نشریه آفت کش ها در علوم گیاه پزشکی
سال ششم شماره 2 (پاییز و زمستان 1398)

Nowadays, the pollution in aquatic ecosystems caused by the application of pesticides has become a serious problem. To evaluate the phytotoxicity of ten herbicides used in wheat and barley fields by duckweed (L. minor) test, a dose-response experiment was carried out in completely randomized design with four replications. The treatments consisted of eight different concentrations of various active ingredients of herbicides including clodinafop-propargyl, pinoxaden, pinoxaden + clodinafop-propargyl, diclofop- methyl, fenoxaprop-p-ethyl, mesosulfuron-methyl + iodosulfuron-methyl sodium, metsulfuron-methyl+ sulfosulfuron, 2,4-D and bromoxynil + MCPA with herbicide-free control treatment. Toxicity assessment index was based on inhibition of the relative leaf surface growth rates (RGR) of the plants after seven days. The EC50 values which were derived by fitting the log-logistic curves, showed that bromoxynil + MCPA with EC50 equal to 0.51 microgram/l had the highest effect in reduction of the relative leaf surface growth rate of Lemna compared with other herbicides. This high toxicity probably is attributed to its physicochemical properties and rapid uptake by the plant cells. 2,4-D with EC50 equal to 87.97 µg/l showed the lowest toxicity on Lemna. The phytotoxicity of the nine herbicides tested could be ranked as follows: Bromoxynil +MCPA > Mesosulfuron-methyl + iodosulfuron-methyl sodium > Pinoxaden > Pinoxaden + Clodinafop-propargyl > Diclofop- methyl > Metsulfuron-methyl+ sulfosulfuron > Clodinafop-propargyl > Fenoxaprop-P-ethyl > 2,4-D.  The information obtained from the results of the present study can be useful for adopting the necessary criteria for aquatic ecosystem management.

Apple powdery mildew is one of the most important and common fungal disease of apple trees that reduces the quantity and quality of this fruit. The efficacy of Triflumizole (Trifmin® EC 15%) as a target fungicide in controlling apple powdery mildew was evaluated in a randomized complete block design with seven treatments including:  0.5/1000, 0.75/1000, 1/1000 and 1.25/1000 of Triflumizole, 0.3/1000 of Trifloxystrobin + Tebuconazole (Nativo® WG 75%) as control fungicide, control with water spraying and control with no spraying in four replications. The field trials were undertaken in three provinces of Isfahan (Semirom), Kohgiloyeh Va Boyerahmad (Yasuj) and eastern Azerbaijan (Tabriz). Three commercial orchards of susceptible cultivar Golden delicious (seedling rootstock) with a history of infection were selected. Sprayings were done three times (at swelling flower buds stage), at the end of flowering time and two weeks later. The sampling of leaves was carried out at the end of the summer. The evaluation of experimental plots was performed in the second half of September and at the same time with the completion of the apical buds, by random selection of 50 leaves from 10 branches and by calculating the percentage of occurrence and the percentage of disease severity based on Spencer's scales. Data were analyzed for variance and mean comparison with SAS program through Duncan Multiple Test at 5% probability level. Comparison of Mean showed that concentrations of 1/1000 and 1.25/1000 of Triflumizole and 0.3/1000 of Trifloxystrobin + Tebuconazole with 78%-93% and 79%-95% reduction in incidence and severity of the disease compared with the control with no foliar spraying in one group respectively Therefore based on the results Triflumizole with the concentration of 1/1000 is recommended for the management of apple powdery mildew.

Presenting an effective classification procedure that discriminates between unexposed and exposed plant samples with pesticide, can be very important and efficient to increase quality control in agricultural products and food safety. The proposed method shows a pattern for discriminating between rice plant without contamination and those treated with diazinon. The aim of this study was to investigate the metabolic changes of shiroodi cultivar rice plant (the most common cultivar in Iran) in response to diazinon and to evaluate the dynamic changes in the concentration levels of metabolites over time. For this purpose, after treating the rice plant with diazinon, un-volatile metabolites were derivatized to make volatile and analyzable compounds with gas chromatography, and the metabolite profile was investigated using GC-MS. Using Classification and Regression Tree (CART), the metabolites that showed the most changes under diazinon stress were identified. For the first time, CART was used to model and predict the metabolic changes of control and under diazinon stress rice plant. The results of the analysis showed that, the most intensive changes were related to amino acids particularly phenylalanine and proline. The results obtained, also, show that CART   can be a very powerful tool for discriminating between exposed and un-exposed plants.

Termites are among the pests that cause damage to crops, forests, stored food and home wooden appliances. The use of chemical insecticides is the most common  and effective method to control  termites  In this research three insecticides from three different groups were evaluated to determine the optimal dose as a protective barrier. The treatments included: fipronil (SC 2%) 0.5% and 1%, chlorpyrifos (EC 40.8%) 1%, lambda cyhalothrin (SC 5%) 0.5% and 1%, 50 g of fipronil (G 0.2%) and control (water). The experiment was conducted in Hormozgan province. One meter of each palm canopy was considered as a plot and 20 liters of insecticide solution was poured around each tree. In order to evaluate, two tracking traps were installed around each tree, so that one trap was installed inside and the other outside the plot. Termite control index was determined based on the amount of cardboard eaten in each trap. To determine the duration of the effect of treatments, trapping studies were continued for 6-16 months after treatment. Data were statistically analyzed non-parametrically. The results showed that the outside bait traps were not significantly different from each other in terms of infection. The treatment of Fipronil with granular formulation (with 19 infested traps) was not effective in termite control whereas lambda cyhalothrin 1% had the least termite infested traps (5 infested traps) during 6 months after treatment.

Helicoverpa armigera is one of the key pests of tomato in Iran. To evaluate the efficacy of new insecticide α-cypermethrin + teflubenzuron (Imunit SC 15%) against this pest,  present research was carried out in a Randomized Complete Block Design with five treatments and four replications in three provinces  of Mazandaran, Qazvin and Fars in 2013 -14. The treatments were α-cypermethrin + teflubenzuron with two doses of 250 and 300 ml/ha, indoxacarb (Avant® SC 15%) with the dose of 250 ml/ha, chromafenozide (Matrik® SC 5%) with the dose of 2000 ml/ha and control (spraying water). At each sampling time, 10 plants from the middle of each plot were randomly selected. The number of larvae of tomato fruit worms, the number of healthy and damaged fruits and the number of infected and healthy fruits in each plot were determined and recorded at each harvest. Sampling was done 1 day before and 3, 7, and 14 days after the treatment The results showed that -  7 days after application, indoxacarb (250 ml/ha) and cypermethrin + teflubenzuron (300 ml/ha) with 78.13±6.96 % and 73.89±5.24% efficacy ranked first in the group in Mazandaran province. Indoxacarb (250ml/ha) and cypermethrin + teflubenzuron (300 ml/ha) with 88.71±7.89 % and 83.54±5.74% efficacy ranked first in the group in Ghazvin province. In Fars province indoxacarb (250 ml/ha) and cypermethrin + teflubenzuron (300 ml/ha) with 78.2±1.73 % and 71.40±1.81% efficacy ranked first in the group.  In all these locations, the number of infested fruits in all treatments were significantly different (α=1%) 14 days after treatments.

Tomato leaf miner, Tuta absoluta (Meyrick) is one of the key and dangerous pests of Solanaceae plants in the world, especially in Iran which is controlled by various insecticides. Excessive use of chemical insecticides can quickly lead to pest resistance. The Use of protein-based compounds such as the enzyme Cholesterol oxidase, is a good alternative to chemical insecticides. In this research, the effect of cholesterol oxidase enzyme on the oviposition preference, larval establishment and weight of pupa of Tuta absoluta was investigated. The three tomato cultivars including Newton, Izmir and Ergon were treated with cholesterol oxidase enzyme at concentrations of 0.08, 0.2 and 0.6 mg/L during three phenological stages of 30, 45 and 60 day old plants. This experiment was carried out at 16:8 D: L and 60 ± 10% relative humidity and 25 ± 8 0C under greenhouse conditions. The results showed that by increasing the enzyme concentration, the oviposition, establishment of larva and weight of male and female pupa decreased. The highest amount of oviposition was on the Ergon cultivar at 0.08 mg/L and the lowest was recorded on the Izmir cultivar at the concentration of 0.6 mg/L. The highest establishment of larvae was recorded on Newton and Ergon cultivar at the concentration of 0.08 mg/L and the lowest was recorded on Izmir variety at the concentration of 0.6 mg/L. The results indicated that the cholesterol oxidase enzyme has the ability to control and repel the tomato leaf miner.

Fungicides and biological symbionts are effective tools in integrated management of damping-off disease of cucumber, which is one of s the most important disease of this crop. In this study the efficacy of the commercial product of Pythium oligandrum (Polyversum®) to control cucumber damping-off disease caused by Pythium ultimum was studied. The experiment was carried out in a Completely Randomized Design with 10 treatments and 4 replications   under greenhouse conditions in Tehran and Karaj. Treatments  included 0.2, 0.25, 0.3, 0.35 and 0.4 gL-1  of Polyversum (WP 17.5%) as the target bio-fungicide, 40 g/1000 plants of commercial product of Trichoderma harzianum T-22 (Trianum-P®)  as standard bio-fungicide, PrevicurEnergy 3 mlL-1 and Rosalaxil® 2 gL-1 as standard fungicides. Bio-fungicides were used immediately after planting in Karaj and 48 hours before planting in Tehran, and in both the regions treatments were repeated at two-leaf stage. Mean comparisons revealed that Polyversum® at the rate of 0.2, 0.25, 0.3, 0.35 and 0.4 gL-1  decreased the disease incidence by 25.5, 28.4, 30.6,42.9 and 45.8%  in karaj and 49, 54.6, 62.5, 61.7 and 64.9%  in Tehran s compared with the  inoculated control respectively. In these trials TrianumP® decreased the disease incidence by 32 and 62.5% compared with the inoculated control in Karaj and Tehran respectively. PrevicurEnergy® and Rosalaxil® decreased the disease incidence by 90.2 and 96.8% in Karaj and 79.9 and 88.6% in Tehran trials respectively. This study revealed that the creation of an opportunity for the establishment of the biocontrol agents in the soil could increase their efficacy.