Plant Protection
Year:2017 | Volume:40 | Issue:3 |Papers Count:8

Two-spotted spider mite, Tetranychus urticae Koch, is one of the most important polyphagous pests because of severe damage, high population growth rates and ability of making resistance to pesticides. In this research, contact toxicity of concentrations of Sirinol, Tondexir and their combination, and also repellency effect of Palizin were studied in order to find a proper substitute for synthetic acaricide and to omit their pollutant effects on the environment.The experiments were performed at 25±2 C, 60±5% relative humidity and 16: 8 (L: D) on adult females by adopting a leaf dipping method. Sirinol at 5700 ppm and Tondexir at 5300 ppm concentrations created the highest mortality. LC50 and LC90 values of Sirinol and Tondexir were, 1775.908, 16772.6 and 2130.914, 11975.205 ppm in 24 hours and 463.228, 5985.136 and 907.931, 6052.447 ppm in 48 hours, respectively. Combined application of Sirinol and Tondexir (LC25) caused 66.66% mortality at 24 hours which was higher than mortality caused by their separate application. Palizin was ineffective at 250 ppm concentration, but at 500, 1000, 2000 and 4000 ppm showed repellency activity. According to these results, the combinations of tondexir and sirinol and repellency effect of palizin were high and can be suggested in the integrated pest management programs of this mite.

In this research, the influence of intercropping systems (including three, six and nine rows of green bean, Phaseolous vulgaris L. with alternate three rows of clover, Trifolium resupinatum L.) and monoculture of green bean on biodiversity of the onion thrips, Thrips tabaci Lindeman and the proportion of predators/prey density was studied in an experimental field in Ardabil during 2015 and 2016 years.21 species of onion thrips predator were collected and identified among which the predator speciesAeolothrips intermedius Bagnalland and Orius niger (Wolff) had the highest relative abundance in each of cropping systems. The Shannon diversity index (H) was significantly greater in each of the three intercrops than in green bean monoculture. The values of Morisita–Horn index (CMH) between green bean monoculture and each of the three intercrops (CMH £ 0.85) were lower in comparison with the values of this index among the three intercrops (CMH ³ 0.94). In two years, the proportion of predators/prey and the density of the onion thrips predators especially two dominant species A. intermedius andO. niger in each of the three intercrops were significantly higher than in green bean monoculture. Therefore, it can be concluded that strip-intercropping of green bean with clover caused higher biodiversity of the onion thrips predators and reduced the density of T. tabaci.Application of the strip-intercropping systems in the green bean fields as one of the important components in the integrated management of the onion thrips is recommended.

Peach powdery mildew (Podosphaera pannosa) is one of the most economically destructive diseases of peach all over the world including Iran. In order to evaluate 25 genotypes of peaches reaction against powdery mildew, an experiment was conducted in randomized complete block design with three replications during 2014-2015 in Agriculture and Natural Resources Research Station in Meshginshahr.The research was conducted in two conditions of natural infection and artificial inoculation. Genotypes included Robin, Red heven, Early red, Spring crest, Vesevio, Red top, J.H. Hale, Shasta, Early glo, Amesdn, Loring, Spring time, Velvet, Sudanell, Sundance, Anjiri, Haj kazemi, Paeizeh, Elberta, Baby gold7, Dixi red, Red skin, Sabz-e-Mashhad, Sun crest and July Elberta. Evaluation of different genotypes of peaches reaction to powdery mildew was conducted as follows: 0: immune, 1: very resistant 2: resistant 3: medium resistant 4: sensitive and 5: very sensitive. The results of two year evaluation showed that there were significant differences between the degrees of resistance among the treatments.Comparison of the means showed that the genotypes J.H. Hale, Anjiri, Loring, Red top, Red heven and Early glo were veryresistant; Vesevio, Elberta, Spring crest, Velvet, Shasta, Early red, Red skin and July Elberta were resistant; Baby gold7, Sundance, Amesdn, Haj kazemi, Spring time, Dixi red and Robin weremedium resistant; Sun crest and Sudanell in sensitive and Sabz-e-Mashhad and Paeizeh were very sensitive genotypes. The results of the current study could be used in management of peach powdery mildew.

The biodiversity of Collembola was evaluated in three different ecosystems: field crop, oak forest and grassland in two cities (Paveh and Sare pol-e-Zahab) monthly from May 2012 to May 2014. In each site, a soil sample was collected with a diameter of 10 cm and 13 cm depth. Species richness, biodiversity and the indices of similarity were calculated usingα, β, γ, Shannon-Wiener, and Jaccard-Sorenson indices. The results showed that the biodiversity and species richness of forest was higher than the field crop and grassland in two different cities. In Paveh, the species richness of the field crop was higher than the grassland.However, there was no significant difference between the field crop and grassland in Sare pol-e-Zahab city, unexpectedly. Comparison between the similar ecosystems between the two cities showed that the biodiversity of Paveh's forest was higher than the forest of Sare pol-e-Zahab. By contrast, the biodiversity in Sare pol-e-zahab's grassland was higher than that of Paveh and there was no significant difference between the field crop in the two different cities. Comparison of Shanon- gamma index between the two cities showed that biodiversity of Paveh was higher than that of Sare pol-e-Zahab. Comparison of the different ecosystems showed that the field crop and grassland had more similarity compared to the forest in the two cities.

In this research, the effect of plant pesticides tondexir (Tondexir®) and chemical acaricides fenpyroximate (OrtusÒ) was investigated on the egg and an adult of two-spotted spider miteTetranychus urticae and its natural enemies Phytoseiulus persimilis in lab and field conditions. To evaluate the effect of field recommended concentrations (2000 ppm tondexir and 700 ppm fenpyroximate) an experiment was also conducted with three treatments and four replications in a randomized complete block design under field conditions. The numbers of T. urticae and P. persimilis (egg and adult) on leaf samples were counted before treatment and 3, 7, 14 and 21 days after treatment. The LC50 values of tondexir and fenpyroximate on the egg and the adult of T. urticae were 661.01, 396.1 and 379.3, 291.6 ppm 72 h after treatment respectively. The egg and adult of P.persimiliswere less susceptible compare to T. urticae and fenpyroximate toxicity was higher than the tondexir for this predatory mite. The field bioassay results showed tondexir to have longer persistency effect than fenpyroximate. According to IOBC standards, 21 days after treatment, tondexir and fenpyroximate were categorized as moderately toxic and very toxic for both egg and adult of predatory mite, respectively. The overall results showed that tondexir caused high mortality on the egg and adult of spider mite and its toxicity was less than fenpyroximate to predatory mite.

Fertilizers are commonly used to enhance the quality and quantity of agricultural products, but they can also improve the tolerance or resistance level of plants against parasitic nematodes.The current study was performed in two separate experiments. In the first experiment, the effect of Nano-K and potassium sulphate fertilizers as well as salicylic acid (SA) was assessed on the growth of nematode-free tomato plants. In the second experiment, the effect of mentioned fertilizers and SA was investigated on plant growth and nematode control in a completely randomized factorial design. The recommended dose of potassium sulphate was mixed with the soil of one kg pot a week prior to planting tomato seeds. Nano-K fertilizer was sprayed on tomato seedlings three days before and two weeks after-nematode inoculation.SA was sprayed 24 h before- and one week after-nematode inoculation. Tomato seedlings were inoculated with five eggs and second stage juveniles ofMeloidogyne javanica per g soil at the four-leaf stage. The pots were kept in a greenhouse for eight weeks. The highest growth of nematode-free tomato plants was seen in the pots that were sprayed with Nano-K or SA. In the nematode-infected plants, the effect of SA was more significant than the effect of application or kind of potassium fertilizers that were used. The highest plant growth and lowest nematode reproduction occurred when the plants were sprayed with SA and Nano-K.When SA was not sprayed, application of potassium sulphate did not result in the best plant growth, but it was more effective in reducing the population density of M. javanica.

Stem borer moth, Sesamia cretica Lederer, causes major damage on sugarcane. Sex Pheromone ofS. cretica was synthesized in the chemical laboratory of Iranian Research Institute of Plant Protection. Efficacy of the synthesized pheromone with 3 types imported pheromone ofS. cretica from Russell, Econex & Silvanderson companies were tested at the fields of Sugar cane Agro-Industrial Company of Ahvaz during 2014. Also, attractiveness of the synthesized pheromone was investigated with funnel and delta traps.The results showed significant differences among treatments (p<0.01). The synthetic pheromone with doses of 0.5, 1 and 2 mg had more attractant (5±0.91, 2.75±0.45 and 3.75±0.85 mean±SE, respectively) in comparison with the imported pheromones that had no moth capture. Analysis of the imported pheromones by mass spectroscopy devices indicated these pheromones contain only two molecules including (Z) -9-tetradecen-1-ol and (Z) -9-tetradecen-1-ylacetate. None of the imported pheromones had third molecule (Z) -11-hexadecen-1-ol, and for this reason they had no attraction for S. cretica in the field experiments. Funnel traps with doses of 1 and 2 mg had the most trapping (12.25±2.68 and 11.25±2.80, respectively). Delta trap treatments with doses of 1and 2 mg had less capture (0.00±0.00 and 0.25±0.25). Therefore, we can conclude that proper formulation forS. cretica sex pheromone with three molecules and a funnel trap is the most suitable shape for trappingS. cretica.