JOURNAL OF WEED ECOLOGY
Year:2014 | Volume:2 | Issue:1|Papers Count:6

In order to control weeds in transplanting onions in southern Kerman province, an experiment was conducted based on randomized complete block design with 9 treatments and four replications during 2003-2004. The treatments included of Pendimethalin 33% in 4.5 L/ha (pre), Oxyfluorfen 24% in 2 L/ha (post), Oxadiazon 12% in 3 L/ha (pre and post), and Oxadiargyl WG and EC in 120 g/ha and 4 L/ha (post), respectively; plus weedy check .The results indicated that the application of herbicides decreased density and biomass of weeds and increased onion yield. Oxyfluorfen had maximum effect on reducing density and biomass of mallow (Malva parviflor L.), lambsquarter (Chenopodium album L.) and purple nutsedge (Cyperus rotundus L.). Barnyard grass (Echinochloa colonum L.) was successfully controlled by oxadiazon; lambsquarter was successfully controlled by all herbicides except Oxadiargyl; the highest onion yields belonged to Oxyfluorfen with 71.75 t/ha.

To control weed in SC704 corn inbred lines using new herbicides, an experiment was conducted in randomized complete block design with four replication and ten treatments in Agricultural Research Center and Natural Resources of Khorasan Razavi Province, in Mashhad during 2010. The treatments consisted of Nicosulfuron (Cruz 4%SC, 80 g ha-1), Nicosulfuron + Bromoxynil + MCPA (Nicosclfuron 4% SC+ Bromicid MA® 4%EC, 80 + 400 g ha-1), Rimsulfuron + Nicosulfuron (Ultima® DF75%, 90 and 127.5 g ha-1), Foramsulfuron (Equip 22.5% OD, 337.5 and 562.5 g ha-1), and Mesotrione+S-Metolachlor+Terbuthylazine (Lumax 537.5 SE, 1344 and 1881 g ha-1). Two treatments weed free and weed infested were also included as checks. The most frequent weeds were Amaranthus retroflexus L., Portulaca oleracea L., Solanum nigrum L., and Chenopodium album L. The results showed that all herbicides could significantly reduce the density and dry weight of weeds. The most efficient treatment for the weed control was Nicosulfuron+Bromoxynil+MCPA with 76.7% and 80.9% reduction of weed density and weed dry weight, respectively. Furthermore Mesotrione+S-Metolachlor+Terbuthylazine (1344 g ha-1) was the most efficient in reducing weed density and weed dry weight. Combination of Rimsulfuron+Nicosulfuron (90 g ha-1) with 0.936 t ha-1 was the most inefficient treatment for hybrid seed yield.

To investigate the effect of the duration of weed interference and Weed control on yield and yield components of corn as a second crop after rapeseed, an experiment was conducted in Moghan during 2010. the type of design was completely randomized block with 14 treatments and 4 replications per treatment. There were two series of treatments in order of weed interference at 10, 20, 30, 40, 50 and 60 days after corn emergence, and the second series, weed control up to the above stages plus weedy check and weed free throughout growing season. The results showed that the beginning of critical period of weed control (CPWC) was based on 5% and 10% accepted yield loss (AYL), from 1 to 3 days after crop emergence, respectively. The end of the CPWC varied from 5% AYL to 10% AYL/was equates to 67 and 52 days after corn emergence.

To investigate the efficiency of herbicides on weed control in tomato, an experiment was conducted on randomize complete block design with three replications in Chenaran - Khorasan Razavi - in 2010. The treatments included of herbicide dosage Sulfosulfuron (20, 40, 60 and 80 g ha-1), Aclonifen (1, 2, 3 and 4 L ha-1), Foramsulfuron (1, 1.5, 2 and 2.5 L ha-1) and Metribuzin (100, 200, 300 and 600 g ha-1).The control plots were consisted as weed free and weedy check, respectively. In order to measure weed density, dry matter, weed control percentage and evaluating herbicide effect on tomato based on EWRC, sampling was taken before herbicide application and 20 days after herbicide treatments. At the end of growing season, traits such as tomato per plant dry matter, per plant yield and total tomato yield was measured. Metribuzin, Sulfosulfuron, Foramsulfuron and Aclonifen provided weak to satisfactory level of weed control, respectively. On the other hand, the lowest weed dry matter and weed density was found at high doses of herbicides that was associated with damage to tomato. Foramsulfuron, Sulfosulfuron and Metribuzin/ resulted the highest tomato dry matter. the highest tomato plant yield, gained by Metribuzin and Aclonifen herbicides, respectively. Totally, Aclonifen (2 and 3 L ha-1), Foramsulfuron (1.5 L ha-1), Metribuzin (300 g ha-1) and Sulfosulfuron (20 g ha-1) not only provided optimal weed control, but also high tomato yield with minimal damage to crop.

The effect of hand weeding and the type of herbicides application on yield and yield components of cotton was investigated as factorial arrangement based on rrandomized complete block design with 3 replications in Davarzan section of Sabzevar.The factors of the study included of the type of herbicide at 4 levels (soil incorporated, post emergence, incur porated soil + post emergence, and control) and weeding number at 3 levels (weedy check, once and twice hand weeding). Trifluralin (1200 gai/ha) and Trifloxysulfuron sodium (15 gai/ha with cytogate 2/1000) were selected as pre plant soil incorporated herbicides and post emergence herbicide, respectively. The result showed that twice hand weeding had the highest economic yield. There wasn’t significant difference between once and twice weeding for economic yield. Between yield components, the number of boll and reproductive branches were affected more by times of weed control, especially two times weed control. The highest yield and yield component were achieved in soil applied + plus post emergence treatment. Although post emergence application herbicide had more yield but did not control weeds effectively. Overall, applied soil + post emergence treatment plus one time hand weeding provide a good weed control and gained suitable economic yield.

Weed identification is considered the most fundamental task in weed management. It would be possible to decide on specific methods of weed control through availability of weed information in a particular location, otherwise applying different methods of control will not show satisfactory effects. Wheat is the most important crop in West Azerbaijan province so that more than 2000000 hectares are under wheat farming, based on Jihad Organization information. In order to identify dominance weeds and their density 48 fields were selected in 7 cities of West Azerbaijan province during 2004-2007. Based on Thomas method, a W pattern was selected considering the area of each field, and then 1m×1m quadrate was thrown accordingly. The genus and species within each quadrate were determined. By using specific formulas, the density, frequency and uniformity of each weed species were calculated. Geographic coordinates of each field (Latitude, Altitude and Elevation) were determined by using GPS. In irrigated wheat fields 52 weed species from 20 families were recognized from which. Sinapis arvensis L., Vicia sp; Conringia orientalis(L.) Andrz., and Fumaria parviflora Lam. had the highest density in irrigated wheat fields in West Azarbayjan province. The most dominant narrow leaf weeds were Secale cereale L., and Avena ludoviciana Dun.