نشریه بوم شناسی علف های هرز
سال یکم شماره 2 (پاییز و زمستان 1392)

Eastern dodder is an obligate parasite of many orchard and ornamental plants which has caused extensive damages to them and city landscapes, in recent years. In order to control this parasite biologically, a research was done during 2010-11. Infected tissues of dodder were collected from fields and the city landascapes of Mashhad. One strain of Fusarium oxysporum which was identified with identification key was selected as the best strain and applied on dodder after its connection to the host in three experiments which were conducted using completely randomized designs in greenhouse. In these experiments of the effects of different concentrations of spore suspensions (104, 105, 106 and 107 spores ml-1), various dew periods (0, 6, 12, 18 and 24 hours) and host domain were investigated. Results indicated that the pathogenicity of isolate increased with increasing spore concentration. Therefore, the concentration of 107 spores ml-1 caused 20 percent reduction in dry mass of dodder. Increasing length of dew period caused more diseases. The result of the experiment showed the most severe pathogenicity and 32.9 percent reduction in dodder mass, in more than 18 hours of dew period. Consequently, it can be inferred that this strain has the potential ability of controlling the dodder.

This study was performed to evaluate the efficacy of some previous or recently registered herbicides for chemical weed control on forage sorghum in Mashhad (Iran) during 2010. The experiment was conducted in RCBD with four replications. Treatments were consisted of Mesotrion+S-Metolacholor+Terbuthlazine (Lumax 3 and 4 l ha-1 post and pre-emergence), Cinosulfuron (Setoff 250 and 375 g ha-1, pre-emergence), Oxadiagyl (Topstar 3 and 4 l ha-1, pre-emergence), Trifluralin (Treflan 1 l ha-1), Trifluralin+Atrazin (2 l ha-1+1.5 Kg ha-1), 2,4-D+Banvel+Atrazine (Dialant 1 l ha-1+Atrazine 1kg ha-1), along with weed free and weed infested controls. The results showed that Lumax, Treflan, Treflan+Atrazine and Atrazine+Dialan with 85-95 percent reduction were the most successful in weed suppression while Setoff and Topstar with35% reduction were relatively unsuccessful. Also, the mention treatments were the most efficient to saving forage yield of sorghum while it was decreased in post emergence application of Setoff 375 gr ha-1 and Lumax 4 l ha-1. Application of Lumax caused a temporary injury symptoms early season in sorghum.The most important weeds were Amaranthus retroflexus, Chenopodium album, Portulaca oleracea, Convolvulus arvensis and Solanum nigrum.

The effect of chemical and flaming methods on control of Vetiver grass was investigated at laboratory greenhouse of Khorasan Razavi Agricultural Research Center during 2010 and 2011. Two experiments were laid out in randomized complete block designs with four replications. Chemical control treatments were consisted of application of Glyphosate (Round-up 41% SL) at doses of 6 L.ha-1 and 10 L.ha-1 plus 2% (v/v) ammonium sulfate, Haloxyfop-R-methyl (Galant Super EC10.8) at the rate of 1 L.ha-1. Treatments were applied at two growth stages (the early vegetative and onset of generative growth stage). To apply flaming, mature plants were exposed to flame in durations of 0, 10, 30 and 60 seconds. Flaming and herbicide efficiency were visually evaluated after 14 days. Furthermore, plants were harvested after 30 and 60 days. Number of tillers, fresh and dry weight of shoot and root were recorded. The results showed that flaming was not able to control vetiver grass at least at the range of flaming durations applied under this study. Glyphosate could control plant growth even at its lowest dose.

In order to investigate the status of Iran's research on broomrape in comparison with the global research, information relating to the 1398 weed reports, published in Farsi during the last 40 years, and 1477 English articles (2004-2011) related to the world’s weed research, was analyzed in a database. The proportion of parasitic plants, broomrape and dodder (Cuscuta spp.) articles, among with the total weed articles in Iran, were, six, four and two percent respectively and Striga sp was observed in only one article. World studies in the broomrape were about four percent of the total while the share of the broomrape was about 50% of total parasitic plant’s research. Results also revealed that 75% of the Iranian broomrape studies are sponsored by research centers who are affiliated to the Ministry of Jehad-Agriculture. The check cleared that the broomrape research share to total weed research in Iran and the world is declining, probably due to the increasing diversity of scientific disciplines in the field of weed science. However, globally the broomrape research growth is more than any other parasitic plant, where it should be for the specific properties of the parasite, its worldwide extension and its damaging potential compared with other parasitic plants. Studies in Iran gradually have been focused on identification, management and biological issues respectively while in the world, issues like biology and physiology studies of the parasites have been replaced by genomic studies, Strigolactones, induced host resistance, host-parasite interaction and studies of integrated management packages. Broomrape is one of the most important parasitic plants in Iran and the world, and its long history of research showed the fact that it still has not led to a comprehensive management solution. Despite the relatively long history of research on broomrape in Iran, these investigations are still young and not offer enough information about the weed species of broomrape in Iran. Evaluation of new management methods, in light of world's recent advances in molecular and genetic modification of crops, consistent with the framework conditions of the country, could be a wise strategy for future studies is this field.

In order to evaluate the effect of cotton (Gossypium hirsutum) and common lambsquarters (Chenopodium album) densities on yield and yield components of cotton, a field experiment was conducted in the Agricultural Research station in Birjand University, Iran. A factorial experiment was carried out in a complete block design with three replications. Treatments included weed density (0, 6, 9, 12 plants.m-2) and crop density (6, 9, 12 plants.m-2). Three pure stand of common lambsquarter densities (6, 9, 12 plants.m-2) was added to each block. Results indicated that there was a significant decrease in yield and yield components of cotton under weed densities. Six plants.m-2 of weed caused 15% decrease in seed cotton and increase of weed density up to 9 and 12 plants/m2 caused further decrease in seed cotton. These weed densities (6, 9 and 12 plants.m-2) caused 16, 30 and 45% decrease in cotton seeds respectively. Lint yield was decreased 13, 24 and 42% as weed density increased from 6 plants.m-2 to 9 and 12 respectively. In this experiment, increasing cotton density was able to soften the negative impact of increasing weed density. Increasing crop density can be utilized effectively to minimize cotton yield reduction due to weed interference.

This study was carried out to determine the effects of aqueous extracts of (cardaria draba L.) organs (root, stem, leaf and their mixture) on germination of sorghum. The experiment was laid out as a completely randomized design with factorial arrangement and in four replications in research lab of agricultural college at Birjand University in 2010. The treatments included aqueous extracts of root, stem, leaf and their mixture at concentration of zero (check), 10, 20, 40 and 80 percent. According to the results, extracts of different tissuess on germination and root length could be 5% on level, and the germination rate and number of lateral roots was significantly different at 1% percent. The effect of white top extract concentration on all measured traits were significant at 1%. Infact, different organs and concentrations of white top affects considerably prevential on germination of sorghum seeds. Similar results were observed in concentration of 80% by volume, So that the largest percentage of decline in sorghum seed germination (22.5%) were related to the recent treatment.