Crop Science - HH-RA.org

Bibliography Tag: crop science

Liebman and Davis, 2009

Matt Liebman and Adam Davis, “Managing Weeds in Organic Farming Systems: An Ecological Approach,” In Organic Farming: The Ecological System, Ed: Charles Francis, 2009.

SUMMARY:

In this chapter, we describe major components of the weed management tool kit for organic farming, highlighting areas in which important advances have been made in the last decade. We then argue that instead of approaching the development of multitactic weed management strategies as a purely empirical, trial-and-error activity, the choice and deployment of weed management tactics should instead be informed by insights from ecological theory… Finally, we emphasize the need for ongoing dialog between empiricists and theoreticians and between scientists and farmers, so as to better direct scarce research resources and management time to where they are likely to be most beneficial. Multitactic weed management strategies informed by theory should be useful not just to organic farmers but also to conventional farmers who seek to reduce their reliance on herbicides due to concerns over herbicide resistance in weeds, rising production costs, and environmental and human health risks associated with herbicide exposure. FULL TEXT

Steckel, 2012

Larry Steckel, “Glyphosate-Resistant Weeds: Lessons Learned in Tennessee,” Presentation to the Iowa Soybean Association, On-Farm Network Conference, Ames, IA, February 16, 2012

SUMMARY:

Describes aggressive spread of glyphosate reisistant weeds and the importance of proactive management, including prevention and early detection and recommends herbicide protocols to control weeds. FULL TEXT

Mesnage et al., 2016

Robin Mesnage, Sarah Z. Agapito-Tenfen, Vinicius Vilperte, George Renney, Malcolm Ward, Gilles-Eric Séralini, Rubens O. Nodari & Michael N. Antoniou, “An integrated multi-omics analysis of the NK603 Roundup-tolerant GM maize reveals metabolism disturbances caused by the transformation process,” Nature: Scientific Reports, 2016, 6:37855, DOI: 10.1038/srep37855

ABSTRACT:

Glyphosate tolerant genetically modified (GM) maize NK603 was assessed as ‘substantially equivalent’ to its isogenic counterpart by a nutrient composition analysis in order to be granted market approval. We have applied contemporary in depth molecular profiling methods of NK603 maize kernels (sprayed or unsprayed with Roundup) and the isogenic corn to reassess its substantial equivalence status. Proteome profiles of the maize kernels revealed alterations in the levels of enzymes of glycolysis and TCA cycle pathways, which were reflective of an imbalance in energy metabolism. Changes in proteins and metabolites of glutathione metabolism were indicative of increased oxidative stress. The most pronounced metabolome differences between NK603 and its isogenic counterpart consisted of an increase in polyamines including N-acetyl-cadaverine (2.9-fold), N-acetylputrescine (1.8-fold), putrescine (2.7-fold) and cadaverine (28-fold), which depending on context can be either protective or a cause of toxicity. Our molecular profiling results show that NK603 and its isogenic control are not substantially equivalent. FULL TEXT

Horstmeier, 2017

Greg Horstmeier, ” Dicamba: Arkansas Plant Board Unanimously Sets Mid-April Limit,” AgFax, September 22, 2017.

SUMMARY:

The Arkansas State Plant Board reached a unanimous decision to ban dicamba use in the state from August 16 – October 31, 2018 in an attempt to mitigate damage from drift. This would allow spring and fall burndown and pre-emergence application, but not the over the top spraying on growing crops that the new formulation and dicamba resistant seeds are engineered for. Plus, the board passed a resolution commending the Arkansas weed scientists whose scientific integrity was questioned by Monsanto in their bid to persuade the board to reject the proposed ban. The story includes key new information about volatility research that was presented to the board as part of the hearing process. Herbicide industry reps continued to downplay volatility and point fingers at operator error, while independent weed scientists reported that their findings showed that while volatility was lower immediately after spraying, volatilization continued 36 to 72 hours after application, meaning that “over time the amount of volatility between old and new formulations was not statistically different.” The board also rejected Monsanto’s argument that drift damage appears to not have caused yield loss, and is therefore not important to address. Board members felt this is “beyond the point when you are talking about pesticide stewardship” and bristled at Monsanto’s characterization of the proposed ban as “arbitrary and capricious.” FULL TEXT

Monsanto, 2017b

Ty Vaughn for Monsanto, “Historic Testing of Our Dicamba Formulation, XtendiMax® with VaporGrip® Technology,” Monsanto website, August 24, 2017.

SUMMARY:

In response to criticism that volatility was not adequately studied, the this statement reviews Monsanto’s belief that they conducted extensive and “historic testing” of the new formulations, claiming a 90% reduction in volubility. FULL TEXT

Zobiole et. al, 2010b

Luiz Henrique Saes Zobiole, Rubem Silvério de Oliveira Jr., Robert John Kremer, Jamil Constantin, Carlos Moacir Bonato, Antonio Saraiva Muniz, “Water use efficiency and photosynthesis of glyphosate-resistant soybean as affected by glyphosate,” Biochemistry and Physiology, 2010, 97: 182-193, DOI: 10.1016/j.pestbp.2010.01.004.

ABSTRACT:

Previous studies comparing cultivars of different maturity groups in different soils demonstrated that early maturity group cultivars were more sensitive to glyphosate injury than those of other maturity groups. In this work, we evaluated the effect of increasing rates of glyphosate on water absorption and photosynthetic parameters in early maturity group cultivar BRS 242 GR soybean. Plants were grown in a complete nutrient solution and subjected to a range of glyphosate rates either as a single or sequential leaf application. Net photosynthesis, transpiration rate, stomatal conductance, sub-stomatal CO2, carboxylation efficiency, fluorescence, maximal fluorescence and chlorophyll content were monitored right before and at different stages after herbicide application; water absorption was measured daily. All photosynthetic parameters were affected by glyphosate. Total water absorbed and biomass production by plants were also decreased as glyphosate rates increased, with the affect being more intense with a single full rate than half the rate applied in two sequential applications. Water use efficiency (WUE) was significantly reduced with increasing rates of glyphosate. FULL TEXT

Londo et al., 2014

Jason Paul Londo, John McKinney, Matthew Schwartz, Mike Bollman, Cynthia Sagers, and Lidia Watrud, “Sub-lethal glyphosate exposure alters flowering phenology and causes transient male-sterility in Brassica spp,” BMC Plant Biology, 2014, 14:70.

ABSTRACT:

BACKGROUND: Herbicide resistance in weedy plant populations can develop through different mechanisms such as gene flow of herbicide resistance transgenes from crop species into compatible weedy species or by natural evolution of herbicide resistance or tolerance following selection pressure. Results from our previous studies suggest that sub-lethal levels of the herbicide glyphosate can alter the pattern of gene flow between glyphosate resistant Canola®, Brassica napus, and glyphosate sensitive varieties of B. napus and B. rapa. The objectives of this study were to examine the phenological and developmental changes that occur in Brassica crop and weed species following sub-lethal doses of the herbicides glyphosate and glufosinate. We examined several vegetative and reproductive traits of potted plants under greenhouse conditions, treated with sub-lethal herbicide sprays.

RESULTS: Our results indicate that exposure of Brassica spp. to a sub-lethal dose of glyphosate results in altering flowering phenology and reproductive function. Flowering of all sensitive species was significantly delayed and reproductive function, specifically male fertility, was suppressed. Higher dosage levels typically contributed to an increase in the magnitude of phenotypic changes.

CONCLUSIONS: These results demonstrate that Brassica spp. plants that are exposed to sub-lethal doses of glyphosate could be subject to very different pollination patterns and an altered pattern of gene flow that would result from changes in the overlap of flowering phenology between species. Implications include the potential for increased glyphosate resistance evolution and spread in weedy communities exposed to sub-lethal glyphosate. FULL TEXT

Johnson et. al, 2009

William G. Johnson, Vince M. Davis, Greg R. Kruger, Stephen C. Weller, “Influence of glyphosate-resistant cropping systems on weed species shifts and glyphosate-resistant weed populations,” European Journal of Agonomy, 2009, 31, 162-172, DOI: 10.1016/j.eja.2009.03.008.

ABSTRACT:

Glyphosate-resistant (GR) crops have facilitated increases in conservation tillage production practices and simplified weed control in GR corn, soybean, canola and cotton. Increased reliance on glyphosate, many times as the only active ingredient used, has resulted in weed species shifts and the evolution of weed populations resistant to glyphosate. However, weed shifts and the evolution of herbicide resistance are not new in regard to glyphosate use. Similar effects have been documented to many other historically important weed control advancements for agricultural crop production. GR crop technology was developed to utilize glyphosate for postemergence weed control and industry scientists suggested that there was little fear of weed shifts and resistance evolution due to the broad spectrum of weeds controlled by glyphosate. However, over the last decade, the most problematic weeds in agronomic cropping systems have shifted away from perennial grass and perennial broadleaf weeds to primarily annual broadleaf weeds. The evolution of several GR annual broadleaf weeds in GR cropping systems has been documented, and glyphosate resistance mechanisms in weeds are currently poorly understood. FULL TEXT

Yamada, 2009

T. Yamada, “Glyphosate interactions with physiology, nutrition, and diseases of plants: Threat to agricultural sustainability?,” European Journal of Agronomy, 2009, 31:3, 111-176.

ABSTRACT:

Not Available

FULL TEXT

Cakmak et. al, 2009

Ismail Cakmak, Atilla Yazici, Yusuf Tutus, Levent Ozturk, “Glyphosate reduced seed and leaf concentrations of calcium, manganese, magnesium, and iron in non-glyphosate resistant soybean,” European Journal of Agronomy, 2009, 31:3, 114-119, DOI: 10.1016/e.eja.2009.07.001.

ABSTRACT:

Greenhouse experiments were conducted to study the effects of glyphosate drift on plant growth and concentrations of mineral nutrients in leaves and seeds of non-glyphosate resistant soybean plants (Glycine max, L.). Glyphosate was sprayed on plant shoots at increasing rates between 0.06 and 1.2% of the recommended application rate for weed control. In an experiment with 3-week-old plants, increasing application of glyphosate on shoots significantly reduced chlorophyll concentration of the young leaves and shoots dry weight, particularly the young parts of plants. Concentration of shikimate due to increasing glyphosate rates was nearly 2-fold for older leaves and 16-fold for younger leaves compared to the control plants without glyphosate spray. Among the mineral nutrients analyzed, the leaf concentrations of potassium (K), phosphorus (P), copper (Cu) and zinc (Zn) were not affected, or even increased significantly in case of P and Cu in young leaves by glyphosate, while the concentrations of calcium (Ca), manganese (Mn) and magnesium (Mg) were reduced, particularly in young leaves. In the case of Fe, leaf concentrations showed a tendency to be reduced by glyphosate. In the second experiment harvested at the grain maturation, glyphosate application did not reduce the seed concentrations of nitrogen (N), K, P, Zn and Cu. Even, at the highest application rate of glyphosate, seed concentrations of N, K, Zn and Cu were increased by glyphosate. By contrast, the seed concentrations of Ca, Mg, Fe and Mn were significantly reduced by glyphosate. These results suggested that glyphosate may interfere with uptake and retranslocation of Ca, Mg, Fe and Mn, most probably by binding and thus immobilizing them. The decreases in seed concentration of Fe, Mn, Ca and Mg by glyphosate are very specific, and may affect seed quality. FULL TEXT

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