Search

Alkaliweed (Cressa truxillensis) is a native perennial plant of the western USA and in California, they are found primarily in saline and alkaline soils. Lately, it has been observed in Central Valley pistachio, olive, and almond orchards as a problematic species. Very little information is available on the effect of environmental factors on germination, shade tolerance, and the response of this species to herbicides. Therefore, studies were conducted to assess the effect of environmental factors (water potential, salinity, and pH) on seed germination, the influence of shade (30% shade 70% shade, and no shade) on aboveground growth, and the response of alkaliweed to common registered post-emergent herbicides. Results showed that the seeds were moderately tolerant to drought but highly adapted to salinity and pH as germination occurred up to an electrical conductivity level of 20 dS m−1 and pH range of 5 to 9. Both shade levels reduced aboveground growth and formation of reproductive structures. None of the postemergence herbicides provided adequate control of the plants. Therefore, an integrated management plan needs to be developed for alkaliweed control in Central Valley orchards. [ABSTRACT FROM AUTHOR]

Weed control is an important aspect during the first few years of Christmas tree establishment, as weed competition directly relates to the rate of Christmas tree growth during this time. The objectives of this study were to evaluate the weed control efficacy of organic mulch and herbicide combinations and to determine their phytotoxic effects on four different species of Christmas trees during the establishment stage: Fraser fir (Abies fraseri (Pursh) Poir), blue spruce (Picea pungens Engelm.), white pine (Pinus strobus L.), and Scotch pine (Pinus sylvestris L.). Twelve weed control treatments were established in a complete randomized block design with four replications in each of five fields. Weed control treatments included cypress bark organic mulch and herbicides applied alone and in combinations as well as an untreated control. Herbicides included clopyralid, oxyfluorfen, and glyphosate. All herbicides were applied at their highest labeled rate. Data collection included visual estimations of weed control and phytotoxicity to trees at 30, 60, and 90 days after treatment (DAT). Tree growth and foliar nitrogen concentration were also measured. Mulch combined with herbicide provided 60%–100% weed control in all cases; at two farms, mulch provided a significant increase in weed control when compared to the same treatments without mulch. Combinations of mulch + clopyralid + glyphosate and clopyralid + oxyfluorfen + glyphosate resulted in the highest phytotoxicity ratings. Tree growth was decreased due to some treatments at Gobles farm, and foliar N did not differ among any of the treatments. [ABSTRACT FROM AUTHOR]

Alkaliweed (Cressa truxillensis) is a native perennial plant of the western USA and in California, they are found primarily in saline and alkaline soils. Lately, it has been observed in Central Valley pistachio, olive, and almond orchards as a problematic species. Very little information is available on the effect of environmental factors on germination, shade tolerance, and the response of this species to herbicides. Therefore, studies were conducted to assess the effect of environmental factors (water potential, salinity, and pH) on seed germination, the influence of shade (30% shade 70% shade, and no shade) on aboveground growth, and the response of alkaliweed to common registered post-emergent herbicides. Results showed that the seeds were moderately tolerant to drought but highly adapted to salinity and pH as germination occurred up to an electrical conductivity level of 20 dS m−1 and pH range of 5 to 9. Both shade levels reduced aboveground growth and formation of reproductive structures. None of the postemergence herbicides provided adequate control of the plants. Therefore, an integrated management plan needs to be developed for alkaliweed control in Central Valley orchards.

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cleavers (Galium aparine L.) causes severe problems in winter wheat (Triticum aestivum). Four field experiments were performed at Kayakenstky and Stalskiy regions, southern Russia over two growing winter seasons 2015 and 2016 to evaluate postemergence (POST) applications of herbicides (Flucarbazone, metsulfuron, 2,4-D, fluroxypyr, tribenuron, pyroxsulam and sulfosulfuron) applied alone or in tank mixtures on winter wheat cultivars. Wheat injury from herbicide application was minor, with the exception of pyroxsulam + sulfosulfuron in 2015, and tribenuron + pyroxsulam in 2016 at Kayakenstky. Best cleavers control was observed in treatments containing tribenuron. Cleavers were controlled least by metsulfuron (study 1) and flucarbazone (study 2), whereas cleavers had intermediate growth inhibitory responses to the other treatments. Tribenuron + fluroxypyr applied in wheat 'Krasnodar 99', and tribenuron + pyroxsulam in wheat 'Gerda' resulted in enhanced grain yield with the value of 60% and 45.7%, respectively. Overall, tribenuron and herbicides containing tribenuron provided the most efficient control compared to the other herbicides and consistently maintained optimal grain yields in all cases. To improve weed control and to prevent a rapid development of herbicide resistance, tribenuron should be applied in combination with either fluroxypyr, pyroxsulam or metsulfuron. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reed canarygrass (Phalaris arundinacea L.) is an invasive species that forms dense, monotypic stands in wetlands, moist meadows, and riparian areas. We implemented a reed canarygrass removal study at five sites in eastern South Dakota using imazapyr, imazapic, and glyphosate individually and in combination. Eight treatments (five in fall, two in spring, and a control) were applied at each location in fall 2005-spring 2006. Herbicides were applied over clipped vegetation that had residual vegetation removed. Reed canarygrass cover was 93% in untreated plots, and ranged from 21%-66% in herbicide treated plots at the conclusion of the study. Herbicide treatments containing imazapyr provided control for two growing seasons. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Creeping bentgrass (Agrostis stolonifera L.; CBG) is a common weed in home lawns and golf course roughs in many regions of the United States. Currently, no herbicides are registered for selective control of CBG in cool-season grasses. The objective of this field study was to evaluate the ability of mesotrione and triclopyr ester to selectively remove CBG from Kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinacea Schreb.). Mesotrione (0.14 and 0.21 kg⋅ha-1 a.i.) and triclopyr ester (0.56 and 1.12 kg⋅ha-1 a.i.) were applied on a 2-week interval two, three, or four times in Connecticut and Maryland in 2005, and three or four times in Maryland in 2006. Two applications of mesotrione at 0.21 kg⋅ha-1 a.i. provided marginally acceptable CBG control, but three or four applications at 0.14 or 0.21 kg⋅ha-1 a.i. provided excellent CBG control. Mesotrione elicited little or no injury to Kentucky bluegrass, but generally caused objectionable injury in tall fescue for about 7 to 14 d after each application. Triclopyr applied at 0.56 kg⋅ha-1 a.i. reduced CBG cover, but the level of control generally was unacceptable, regardless of application frequency. Three or four applications of triclopyr (1.12 kg⋅ha-1 a.i.) effectively controlled CBG in Connecticut in 2005 and Maryland in 2006. Triclopyr caused no visual injury to tall fescue, regardless of rate or application frequency. Four triclopyr applications to Kentucky bluegrass, however, were phytotoxic and reduced stand density, especially at the high rate (1.12 kg⋅ha-1 a.i.). Three summer applications of mesotrione (0.14 kg⋅ha-1 a.i.) or triclopyr (1.12 kg⋅ha-1 a.i.) provided the best combination of turfgrass safety and CBG control. Chemical names used: [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr ester); 2-[4-(methylsulfonyl)-2-nitrobenzoyl]-l,3-cycilohexanedione (mesotrione) [ABSTRACT FROM AUTHOR]

Abstract: Regional production of dry chile pepper (Capsicum annuum L.) is usually limited by an inappropriate weed management. Traditionally, weeds are mainly controlled by mechanical means such as cultivation and hand hoeing increasing production costs. The purpose of this research was to: (1) evaluate the efficacy of preplant-incorporated, premergence, and postemergence herbicides and (2) estimate the net profit of weed control treatments. In 2004, all herbicide treatments reduced weed density in comparison to the mechanical weeding 135 DAP, although trifluralin treatments were the less effective among herbicide treatments. In 2005, weed control with herbicides was similar to the mechanical weeding treatment, even though plots conventionally sprayed with oxyfluorfen showed the lowest weed dry matter. Whereas plots treated with oxyfluorfen through furrow irrigation showed the highest marketable yield in 2004, marketable yields from plots treated with oxyfluorfen, oxadiazon, or prometryne conventionally applied or glyphosate were higher than those from plots treated with preemergence herbicides sprayed through furrow irrigation in 2005. In both years, the use of trifluralin on wet soil resulted in the lowest benefit/cost relationship, whereas the use of prometryn sprayed through furrow irrigation requires of more study because of the low benefit/cost relationship. [Copyright &y& Elsevier]

Christmas trees are sensitive to weed competition, especially during establishment. In initial stages of the tree crop, weeds can utilize available soil moisture and trees may succumb to drought stress. In later stages, weeds can even interfere with production practices. Non-chemical weed control methods alone may not provide effective weed control. Chemical weed management strategies involve the use of preemergence and postemergence herbicides at the right timing and application rates. There are many herbicides that are used in Christmas tree production in the United States, and each has specific application guidelines and weed control spectra. Moreover, crop trees vary in tolerance by species and tree age. Growers need to be careful while applying herbicides as many of these chemicals can cause injury to Christmas trees. Repeated application of herbicides with the same mechanism of action has resulted in development of herbicide resistance among several weed species. Managing herbicide resistance has now become an important issue. More research is required on identifying and managing herbicide resistance among weed species in Christmas tree production. Future research needs to focus on herbicide and mulch combinations, herbicide rotations, and tank mixing different herbicides with different mechanisms of actions and how these affect Christmas tree varieties. [ABSTRACT FROM AUTHOR]

[Objective] The paper was to study efficacy and phytotoxicity of different dosages of 4% nicosulfuron on weeds in corn fields. [Method] With summer corn variety Zhengdan 958 commonly used in field production in Hengshui area of Hebei Province of China as the test material, different dosages (1 050, 1 500 and 1 950 mL /hm²) of corn postemergence herbicide 4% nicosulfuron SC were sprayed during five-leaf stage of corn, and the treatments with water spraying and manual weeding were set as controls. The effects of different dosages of 4% nicosulfuron SC on weed control efficacy and safety and yield of corn were analyzed in order to determine the optimal dosage. [Result] Spraying 4% nicosulfuron SC with dosage of 1 500 mL /hm² during five-leaf stage of corn not only had better control effect against various weeds, but also did not produce phytotoxicity on corn, and the yield of corn was higher. [Conclusion] The study provided scientific information for using 4% nicosulfuron to eradicate weeds in corn fields. [ABSTRACT FROM AUTHOR]

Field studies were conducted to evaluate postemergence combinations of halosulfuron plus sethoxydim or clethodim with various adjuvants for effects on jack-o-lantern pumpkin (Cucurbita pepo L.) injury and yields and control of large [Digitaria sanguinalis (L.) Scop.] and smooth crabgrass [D. ischaemum (Schreb. ex Schweig.) Schreb. ex Muhl.]. Halosulfuron caused 27% and 14% pumpkin injury at 28 d after postemergence treatment (DAPT) in 2004 and 2005, respectively. Tank-mixing sethoxydim or clethodim with halosulfuron did not increase pumpkin injury compared with halosulfuron alone. Pumpkin injury from sethoxydim and clethodim alone at 28 DAPT ranged from 19% to 23% in 2004, but was only 7% to 8% in 2005. The addition of oil-based adjuvants to halosulfuron did not affect pumpkin injury compared with using a nonionic surfactant (NIS). The tank mixture of halosulfuron and sethoxydim did not affect crabgrass control regardless of adjuvant. However, the addition of halosulfuron to clethodim plus NIS reduced control of crabgrass from 89% to 77% at 28 DAPT. Crabgrass control was unaffected by the addition of halosulfuron to clethodim with crop oil concentrate (COC) or a NIS/COC blend. None of the herbicide treatments provided pumpkin yield (fruit no./ha) similar to the weed-free control. The pumpkin yield of treatments using postemergence herbicides was at least 50% less than the weed-free treatment. These low pumpkin yields were most likely the result of the combination of pumpkin injury from the herbicide applications and insufficient weed control. [ABSTRACT FROM AUTHOR]

Effects of a mixture of the postemergence herbicides acifluorfen and bentazon, and simulated defoliation expected from green cloverworm on population densities of Heterodera glycines were determined in field plots in Iowa. The herbicide mixture and defoliation each suppressed soybean growth. Population densities of H. glycines were generally lower in herbicide-treated than untreated plots. Population densities of the nematode were unaffected by defoliation in 1988 and 1990-91, but were increased by the treatment in 1989.