73% and 75.25%. In the greenhouse, on the 21st day after the treatment with Tobalin® (4 ml/L), the damage to the plant in Mazandaran and Alborz provinces was 27.2 and 25%, respectively, which were grouped without statistically significant difference with the treatment of bait metaldehyde with the amount of damage, 15.7 and 15% respectively. Considering that from the 7th to the 21st days of the experiment, the amount of damage in Tobalin® treatment is increasing and this compound is not lethal to slugs, repeating the foliar spraying after two to three weeks is necessary for the continuation of its anti-feeding and repelling effect.

Mineral compound Tobalin® can be used to deter Agriolimax agrestis. It is worth mentioning that there is no need to use bait when using Tobalin® and this compound can be used as a substitute for chemical pesticides in the integrated management of slugs on ornamental plants in greenhouses.