نشریه گیاه پزشکی کاربردی
سال سوم شماره 3 (پیاپی 11، پاییز 1393)

Damping off of cucumber caused by Pythium aphanidermatum (Edson) Fitzp. Usually appears when climatic conditions especially high humidity and favorable temperature are available and also in the lack of crop rotation. In the present study efficacy of some fungicides inctuding Propamocarb hydrochloride (Proplant722sl®), Metalaxyl (Ridomyl GR 5 %®) and Bordeaux Fix (SC 18 %®) on control of cucumber damping off was investigated in nursery and greenhouse. The effect of Propamocorb hydrochloride with dosages 0.75, 1 and 1.25 ml/1000 was compared whit Metalaxyl G2.5g/m2, Bordeaux Fix Sc5 mg/1000 and control (without fungicide) using a completely randomized designe.Simple and combined analysis of variance was carried out by SAS soft ware. The results showed that the percentages of cucumber seeding’s damping off in nursery and greenhouse were significantly different among the fungicides with apphed dosages. In nursery, Propamocarb hydrochloride 1ml/1000 with 7.62% damping off had the highest effect on disease control and Bordeaux Fix with 41.50% damping off had the lowest effect compared to the other fungicides and control treatments. In greenhouse, the highest and lowest percentages of damping off (45.00% and 3.75%, respectively) were recorded in propamocarb hydrochloride 0.75 m/1000 and metalaxyl 2.5g/m2 treatments.

Southern corn leaf blight caused by Bipolaris  maydis is one of the most important diseases of maize and causes major losses in quality and quantity of yield in corn. The most effective way for control of disease is use of resistant cultivars. To evaluate the reaction of maize genotypes to the disease on experiment was arranged as split plot in RCBD with three replications and 15 genotypes (6 hybrids, 9 lines and a susceptible check) at Karaj and Sari stations. The mixture of five aggressive isolates were used for artificial inoculation at two growth stages of plant (spraying with spore suspension at 4-6 leaf stage and Bazooka technique with sorghum kernels infected to B. maydis at 6-8 leaf stage). Genotypes were evaluated based on disease severity percentage on leaves two weeks after flowering time. The results of combined variance analysis showed that there was a significant difference at 1% probability level among corn genotypes. Based on the results, three lines K1263/17, K615/1, S61 and two hybrids KSC 201 and KSC 301were susceptible, four lines K1263/1, KE75039, K1264/5-1, K1728/8 and hybrid KSC 260 were moderately susceptible, two lines OH43/1-43, KE72012/12 and two hybrids KSC 250 and KSC 340 were moderately resistant. Hybrid KSC 400 was the only genotype that induced chlorotic lesion on lower leaves of all genotypes and was assessed as resistant. Due to favorable climatic conditions and high disease incidence in Sari station percentage of susceptible genotypes in Sari (53.33%) was higher than that Karaj (26.69%).

Root and basal rot caused by Fusarium oxysporum f.sp. cepae is one of the most important diseases of onions that causes significant economic losses in onions fields. To recognize the genetic diversity and relationship among isolates of the pathogen, 30 isolates which had been collected from Isfahan, Kerman, Ardebil and Fars provinces, Iran were studies in 2012. Pathogenicity diversity of the isolates was investigated by inoculation of all isolates on three cultivars of onion named Sefid Kashan, Sefid Ahvaz and Ghermez Azarshahr in greenhouse. Genetic diversity of the isolates was also investigated by RAPD and PCR-RFLP techniques using ITS1 / ITS4 primers. Molecular data were analyzed by NTSYS-pc software and isolates were then classified using Jaccard coefficient and UPGMA simulated methods. In pathogenicity experiment, onion bulbs infected with isolates were planted in pots and maintained in greenhouse with 25 ˚C, 70% RH and 12h light. The experiment was carried out in completely randomized design with five replications and disease severity for each isolate were assessed three weeks after planting. The results showed that disease severity of isolates was significantly different at 1% level of probability in different onion cultivars but no significant relationship was detected in pathogenicity variation and genetic diversity among the isolates.

Phytophthora root and crown rot is one the most important diseases of apple in Iran and worldwide. This research was performed first to recover oomycete species from infected apple roots and crowns, second, establish a reliable method for inoculation of apple rootstocks and third, evaluate disease resistance of some apple rootstocks in tissue culture media. Different infected samples were collected from the Horticultural Research Stations of Seed and Plant Improvement Institute in Karaj. Three Phytophthora cactorum isolates in addition to one Pythium sp. isolate were recovered out of 20 samples using semi selective media containing Carbendazim, Pimaricine and Rifampicin, 10 mg per liter each. Pathogenicity test was carried out on unripe pear fruits. For disease resistance evaluation experiments, five apple hybrid progenies (H1-H5) obtained through crossing between local genotype Morabbai mashhad and M9 plus the parents, M26, MM106 rootstocks and local genotype Azayesh were assessed to Phytophthora in tissue culture jars. Plant materials were micropropagated on QL media and inoculated with P. cactorum. The pathogen was amplified on the wheat grains so that the pathogen incited necrosis on the shoots inside the jars. The extent of necrosis was recorded after 18 days. Hybrid H5 was assessed as the most sensitive genotype to P. cactorum while hybrid H1 showed high level of resistance reaction.

Phytophthora root and crown rot is one of the main reasons for stone fruit trees decline that is sometimes called as short life of stonefruits. This study was initiated to establish an accurate and reliable method to inoculate plum genotypes and screening resistant genotypes to the disease. Infected plant tissues were collected from Meshkindasht and Kamalshahr Horticultural Research Stations of Seed and Plant Improvement Institute located in Karaj. Using semi-selective media containing Carbendazim, Pimaricine and Rifampicin, 10 ppm each, two isolates of Phytophthora were obtained from apricot and almond. They were identified as P. cactorum according to physiological and morphological characteristics. Resistance of genotypes to Phytophthora was evaluated using ST107 isolate of P. cactorum isolated from apricot. The plant materials including eight promising genotypes of plum and greengage were propagated on MS tissue culture media amended with Carbendazim successfully, and the pathogen was reproduced on sterilized wheat grains, simultaneously. A single infected grain was located on base of each shoot and the necrosis was recorded after 10 days incubation at 24°C in dark. A four parts scale was used to assess the response of the genotypes. All genotypes were infected with P. cactorum isolate with different severities. Genotypes 3547, 3554, 3553, 3542, 3538, 3528 and 3515 showed more than 70 percent of necrosis extension index. Genotype 3512 showed moderately resistant reaction with less than 50 percent of necrosis extension index.

A faunistic study of leaf beetles (Chrysomelidae) was done in Tehran, Alborz and Qazvin provinces of Iran, during 2012 to 2015. In this study, eight species belonging to four genera were identified, of which Clytra laeviuscula (Ratzeburg, 1837) is new record for Iranian Clytrini. In addition, three species are new to Qazvine province, two species are new to Tehran province and one species is new to Alborz province.