The Weed's News Digest

The Weed's News email digest contains a summary of activity for the time period October 5, 2012 through October 11, 2012.
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The Weed's News Articles

Spray then play? Colorodo parents say no way and cancel soccer games

David Low / WeedsNews3856 / October 11, 2012 / 1:41:49 PM EST / 0 Comments
[ 06 Oct 2012 by Paul Turkey] -- Widespread disagreement exists in the scientific and medical communities about when, or if, fields are safe — especially for young children — after pesticides have been sprayed. In more than 80 percent of Canada, as well as the states of New York and Connecticut, pesticides used to kill weeds are against the law in schoolgrounds and parks where young children play. All pesticides state “Keep Out of the Reach of Children,” yet that’s obviously not happening on youth fields where the products are sprayed. The USA city of Durango, Colorado, has made a lot of headlines in its local newspaper recently by renouncing a petition drive to ban pesticides — then reversing its field and agreeing to work with the pesticide petitioners after all. It now appears the local residents have been reading the fine print. Although the town officials voted unanimously to adopt a pesticide policy on town-owned property going forward in 2013, they didn’t cancel contracts for spraying synthetic chemical weed killers this fall. With a main soccer field scheduled to be sprayed Friday, Oct. 12, many parents and coaches have revolted. [Photo caption: This photo, taken by Tim Faulkner in Rhode Island last year, shows dozens of people ignoring a re-entry period of 48 hours after a pesticide spraying. In Durango, Colorado, some parents are taking action.] Comment

University of Colorado goes organic on its lawns

David Low / WeedsNews3854 / October 11, 2012 / 1:20:45 PM EST / 0 Comments
[ 05 Oct 2012 by Paul Tukey] BOULDER, CO. — Showcasing what is likely the largest compost tea project of its kind anywhere in the nation on Thursday, Oct. 4, the lead turfgrass manager at the University of Colorado offered a behind-the-scenes look at what makes his 70-plus acres of grass truly green. The compost tea, a biologically active liquid — that some in academia claim is just brown water — is sprayed through the entire campus sprinkler system. The result is remarkably beautiful grass that is safe and luxuriant for the school’s 29,000-plus students and faculty. “It was a huge challenge to figure everything out,” said Ryan Heiland, the former golf course superintendent who was hosting a group of lawn care professionals from across the nation. “On one side you have people who just hate dandelions,” he said. “On the other side, you have people who hate the spraying of pesticides just as much, or even more. So my response was to just start using organic fertilizers and methods as an experiment. Then we used them on the entire quad for two years before we told anyone about it. That way no one could tell us that it didn’t work. You stand there and look at the grass and it speaks for itself. Comment

Effect of interseeding cover crops and fertilization on weed suppression under an organic and rotational cropping system

Zheljana Peric / WeedsNews3851 / October 11, 2012 / 12:14:38 PM EST / 0 Comments
Abstract: Interseeding cover crops is an alternative to laborious intertillages and hand weeding followed in organic farming. The objective of this study was to evaluate the effect of fertilization and interseeding cover crops on the growth of main crops and weeds and the stability of weed suppression over years and main crop species under four-year rotational organic farming. Two cover crops, winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), were interseeded in furrows of potato (Solanum tuberosum L.), soybean (Glycine max Merr.) and maize (Zea mays L.) at 3–5 weeks after planting the main crops. The number and dry weight of weeds were measured at the maximum plant height stage of main crops and main crop yields were recorded at their physiological maturity. The light competition between main crops, cover crops and weeds was analyzed by vertical community structure and vegetation cover ratio (VCR) of each crop. Since light competition of main crops with cover crops and weeds was not severe, main crop yields were not suppressed significantly by either cover crops or weeds. Weed growth was suppressed significantly by interseeding cover crops through increasing the VCR of main crops plus cover crops. This weed suppression by interseeding cover crops was stable to the main crop species in rotational cropping systems and to the various environmental conditions, because the cover crops compensated the low VCR of main crops alone at early growth stage especially when main crop growth was depressed by unfavorable environmental conditions. In addition, input of compost and fermented organic fertilizer had positive effects on the main crop yield and weed suppression. It is concluded, therefore, that weeds can be suppressed effectively and stably without yield reductions of main crops by interseeding cover crops with sufficient fertilization in organic farming systems. [Uchino, Iwama, Jitsuyama, Ichiyama, Sugiura, Yudate, Nakamura, Gopal (2012). Effect of interseeding cover crops and fertilization on weed suppression under an organic and rotational cropping system: 1. Stability of weed suppression over years and main crops of potato, maize and soybean. Field Crops Research. 127(27):9-16.] Comment

Ecology and impacts of the invasive species, Lantana camara, in a social-ecological system in South India: Perspectives from local knowledge

David Low / WeedsNews3845 / October 11, 2012 / 9:51:12 AM EST / 0 Comments
Abstract: We explored how the forest-dwelling Soliga community of South India views and explains biological invasions, and how local knowledge can inform scientific knowledge on biological invasions. We used an interview schedule with open-ended questions to solicit Soliga opinion on Lantana camara (lantana) invasion. The Soliga cited three reasons for lantana spread: its prolific fruit output and wide seed dispersal, change in fire management, and historical extraction of grass and bamboo. The Soliga believe that lantana invasion has had negative effects on the ecosystem and their livelihoods. Tabling scientific knowledge with local knowledge has improved our understanding of lantana invasion. The role of existing lantana in colonizing neighboring areas, and the response of native tree communities to lantana were common to both local and scientific sources. However, the Soliga view provides a more nuanced perspective of the lantana-fire relationship (contextually based on lantana density) with fires suppressing lantana when lantana density was low. This is contrary to views held by foresters and biologists, that fires are uniformly detrimental and promote lantana. Our study shows that examining Soliga observations has improved understanding of the invasion process and presents avenues for future lantana management. [Bharath Sundaram, Siddhartha Krishnan, Ankila J. Hiremath & Gladwin Joseph (2012). Ecology and impacts of the invasive species, Lantana camara, in a social-ecological system in South India: Perspectives from local knowledge. Human Ecology, online 02 Oct. DOI:10.1007/s10745-012-9532-1] Comment

Glyphosate exposure in a farmer’s family

David Low / WeedsNews3843 / October 11, 2012 / 7:22:42 AM EST / 0 Comments
Abstract: We tested the presence of glyphosate in the urines of a farmer who sprayed a glyphosate based herbicide on his land, and in his family, as his children were born with birth defects that could be due to or promoted by pesticides. Glyphosate residues were measured in urines a day before, during, and two days after spraying, by liquid chromatogra-phy-linear ion trap mass spectrometry. Glyphosate reached a peak of 9.5 μg/L in the farmer after spraying, and 2 μg/L were found in him and in one of his children living at a distance from the field, two days after the pulverization. Oral or dermal absorptions could explain the differential pesticide excretions, even in family members at a distance from the fields. A more detailed following of agricultural practices and family exposures should be advocated together with in-formation and recommendations. [R. Mesnage, C. Moesch, R. Grand, G. Lauthier, J. Vendômois, S. Gress & G. Séralini (2012). Glyphosate Exposure in a Farmer’s Family, Journal of Environmental Protection, 3(9), 1001-1003. doi: 10.4236/jep.2012.39115.] Comment

Spread dynamics and agricultural impact of Sorghum halepense, an emerging invasive species in Central Europe

David Low / WeedsNews3841 / October 10, 2012 / 10:11:50 AM EST / 0 Comments
Abstract: Sorghum halepense is a serious weed and reservoir for pathogens of crops worldwide that has recently spread in Austria. On the basis of an exhaustive distribution data set (302 records), we analysed the spread dynamics and agricultural impact. The first record of S. halepense was recorded in 1871, but the species remained rare until 1970. After a moderate increase in records until 1990, it has recently expanded strongly (>70% of all records have been collected since 1990), in particular, in the lowlands of eastern and southern Austria. Invasion into fields was first documented in the 1970s, but again, since 1990, S. halepense has spread strongly and fields now account for 32% of all records. In southern Austria, we found that S. halepense invasion already puts approximately 41% of grain maize fields and 40% of oil-pumpkin fields at risk of yield losses. In cooler regions within Austria, S. halepense is still rarely recorded in fields. Sorghum halepense serves as a reservoir for the maize dwarf mosaic virus, as it was found in 38% of 21 samples collected in southern Austria. Invasion of S. halepense in fields was most likely assisted by frequent secondary dispersal and intensive maize and oil-pumpkin cultivation. Given the fast and on-going spread in fields, which is likely to continue under climate warming, our results provide evidence that S. halepense will cause serious impacts for agriculture in Austria and probably in other countries of Central Europe. [Follak S & Essl F (2012). Spread dynamics and agricultural impact of Sorghum halepense, an emerging invasive species in Central Europe. Weed Research, online 09 Oct. DOI: 10.1111/j.1365-3180.2012.00952.x] Comment

The effectiveness of classical biological control of invasive plants

David Low / WeedsNews3838 / October 10, 2012 / 8:53:08 AM EST / 0 Comments
Abstract: Invasive alien plants have serious economic and ecological impacts, for example, by displacing native plants and invertebrates, and their management is often costly and ineffective in the long term. Classical biological control using specialized, coevolved natural enemies from the native region of the invader is often advocated as a preferred alternative to chemical and mechanical control, but there is a lack of quantitative assessment of control of the target species and subsequent establishment of native vegetation and invertebrates. Meta-analyses were carried out combining the results of 61 published studies (2000–2011) that quantified the impact of classical biocontrol at the level of individual target plants, target populations or non-target vegetation. Factors associated with the control programmes (invasive region, native region, plant growth form, target longevity, control agent guild, taxonomy and study duration) were analysed to identify patterns in control success. On average, biocontrol agents significantly reduced plant size (28 ± 4%), plant mass (37 ± 4%), flower and seed production (35 ± 13% and 42 ± 9%, respectively) and target plant density (56 ± 7%). Beetles in the Chrysomelidae and Curculionidae families were more effective at reducing plant size than other groups. Non-target plant diversity significantly increased by 88 ± 31% at sites where biocontrol agents were released, but it was largely unclear whether the replacement plant species were native or invasive. Synthesis and applications: The number of studies that provide quantitative indications of the effectiveness of biocontrol and the response of non-target taxa has increased over the past decade, but remains small compared to the total number of publications on the classical biocontrol of invasive plants. Nonetheless, this study demonstrates the positive impacts of classical biocontrol and the re-establishment of native plants in a broad range of systems and establishes the value of classical biocontrol for the control of invasive alien plants. The Chrysomelidae and Curculionidae families were the most effective agents and we recommend these be prioritized in cases where potential agents of different taxa have also been identified. In addition, data on the recovery of native plant species and the invertebrate community remain sparse and it is recommended that future studies report the identity of plant species that replace target species as well as invertebrate community responses. [Clewley, G. D., Eschen, R., Shaw, R. H., Wright, D. J. (2012). The effectiveness of classical biological control of invasive plants. Journal of Applied Ecology, online 05 Oct. doi: 10.1111/j.1365-2664.2012.02209.x] Comment

Sheep production as a Senecio spp. control tool

David Low / WeedsNews3836 / October 7, 2012 / 12:05:41 AM EST / 0 Comments
Abstract: Since poisoning by Senecio spp. is one of the main causes of cattle death in southern Brazil, control of these plants is a priority for the local livestock production. After the pasture has been mowed, grazing by 16 sheep was efficient for controlling Senecio brasiliensis and Senecio madagascariensis populations in a 5.5-hectare area that had long been severely infested with these species. A total of 28,629 plants among S. brasiliensis (flower-of-souls, 10,122) and S. madagascariensis (fireweed, 18,507) were almost completely eliminated in a two-year period. The number of sheep was kept at 3.0 stock units/ha, but a variable number of cattle were temporarily stocked according to pasture availability. The major sanitary practice applied to the sheep was anthelmintic administration. Liver biopsies taken from sheep and cattle before and after experimental period didn’t reveal any change associable with seneciosis. The performance levels of the sheep were comparable to those observed in flocks managed under traditional extensive grazing systems in southern Brazil. [Bandarra P.M., Oliveira L.G., Dalto A.G., Boabaid F.M., Juffo G., Riet-Correa F., Driemeier D. & Cruz C.E.F. (2012). Sheep production as a Senecio spp. control tool. Pesquisa Veterinária Brasileira, 32(10):1017-1022] [Photo caption: The Senecio brasiliensis populations infesting the contiguous area adjacent to but on the other side of the fence that limits the sheep paddock.] Comment