فصلنامه گیاه پزشکی
سال چهل و سوم شماره 1 (بهار1399)

Background and Objectives Quercus spp. is the most important and most abundant tree species in west of Iran, especially the Zagros region. The Zagros Mountains have been the original habitat for various Quercus species in Iran. Important pests attack Quercus spp. trees and often cause serious damage. Mites are active arthropod species in oak forests and act as pest, decomposer and predator. Mateials and Methods The bisotunnatural preserved area in Kermanshah province is located in height of 1320 meters above sea level. To investigate the fauna of Prostigmatic mites associated with Quercus spp. in bisotunnatural preserved area, samples were taken from different parts of location in 2018 -2019 from the soil and aerial parts of the Quercus spp. forest trees. Specimens were transferred to the laboratory, separated using berlese funnel, clarified in lactic acid and mounted in Hoyer’s liquid. Results In this study in total 12 species and 16 genera belonging to 12 families were identified. The most abundant species was Molothrognathus mehrnejadi (Liang and Zhang, 1997), from Caligonellidae. Identified species are as follows: Anystidae: Anystis baccarum Linnaeus, 1758; Bdellidae: Cyta coerulipes (Duges, 1834); Cunaxidae: Pulaeus glebulentus Den Heyer, 1980; Tydeidae: Lorryia woolleyi (Baker, 1968), Tydeus caudatus (Duges, 1834) sensu Baker, 1970; Ereynetidae: Ereynetoides amplectorus Hunter, 1964; Iolinidae: Pronematus ubiquitus (McGregor, 1932), Pronematus rykei Meyer & Rodrigues, 1966; Erythraeidae: Parerythraeus sp., Abrolophus sp.; Smarididae: Smaris sp., Fessonia sp.; Raphignathidae: Raphignathus sp.; Tetranychidae: Tetranychus urticae Koch, 1836; Tetranychus turkestani (Ugarov and Nikolski), 1937, Eotetranychus frosti (McGregor, 1952); Trombididae:Allothrombium sp.; Cheyletidae: Acaropsellina sollers Kuzin, 1940. Discussion In this study, the collected species Anystis baccarum Linnaeus, 1758, was previously reported by Yazdanpanah and Ostovan (2014) in the oak forests of the Fars Province. The collected species Cyta coerulipes, Smaris sp. and Fessonia sp. were previously reported by Farahmandi (2015) from the oak forests of Yasuj. In addition, Tetranychus urticae, collected in this study, was previously reported by Niyazi (2017) on oak trees in Ilam province and Amini et al. (2016) from oak in Marivan city. In this study nine species and four genera were collected and reported, which have not been reported previously from oak which include:   Pulaeus glebulentus Den Heyer, 1980, Lorryia woolleyi (Baker, 1968), Tydeus caudatus (Duges, 1834), Ereynetoides amplectorus Hunter, 1964, Pronematus ubiquitus (McGregor, 1932, Pronematus rykei Meyer & Rodrigues, 1966, Tetranychus turkestani (Ugarov and Nikolski), 1937, Eotetranychus frosti (McGregor, 1952), Acaropsellina sollers  Kuzin, 194,Parerythraeus sp, Abrolophus sp, Raphignatus sp. and Allothrombium sp. A Checklist of reported prostigmatic mites from oak forests of Iran is provided as well. This list included 74 species belonging to 10 genera and 17 families.

Grapevine are important and valuable fruits that is contaminated in different parts of Iran, especially in North Khorasan Province, by the downy mildew of grapevine (Plasmopara viticola) and its yield decreases. Investigating the relationship between the incidence and the severity of the disease is one of the important concepts in the epidemiology of plant diseases. It is easier and faster to measure the incidence of the disease, but the severity of the disease is an important indicator.

In this study, the relationship between the incidence disease and severity disease of downy mildew of grapevine in North Khorasan Province (Bojnourd, Mane and Samalghan, Shirvan and Farooj) during 2018 and 2019. Incidence and severity of disease were recorded weekly in 80 selected vineyards from early April to stop the disease progression.

The incidence of the disease was 10.27% in the first year and 51.64% in the second year. The severity of the disease in the first year was between 1.2 to 6.6% (mean 3.4%) and in the second year it was between 6.4 to 44.6% (mean 25.82%). Investigation of the relationship between incidence and severity of disease using four statistical models (power, linear, quadratic, complementary logarithmic logarithm) power model was able to express this relationship in 31 vineyards more accurately. In 24 vineyards the incidence and severity of the disease were well fitted to the data by linear model.

Final models were evaluated based on R2, SEE and Ra2 of regression analysis of raw data. Based on these criteria, final model in Bojnourd as S = (0.534) × I (1.263), in Shirvan as S = (0.684) × I (1.472), in Mane and Samalghan as S = (0.4691)× I-0.01711 and in Farooj as S = (0.3484)×I-0.0078 showed relationship between incidence and severity of disease. This is the first report to evaluate the relationship between the incidence and severity of downy mildew of grapevine in Iran.

Background and Objectives Among biotic stresses, stem (black) rust, caused by Puccinia graminis f. sp. tritici is considered to be the most destructive disease of wheat in some countries and its damage reaches 100% in the years of epidemic on susceptible cultivars. Lack of durable resistance in wheat cultivars is the main reason for the black rust epidemics that can limit wheat production in some parts of the world. Today, it is possible to manage rusts with effective and new fungicides. However, growing resistant cultivars is the most effective, economical, and environmentally safe approach for disease management. Therefore, this study was performed in order to identify potential sources of partial resistance to black rust, which is a stable and non-race specific. Materials and Methods The partial resistance parameters including coefficient of infection (CI), final disease severity (FDS), apparent infection rate (r) and relative area under disease progression curve (rAUDPC) were assessed in a set of twenty six wheat genotypes along with susceptible control (Mixture of McNair and line; CD-90-12) during 2018-2019 cropping year. This study was conducted in field plots at Ardabil Agricultural Research Station (Iran). All genotypes were evaluated under natural infection conditions against race population having virulence to resistance genes; Sr25, Sr5, Sr6, Sr7a, Sr9e, Sr13, Sr23, Sr28, Sr29, Sr30, Sr33, Sr34, Sr37, SrDP2, SrGT, SrWLD, SrH and SrTmp. Seedling reaction was also appraised under greenhouse conditions against TKTTF (two isolates) and TTTTF pathotypes. Results The results showed that genotypes Gascogne, MV17 and Gonbad having low levels of CI, FRS, r and rAUDPC were considered as the group with desirable level of partial resistance. Nine cultivars/lines showed moderate values ​​of resistance parameters and were considered as genotypes with moderate level of partial resistance for stem rust. Six lines had low partial resistance and the rest of the lines were grouped in susceptible group without any partial resistance. Discussion Genotypes Zare, Gascogne, Gonbad, N-91-9, and N-91-15 due to susceptible reaction (at least against to one pathotype) at seedling and moderately resistant to moderately susceptible response at the adult plant stage are likely to have the more number of partial resistance genes. Genotypes with desirable and moderate levels of partial resistance identified from this study can be used to introduce candidate varieties or in wheat breeding programs to stem rust.

Plants produce some compounds for defense against phytophagous insects and mites that may disrupt their endocrine system. Plant phytoecdysteroids and juvenoids are of these compounds that has been isolated and identified from some species. The main function of ecdysteriod is to stimulate development from one molting cycle to the next and compounds like that has been identified in Spinacea oleracea L.. The main function of JH in insect ontogenesis is to inhibit morphogenetic process and compounds like that has been identified in Calendula officinalis L.. The two-spotted spider mite, Tetranychus urticae Koch, is a polyphagous pest worldwide on a variety of host plants which has become resistant to pesticides. Since insect hormone-like compounds in plants, act selectively and are safe for environment they can compete with common pesticides.

A study was carried out to investigate the effect of above mentioned plants on biological parameters of T. urticae in the University of Maragheh. The life table parameters of T. urticae were studied on leaf discs under laboratory conditions (RH 65±5%, 25±1ºC and 16:8 h L:D) with 50 replicates. The raw data were analyzed based on age stage two-sex life table theory with TWO SEX-MS Chart software.

The intrinsic rate of increase (r) were 0.2188 and -0.0199 day-1, the finite rate of increase (λ) were 1.244 and 0.0980 day-1, the net reproductive rate (R0) were 21.52 and 0.74 (eggs/individual), the mean generation time (T) were 14 and 16.75 days, and the gross reproduction rate (GRR) were 48.37 and 5.7 (eggs/individual) on Spinacea oleracea and Calendula officinalis, respectively.

The results showed that Calendula officinalis affect T. urticae negatively and only 10% of the mite population can mature on this host. Spinacea oleracea had no inhibitory effect on the biology of T. urticae and the performance of this mite on this host was like its performance on its main hosts. Calendula officinalis has juvenoid compounds that have negative effects on biology of T. urticae. So these compounds can be used in the management of T. urtcae.

Background and Objectives The accurate identification of taxons especially species and genera is very important for a better understanding of biology, ecology, life cycle and other aspects such as pathogenicity. Materials and Methods In order to identify plant parasitic nematodes associated with oak trees of Khoramabad city, Iran, 82 soil and foliar samples of oak trees were collected from different regions of Khoramabad city, during 2014 and 2015. After extraction, killing and fixation of nematodes, identification of species was carried out considering morphological and morphometrical characters using a digital camera equipped light microscope. Results In this study, 26  nematodes species From Tylenchomorpha infraorder and Longidoridae family including: Aphelenchus avenae,Laimaphelenchus australis L. penardi, Paraphelenchus amblyurus,Aprutides guidetti, Ditylenchus medicaginis, D. anchilisposomus,D. parvus,Mesocriconema antipolitanum,Amplimerlinius globigerus, Scutylenchus rugosus, Merlinius brevidens, M. nanus,Trophurus ussuriensis, Helicotylenchus digonicus, H. exallus, H. vulgaris, Pratylenchoides ritteri, Pratylenchus neglectus, P. thornei, Zygotylenchus guevarai, Boleodorus thylactus,Discotylenchus sp, Psilenchus hilarulus, Paratylenchus similis, and Xiphinema index were identified. Among the identified nematodes, 19 species are reported for the first time from oak tree in Iran. Laimaphelenchus australis is characterized by ventrally arcuate body; cephalic region set off; four incisures in lateral field; vulva without a flap, post-uterine sac extending for about one-third the vulva-anus distance, tail conoid with a single stalk-like terminus and four pedunculate tubercles.L. penardi male nematodes by are morphology similar to that of female, 12.9-13.1 μm long stylet, 25.2-26.0 μm long spicule, testis outstretched, spermatocytes in a single column, spicules paired, rosethorn–shaped, with prominent capitulum and rostrum broad with bluntly rounded tip. L. australis and male of L. penardiare new records for the nematofauna of Iran. These fungal nematodes are likely to affect the balance of endophytic fungi populations on oak trees, indicating the importance of identifying these nematodes, and D. anchilisposomus is re-described herein.

Different species of weevils (Col.: Curculionidae) are found in oilseed rape fields, which some of those are canola stem-borer weevils. They feed inside petioles, crown and/or stems of the crop in larval stages and cause damage. These weevils are mainly belonging to genus Ceutorhynchus, which little information about their taxonomy, distribution and biology is available in Iran.

During 2016-2018, the biological characteristics of canola stem-borer weevils were investigated in canola fields of Mazandaran, Lorestan and Golestan provinces. In each province, three fields were selected for collecting samples. Yellow water traps were used for weekly collecting adult weevils from the fields during crop growing season. For collecting weevil-infested crops and determining infestation rate, 10 quadrates (0.5 × 0.5 m) were used per field. The adult weevils collected by the traps were identified and the pest biology as well as the infestation rates of the crop by the weevils were studied.

In this study, five Ceutorhynchid species were collected and identified: C. picitarsis and C. chalybaeus from Mazandaran, C. erysimi and C. pallidactylus from Golestan and C. sulcicollis from Lorestan, Mazandaran and Golestan. In late November, the adult weevils migrated to canola fields and after feeding and mating, the females deposited their eggs into main veins, petioles of the lower leaves or inside of the collar area of young canola plants and the emerged larvae penetrated into the host plant. The three larval instars of this pest fed inside host plant tissue during autumn and winter till mid spring season. The feeding activity of the first and second instar larvae were observed in late November and late December, respectively. Third instar larvae were found from beginning until mid-spring season. In late April, third instar larvae left the host plant, dropped in the soil for pupation and new generation adults emerged in May. These weevils are univoltine. The results showed that, the maximum infestation rates of oilseed rape by the stem weevils in Mazandaran, Lorestan and Golestan provinces was 20.1±0.89, 14.8±1.29 and 10.2±0.29 percent, respectively.

Determining the time of adult migration activity, oviposiotion and larval development of the weevils is an integral part of pest management strategy in oilseed rape fields. In this study, flight and oviposition activity of adults and also feeding activity of the first instar larvae were mainly observed in late November, which suggests this time as a suitable time for chemical control, if necessary. These weevils are mostly distributed around the Caspian Sea region (Mazandaran and Golestan provinces) however more investigations are required to conclude the existence of those in other parts of country.