The Weed's News Digest

The Weed's News email digest contains a summary of activity for the time period July 18, 2015 through July 31, 2015.
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The Weed's News Articles

Introduced reed canary grass attracts and supports a common native amphibian

David Low / WeedsNews5491 / July 29, 2015 / 10:37:48 PM EST / 0 Comments
Abstract: The control of introduced plants is frequently a demanding and expensive activity for wildlife managers. It can be difficult to suppress some well-established species, and control measures may harm native organisms. Reed canary grass (Phalaris arundinacea) is a common wetland invader that can dominate and greatly alter wetlands. To examine the relationship between this plant and native amphibians, we analyzed field survey data and quantified amphibian-plant relationships in constructed replicated experimental ponds. Surveys showed positive associations between reed canary grass and the abundance of 3 native amphibians in 62 natural and constructed urban and suburban ponds in Portland, Oregon. Experiments elucidated mechanisms whereby 2 native and 2 introduced plants influenced breeding habitat use and larval performance of the common native Pacific chorus frog (Pseudacris regilla). Males preferred to call from reed canary grass, and there was a strong trend for females to lay eggs on the invasive grass compared to other plants offered. Tadpoles had 7 times higher survival in reed canary grass. These patterns were likely due to the morphology of reed canary grass: it provides support for calling males, its leaves and shoots are of ideal size for oviposition, and its branching may provide effective refuges from predators. This study demonstrates that some introduced plants may be beneficial for some native amphibians. Improved understanding of the relationships between introduced plants and native wildlife can help guide management actions by recognising that the control of introduced plants may not be a priority in all systems. [Holzer, K. A. and Lawler, S. P. (2015). Introduced reed canary grass attracts and supports a common native amphibian. The Journal of Wildlife Management, online 18 July] Comment

Effects of the herbicide dicamba on non-target plants and pollinator visitation

David Low / WeedsNews5489 / July 29, 2015 / 9:56:02 PM EST / 0 Comments
Abstract: Nearly 80% of all pesticides applied to row crops are herbicides, and these applications pose potentially significant ecotoxicological risks to non-target plants and associated pollinators. In response to the widespread occurrence of weed species resistant to glyphosate, biotechnology companies have developed crops resistant to the synthetic-auxin herbicides dicamba or 2,4-D, and once commercialized, adoption of these crops is likely to change herbicide-use patterns. Despite current limited use, dicamba and 2,4-D are often responsible for injury to non-target plants, but effects of these herbicides on insect communities are poorly understood. To understand the influence of dicamba on pollinators, we applied several sub-lethal, drift-level rates of dicamba to alfalfa (Medicago sativa L.), and Eupatorium perfoliatum L. and evaluated plant flowering and floral visitation by pollinators. We found that dicamba doses simulating particle drift (≈ 1% of the field application rate) delayed onset of flowering and reduced the number of flowers of each plant species; however, plants that did flower produced similar quality pollen in terms of protein concentrations. Further, plants affected by particle drift rates were visited less often by pollinators. Because plants exposed to sub-lethal levels of dicamba may produce fewer floral resources and be less frequently visited by pollinators, use of dicamba or other synthetic-auxin herbicides with widespread planting of herbicide-resistant crops will need to be carefully stewarded to prevent potential disturbances of plant and beneficial insect communities in agricultural landscapes. [Eric W. Bohnenblust, Anthony D. Vaudo,J. Franklin Egan, David A. Mortensen & John F. Tooker (2015). Effects of the herbicide dicamba on non-target plants and pollinator visitation. Environmental Toxicology & Chemistry, online 17 July] Comment

Effects of sub-lethal doses of glyphosate on honeybee navigation

David Low / WeedsNews5487 / July 29, 2015 / 8:50:14 PM EST / 0 Comments
Abstract: Glyphosate (GLY) is a herbicide that is widely used in agriculture for weed control. Although reports about the impact of GLY in snails, crustaceans and amphibians exist, few studies have investigated its sub-lethal effects in non-target organisms such as the honeybee Apis mellifera, the main pollen vector in commercial crops. Here, we tested whether exposure to three sub-lethal concentrations of GLY (2.5, 5 and 10 mg/L corresponding to 0.125, 0.250 and 0.500 µg/animal) affects the homeward flight path of honeybees in an open field. We performed an experiment in which forager honeybees were trained to an artificial feeder, and then captured, fed with sugar solution containing GLY traces and released from a novel site (the release site, RS) either once or twice. Their homeward trajectories were tracked using harmonic radar technology. We found that honeybees that had been fed with solution containing 10 mg/L GLY spent more time performing homeward flights than control bees or bees treated with lower GLY concentrations. They also performed more indirect homing flights. Moreover, the proportion of direct homeward flights performed after a second release at the RS increased in control bees but not in treated bees. These results suggest that, in honeybees, exposure to GLY doses commonly found in agricultural settings impairs the cognitive capacities needed to retrieve and integrate spatial information for a successful return to the hive. Therefore, honeybee navigation is affected by ingesting traces of the most widely used herbicide worldwide, with potential long-term negative consequences for colony foraging success. [María Sol Balbuena, Léa Tison, Marie-Luise Hahn, Uwe Greggers, Randolf Menzel & Walter M. Farina (2015). Effects of sub-lethal doses of glyphosate on honeybee navigation. The Journal of Experimental Biology, online July 10th] Comment

Rounding up the risk of glyphosate

David Low / WeedsNews5485 / July 29, 2015 / 7:51:50 PM EST / 0 Comments
[EchoNews 16 July 2015 by Sarah Brookes] AUSTRALIA -- Kalamunda Shire is reviewing its use of glyphosate in the wake of the World Health Organisation’s International Agency for Research on Cancer (IARC) labelling the pesticide as “probably carcinogenic to humans.Shire chief executive officer Rhonda Hardy said the shire used 1400 litres of the chemical, commonly marketed as Roundup, each year on shire-owned buildings, gardens, road reserves and fire breaks. “In light of the recent developments the shire is pursuing further information from state and federal governments regarding the potential future use of this substance and any associated risks,” she said. The City of Swan and Shire of Mundaring said it was guided by the Australian Pesticides and Veterinary Medicines Authority (APVMA) that states the label instructions on all glyphosate products, when followed, provided adequate protection for users. Shire of Mundaring acting CEO Paul O’Connor said the shire regularly reviewed the use of all chemicals used within the shire, including glyphosate. “The shire is committed to ensuring the health and safety of our community, employees and contractors,” he said. “Should the advice regarding the use of glyphosate change, the shire will liaise with the Department of Health in regards to the appropriate action.City of Swan CEO Mike Foley said the city used 10,000 litres of glyphosate per annum. “The city reviews all chemicals to ensure that the best and most appropriate product is being used in targeting weed species,” he said. Mr Foley said other methods of weed control were less effective. “Generally the city uses mulch in all landscapes, however mulched areas still need to be sprayed,” he said. “The city did trial natural weed control methods, such as steam, however this was not effective practically or financially sustainable.

Monash University senior adjunct research fellow Dr David Low said the release of known carcinogens into the environment to manage weeds was not justifiable, especially when there were other effective alternative methods available.
“Whether non-chemical methods are ‘cost effective’ depends on what we include in the evaluation, and what we leave out,” he said. “For example, the cost of the hospital treatment for those who contract cancer because of herbicide use, or the cost of replacing ‘off-target’ vegetation, insects and animals damaged or killed by herbicides is usually not considered. “In countries where these are included in the assessment, non-chemical methods are considered superior from an economic standpoint.” | Continue reading …| Comment |

Connecticut bans toxic Lawn pesticides in municipal playgrounds statewide

David Low / WeedsNews5483 / July 29, 2015 / 7:19:52 PM EST / 0 Comments
[Beyond Pesticides, July 10, 2015] USA -- The Connecticut General Assembly last week passed legislation banning toxic lawn pesticides on municipal playgrounds, effective October 1, 2015. In the omnibus budget implementation Bill 1502 at Section 448 (p.563 at line 17579). The bill also improves the existing parents’ pesticide notification system by requiring school districts to provide at least 24-hour electronic notification any time a pesticide application is schedule to occur on school property (Secs. 445 and 446), as well as requiring and tracking the use of pesticides and integrated pest management (IPM) methods to reduce pesticide use on state properties (Sec. 449). “As we have recognised for many years in Connecticut, children are particularly endangered by pesticides – because these chemicals accumulate in kids’ growing bodies faster than for the rest of us,” said Rep. Andrew Fleischmann, House Chairman of the Education Committee, which drafted the 2005 and 2009 laws prohibiting pesticide use on school fields. “This measure represents a great step forward for our state, safeguarding our children from these toxic chemicals on town playgrounds – and ensuring that parents get notice when pesticides are used at public schools,” he added. “Time and time again pesticides have been shown to have serious health and environmental consequences, and it is critical that we begin limiting their use,” said State Senator Ted Kennedy, Jr., Chair of the Senate Environment Committee. “By keeping pesticides off of playgrounds and school property, we limit [children’s] exposure to those who are most likely to become ill as a result of them. Improving our state’s notification procedures will better inform parents about pesticide and herbicide applications at their children’s schools.” | Continue reading … | Comment |