Plant Protection
Year:2016 | Volume:39 | Issue:1|Papers Count:8

In this study, response of 18 bread wheat cultivars were evaluated in interaction with five Mycosphaerella graminicola isolates from five provinces in seedling stage. In this experiment, the seeds were treated by 0, 0.75 and 1 mM concentrations of salicylic acid. According to the analysis of variance, significant difference (p<0.01) was observed between cultivars, isolates an SA concentration levels. Also consistent with the results of the analysis of variance, interaction between cultivar-isolate, cultivar-concentration and isolate-concentration had significant difference, which indicates that there are specific interactions between these interactivities. Seventy-eight percent of cultivars were susceptible in interaction with all of the isolates and eleven isolate-specific resistances were observed among other cultivars. Marvdasht with three isolate-specific resistance were the most resistant cultivars in this study and after Marvdasht, Hirmand and Toos, with three isolate-specific resistance but high levels of pycnidia coverage percentage compared with Marvdasht had the next ranks. Based on the virulence, all isolates fall into four different groups and S1 were virulent on most cultivares, but none of the isolates were avirulent on all cultivars. Comparition of pycnidia coverage average represents a significant reduction in the area of pycnidia coverage in 1mM concentration of SA compared to the zero and 0.75 mM levels. The 1mM concentration had greatest impact on symptoms reduction.

Late blight is the most important disease of potato crop throughout the world and in northwest of Iran, which can destroy the whole crop in epidemic years. According to the Department of Agriculture in Ardabil province, the late blight reached an epidemic level in 1997 in Ardabil plain and resulted in major damage to the crop. Climatic factors including temperature, relative humidity and rainfall play the major role in developing and spreading of this disease. In this research the effects of temperature, rainfall and relative humidity on the incidence of the late blight was investigated in Ardabil plain. Daily, monthly and yearly weather data of Ardabil climatic station were obtained for the period of 1992 to 2002. Data were grouped and analysed using graphical and statistical methods. Initially, variance analysis was conducted using nested method between study years and within the months of years. Then study years were grouped using UPGMA analysis method. It was found that: there were significant correlations between climatic factors, particularly temperature and rainfall with the incidence of the late blight. Study years grouping using climatic factors in the incidence period of late blight could discriminate the year 1997 from the rest of the years. Moreover, it was recognized that, when an effective rainfall (about 30 mm) occurs in the growing season and mean daily temperature range is about 20oC for 10 consecutive days, there is a possibility of occurrence and spreading of the disease, and preventive measures must be taken.

To investigate the effect of root-knot nematode M. incognita race2 on tomato defense enzyme production process, an experiment was conducted under greenhouse conditions. The experiment was carried out in a completely randomized split split plot design with two susceptible (Falat Y) and tolerant (Gina VF) tomatoe varieties with four nematode population levels of 0 (control), 500, 1000 and 2000, the number of larvae of second stage with four different sampling times (0 (control), 3, 5 and 7 days after inoculation) and with four replications. In this experiment, after sampling, purification, identification and propagation of nematode species and race of nematodes were determined. With nematode purified amplification on the Rutgers cultivar tomato inoculum was obtained. The four-leaf stages were inoculated population in levels and the time mentioned of the enzyme was measured. The results showed that increasing levels of nematode population affected plant biochemical activities and the total protein content decreased. The activity of catalase, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase involved in the defense reaction of host plant increased. The highest rates were observed in the catalase enzyme and in the tolerant variety. In the presence of nematode stress, plant activated its defense mechanism that has enabled it to increase its enzymatic activity which was at its maximum value 5 days after inoculation.

In order to identify the plant parasitic nematodes of potato field in Lorestan province, 70 soil and root samples were collected from different regions of Lorestan province, during years 2013- 2014. After extraction and preparation of permanent microscope slides, by using of light microscope, equipped with digital camera. According to morphologic and morphometric characters and valid key nematodes species studied and identified, and their relative abundance determined. In this research 28 nematode species belonging to 19 genera of suborder Tylenchina including Aphelenchoides graminis, Aphelenchus avenae, Boleodorus thylactus, Ditylenchus medicaginis, D. dipsaci, D. myceliophagus, Ektaphelenchoides sp., Filenchus andrassy, F. hamatus, Geocenamus rugosus, Helicotylenchus digonicus, H. tunisiensis, H. vulgaris, Irantylenchus vicinus, Merlinius brevidens, M. nanus, M. microdorus, Mesocriconema sp., Neopsilenchus magnidens, Paraphelenchus amblyurus, Paratylenchus sp, Pratylenchoides ritteri, Pratylenchus neglectus, P. thornei,, Psilenchus hilarulus, Rotylenchus cypriensis, Tylenchorhynchus dubius, Zygotylenchus quevaria were identified. The Aphelenchoides graminis and male of Pratylenchus neglectus and Filenchus andrassy are new recordes for Iran so the descriptions of this species and male and female of Pratylenchus thornei are presented in this paper. The characterstics of Ektaphelenchoides sp. were different from the described species of this genus and its identification is going on The results showed that Pratylenchus neglectus, Ditylenchus medicaginis and Pratylenchus neglectus with 78.57, 71.42 and 57.14PFP, respectively, have the highest PFP in potatoes field of Lorestan province.

Nowadays, the use of nanoencapsulation technology of pesticides causes increase in efficiency and controlled release of these substances. In this study, the antifeedant and repellent activities of nanoencapsulated formulation (NEF) of wormwood sagebrush Artemisia sieberi Besser essential oil wereinvestigated against the elm leaf beetle Xanthogaleruca luteola (Muller). The experiments were conducted at 25±2oC, 65±5% RH and a photoperiod of 16:8 h (L: D). NEF decreased the nutritional indices significantly compared to non-formulated oil. NEF at a concentration of 4000 ppm, reduced efficacy of conversion of ingested food and efficacy of conversion of digested food in larvae, twice lower compared to pure essential oil. The repellency of non-formulated essential oil at a concentration of 8000 ppm reached it’s highest level after 6 h exposure, while the repellency of NEF increased over time and reached to 100% after 24 h and continued for 72 h. Therefore, further investigations are necessary to consider the NEF made by the A. sieberi essential oil as an effective toxicant against the elm leaf beetle.

The cotton mealybug, Phenacoccus solenopsis Tinsley has caused serious damage to Chine rose Hibiscus rosa-sinensis recently. Biological characteristics and life table parameters of Nephus arcuatus Kapur feeding on P. solenopsis was studied at 25, 30 and 35°C under laboratory conditions. Mean developmental time of female and male on three above mentioned temperatures were 28.75, 18.85, 14.68 and 21.73, 18.85, 14.40 days, respectively. Mean preimaginal mortality were 36.33, 33.4 and 49.33 %, respectively. On the same three temperatures, mean female adult longevity, mean daily eggs, mean total egg and intrinsic rate of increase were 84.76, 99.3 and 61.64 days, 7.79, 6.71 and 3.72 eggs, 384.5, 585.3 and 126.00 eggs and 0.09923, 0.13519 and 0.15064, respectively. Based on the results obtained, 35oC was the optimal temperature for growth and reproduction of N.arcuatus. Based on the results obtained, 35oC was the optimal temperature for growth and reproduction of N.arcuatus. Based on the results obtained, 35oC was the optimal temperature for growth and reproduction of N. arcuatus.

External parasitoid wasp Bracon hebetor Say larvae of some pests stored dates. In this study, the change in population growth in four steps bat nuts Ephestia kuehniella Zeller affected parasitoid B. hebetor for 6 months in vitro was paid. Two populations in this experiment repeated 3 glass boxes. First population included 500 pesticides and 50 larvae with parasitoid sex ratio and the second population contains only 500 larvae are pests. Curve changes in population activity were observed tow peaks density in the first period egg stage, larva, pupa and insect full 11 weeks, respectively, 6, 8 and 11 weeks during the second 22, 21, 20 and 22 was observed. During the 24 week ware housing always pest population growth in four stages, assembly conditions (presence of parasitoid population) to less than control treatment (no parasitoid population), respectively, so that the maximum reduction equal to 5.25, 5.36, 4.2 and 4.78 respectively in the four steps were growing pest control suggests that high performance in parasitized by the wasp larvae bat nuts and ultimately control it