Journal of Applied Research in Plant Protection
Year:2021 | Volume:10 | Issue:1|Papers Count:8

Trichoderma species are important biocontrol agents of plant pathogens. However, potential of Trichoderma species in insect pest management, remain poorly understood. In this study, the effect of T. harzianum TR6 on the life table parameters of black bean aphid, Aphis fabae, was evaluated under glasshouse conditions and compared to control. The Vicia faba and black bean aphid were reared in a growth chamber at 25 ± 2 0 C, %50 ± 5 RH and a photoperiod of 14 L: 10 D hours. Then, five ml of fungal spore suspension (with concentration of 1 × 10 6 -1 ml ) was added into the rhizosphere soil of sown mugs using a sterile syringe. The results obtained in this study revealed that T. harzianum significantly affected the biological properties of black bean aphid in comparison with the control. Treatment with T. harzianum resulted in the highest developmental time (20. 36 days) and the lowest fertility rate in black bean aphid. There was significant differences in terms of inherent rate of population increase (P≤ 0. 5) compared to the control. The highest rate was occurred in control treatment (0. 42 ± 0. 01 day-1 ) and the lowest in treatment with T. harzianum (0. 16 ± 0. 01 day-1 ). The life expectancy of black bean aphids, which were grown on T. harzianum treated soil, was significantly lower than the control. According to the results, it can be concluded that treatment of faba bean plant with T. harzianum can be effective in reducing the population of the aphids of the bean.

This research was carried out to evaluate the effect of insecticide applications and sowing date on the severity of infestation and damage of European corn borrer (ECB) on three maize hybrids. Two separate experiments (with and without insecticide application against ECB) were conducted as a factorial experiment with two factors including sowing date at three levels (25th April, 10th May and 25th May) and hybrids at three levels (SC704, SC705-and SC706) based on randomized complete block design with four replications. The experiments were conducted for two years in Moghan region, Iran. The results showed that the yield of the studied hybrids under insecticide application conditions (13. 28 t/ha) was significantly higher than that under no insecticide application conditions (11. 45 t/ha). This shows that no insecticide application against this pest reduced grain yield by 1830 kg/ha (13. 80%). The results also showed that 25th May sowing date had the highest grain yield with 14. 57 and 12. 98 t/ha in both insecticide application and no insecticide application conditions, respectively. In no insecticide application conditions, SC706 hybrid with 12. 19 t/ha showed significantly higher grain yield than SC704 and SC705 hybrids with 11. 38 and 10. 78 t/ha, respectively. Based on the two-year average, the SC706 hybrid also had the lowest number of holes per stem, tunnel length per plant, percentage of plant infestation and percentage of stalk breakage due to the pest damage. Therefore, the SC706 hybrid is a productive hybrid that is relatively tolerant against ECB.

Rapeseed is a host for a large number of pathogenic and non-pathogenic fungi, including Fusarium species. During 2018– 2020, 40 rapeseed samples showing yellowing, wilting and rootrot symptions were collected from different areas in Khuzestan province, which led to the isolation of 35 Fusarium isolates on potato-dextrose-agar (PDA). Ten isolates were selected based on the shape of the colonies and conidia and identified according to phylogenetic analysis and morphological features. For molecular study, two regions including the internal transcribed spacer nuclear ribosomal DNA region (ITS) and translation elongation factor 1-α gene (TEF1) were amplified and sequenced. These sequences were analyzed by phylogenetic analysis using maximum likelihood and Bayesian inference algorithms. Accordingly, F. acuminatum, F. clavum, F. gracilipes, F. incarnatum and F. tanahbumbuense, and a representative species of the new lineage were identified. To our knowledge, this is the first report of F. acuminatum, F. clavum, F. gracilipes, F. incarnatum and F. tanahbumbuense on rapeseed in Iran. Moreover, F. gracilipes is a new record for the mycobiota of Iran.

The European red mite, Panonychus ulmi is one of the most important pests of apple orchards in some parts of Iran. This study was conducted in order to evaluate the efficiency of Spiromesifen and Cyflumetofen for the control of European red mite in apple orchards of Isfahan, East, West Azarbaijan and Khorasan-e Razavi Provinces of Iran. Towards this aim, two concentrations of Spiromesifen 24% SC (0. 5 and 0. 4 ml/l) and Cyflumetofen 20% SC (1 and 0. 8 ml/l) were compared with Etoxazole 10% SC 0. 4 ml/l, Propargite 57% EC 1 ml/l, Fenpyroximate 0. 5 ml/L, Spriodiclofen 0. 5 ml/l and control (water sprayed). The percentage of efficiency was calculated by the Henderson-Tilton formula. The average number of mites per leaf was counted one day before and 3, 7, 14, 21 and 28 days after spraying. Statistical analysis was conducted using SAS software with randomized complete block design in multiple places. Cyflumetofen was effective on European red mites in apple orchards of the above-mentioned provinces. Spiromesifen was effective; except in Khorasan-e Razavi provinces. Although in this province, its efficacy increased by increasing time after treatment. The knock down effect of these pesticides was significant. After 3 days, Spiromesifen and Cyflumetofen had caused 88– 99% and 58– 99% of mortality respectively. The efficacy of the compound was up to 99% for Spiromesifen and Cyflumetofen after 28 days that indicated the persistence of these pesticides. We recommend the 0. 8 ml/lit dose of Cyflumetofen and 0. 4 ml/lit dose of Spiromesifen for the control of the European red mite in apple orchards.

Bacterial canker caused by Clavibacter michiganensis subsp. michiganensis is one of the most serious and economically important diseases of tomato worldwide, including Iran. Control of this disease is difficult due to seed-borne nature and long term survival of the bacterial agent on seed. A preventive disease management program based on using pathogen-free seeds and resistant cultivars is the best method for the disease control. In this research, effects of thermal treatment (44-64 ° C for 15, 25 and 35 minutes), chemical compounds (Bordeaux, Nordox, Copper oxychloride and Mancozeb at three different doses), and nine antibiotics (Nalidixic Acid, Gentamicin, Doxycycline, Streptomycin, Erythromycin, Cloxacillin, Rifampin, Cefalexin and Furazolidone) were investigated on tomato seeds disinfestation under laboratory conditions. The results showed that thermotherapy is a suitable approach for seed disinfestation as thermal treatment of 56 ° C for 35 minutes eliminated 98% of bacterial infestation without any effect on seed germination. In lower temperature, seed disinfestation was unsuccessful, and treatments of 60 and 64 ° C showed a significant negative effect on seed germination. Treatments with Rifampin, Nalidixic acid, Doxycycline and Gentamicin were effective in the elimination of 100% bacteria on seeds without any negative effect on seed germination. Treating infected seeds with the copper compounds showed that none of them were able to eliminate the bacteria, and significantly reduced seed germination. Overall, the application of the studied antibiotics is the most effective method for tomato seeds disinfestation for research purposes, but heat treatment at 56 ° C for 35 minutes for the practical application is recommended.

Fusarium ear rot disease of maize caused by Fusarium verticillioides is one of the most important maize diseases that causes grain contamination with fumonisin mycotoxin, which is harmful for humans and animals. In order to determine the general and specific combining ability of 10 inbred lines of maize in response of fusarium ear rot disease, a 10×10 Diallel Cross design was used in 2014 and 90 combinations resulted from a two-way crosses of 10 interested inbred lines were evaluated at Golestan Agricultural and Natural Resources Research and Education Center, Agricultural Research Station of Araghi-Mahaleh in 2015. Trait of the disease severity was assessed on a scale of 1-6. Diallel analysis results based on method one and the mixed model B Griffing showed that additive and non-additive effects are effective in controlling of this trait, but the role of dominance is more pronounced. From the investigated lines two C5 and C53 inbred lines showed the highest significant negative combining ability in response to the disease. The highest heterosis amount was observed in two crossings of C7 × B73 and C7 × C5.

In this research, the effect of Bacillus methylotrophicus in biological control of Pectobacterium carotovorum subsp. carotovorum, the causal agent of potato soft rot disease, as well as the effects of silicon and silicon nanoparticles, the two systemic acquired resistance inducer compounds, against both pathogenic and antagonistic bacteria was evaluated in laboratory and glasshouse conditions. In the disc diffusion and well diffusion assays, silicon and silicon nanoparticles did not produce any inhibitory zone around the tested bacteria, but the antagonistic bacterium, B. methylotrophicus, produced an inhibitory zone of growth in the same and chloroform assays with a radius of 9, 8. 5 and 15 millimeters, respectively. Although, silicon nanoparticles slightly reduced populations of both pathogenic and antagonistic bacteria after 6 and 10 hours post culturing in liquid medium, but after 24 hours, the differences between them and control treatment were not significant. Silicon did not inhibit the growth of the tested bacteria in liquid medium. At glasshouse conditions, all treatments of silicon and silicon nanoparticles as well as antagonistic bacterium were significantly increased the fresh and dry root and shoot weight in compare to positive control, but the best result was achieved by combined treatments of silicon or silicon nanoparticles with antagonistic bacterium. All the treatments completely inhibited disease development on potato plants in compare to positive control and no disease symptoms were observed whereas in control treatments all the tubers showed maceration and rotting symptoms and were destroyed.

Pomegranate is one of the economically important products in Iran. In order to identify the fungal agents involved in canker and dieback disease on pomegranate trees, during the different seasons of 2017-2018, samples were taken from pomegranate orchards with these disease symptoms in East Azarbaijan and Golestan provinces. Disease symptoms appeared as leaf chlorosis, dieback, leaf drop, particularly in the upper crown, vascular discoloration, longitudinal cankers on branches and trunk and bark cracking. Disease incidence was rated about 8 percent. A total number of 178 symptomatic wood samples were collected from pomegranate orchards in two provinces. Ultimately, 171 fungal isolates were recovered from symptomatic tissues. Cytospora punicae was determined as the dominant fungal agent with the isolation frequency of 75 percent, based on combination of morphological characteristics and sequence data of ITS region. Koch’ s postulates were fulfilled using the excised shoot method. The results of pathogenicity assay confirmed C. punicae being pathogenic of pomegranate. The results of present study determined C. punicae as the cause of canker and dieback of pomegranate trees in East Azarbaijan and Golestan Provinces. With the identification and determination of the cause of this disease, in future it will be possible to adopt proper disease management strategies.