Volume-1 | Issue-2 (July-December) | Year 2019

KEYWORDS:

Weed science, Utilization, Weeds definitions of weeds

Abstract:

Marcel Proust, an influential 20th Century French novelist once said: “…The real voyage of discovery consists not in seeking new lands but seeing with new eyes…" I commend this quote and suggest that it applies to the way we should look at weeds in this 21st Century. In this Editorial for the second issue of the new journal - Weeds - I reflect upon some ideas that have shaped our recent discourses on weeds. It seems to me that the emerging generation of weed scientists may benefit from a dip into this history. As someone said: ‘without history, man is nothing’.

Email

nimal.chandrasena@gmail.com

Address

Current Address: Nature Consulting, 1, Kawana Court, Bella Vista, NSW 2153, Australia

KEYWORDS:

Agriculture, ethics, philosophy, production, values, Weed Science

Abstract:

Agriculture is the largest, most important interaction between humans and the environment. It is an essential human activity. Humans, the Earth's dominant species. Usually, know what we are doing, but we often do not know what we may be undoing. This paper will briefly address some of agriculture's major problems: sustainability, land, production, water, antibiotics, genetic modification, and technology. It asks two questions: How do you know what to do in agriculture and life? How do you know what you choose to do the right thing to do?

Email

r.zimdahl@colostate.edu

Address

Professor Emeritus, Colorado State University, Fort Collins, CO, USA 80524

KEYWORDS:

Asian-Pacific region, weeds, integrated weed management, herbicide resistant weeds

Abstract:

Reducing poverty and ensuring future food and nutritional security are significant concerns in the Asian-Pacific region, which is characterized by rapid population growth, food shortages, and an increasing changing climate. Efforts to increase crop productivity and reduce existing crop yield gaps, by identifying constraints, such as weeds and alleviating their negative impacts, are essential to meet the targeted food and nutritional security goals in the region. The prime objectives of the Asian-Pacific Weed Science Society (APWSS) have been the promotion of Weed Science in the region, by pooling and exchanging information on weeds, and capacity building in weed management. Over the past five decades, APWSS has held 26 Conferences in the region compiling information related to weeds and publishing those in peer-reviewed proceedings. In this review, we assessed the extent of achievement of these prime objective by analyzing the above research published in the APWSS Conference proceedings and related publications under major weed research themes and categories. We then used the results (% numbers of papers published) to understand the status of weed research in the region and the key drivers for the research agendas and to make suggestions for the future weed management research needs in the Asian-Pacific region. Herbicide-led research dominates weed research in the APWSS region. Herbicide use continues to be a critical weed management tool in the gradually developing nations and emerging economies of the region. However, herbicide-resistant weeds, shifts in weed floras, and the emergence of new weeds, such as weedy rice, and climate change, have become significant weed management challenges. The new herbicide molecule development and introduction have slowed down. Genetically modified Herbicide Tolerant Crops (HTC) have been introduced in some Asian-Pacific countries as a component of packages of Integrated Weed Management (IWM). However, the emergence of herbicidetolerant weeds, due to gene flow and non-adoption of stewardship guidelines, combined with human health and environmental concerns and lack of trained personnel, are limiting HTC introduction and adoption. Thus, weed research in the region must continue on IWM, to better integrate knowledge of weed ecology, biology, and best management practices into specific cropping situations. Genetic engineering to produce new competitive crops cultivars, weed management through automation, and artificial intelligence, a better understanding of weed responses to climate change, may provide innovative approaches to efficiently, economically, and ecologically manage weeds.

Email

anraojaya1@gmail.com

Address

ICRISAT Development Centre (IDC) and IRRI; 2 IDC, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru 502324 Telangana, India

KEYWORDS:

benefit: cost ratios, host specificity, low-risk, integrated control, biological weed control

Abstract:

Biological control of weeds has been conducted since 1902, resulting in over 500 biological control agents being intentionally released against nearly 200 weed species in over 90 countries. Collectively, 15 countries in Asia and 17 of the 22 countries and territories in the Pacific region have intentionally released over 80 biological control agents to help manage over 30 of their most invasive weeds. Many of these programmes, have been highly successful. In fact, globally, over a third of all weed biological control programmes have resulted in some form of control of the target weed, resulting in huge benefit: cost ratios of up to 4,000:1. In addition, there have been very few (<1%) unpredicted, sustained non-target impacts on native or economic plants by weed biological control agents. This is because biological control agents have co-evolved with their host plants and are thoroughly tested, sometimes collectively across numerous countries, against up to 280 plant species, before being released. Moreover, many biological control agents that have proved to be successful in one country have now been released in over 30 countries, with no recorded non-target impacts. Yet, despite these successes, many countries are still reluctant to implement weed biological control. Even countries that have had tremendous successes with weed biological control in the past have shied away from implementing biological control in recent times, stating that it is too risky or doesn’t work. Unfounded and unscientific statements such as “biological control agents could evolve or mutate to attack other plant species” or “climate change may affect their host range” are often used to justify not implementing biological control. As a result, landowners continue to spend millions of dollars to purchase and apply herbicides, when an integrated approach, which includes biological control, can reduce management costs and enhance control. The challenge, therefore, is to educate all stakeholders, including communities, in the safety and cost-effectiveness of weed biological control. There are numerous opportunities to introduce highly specific and very effective biological control agents from countries where they are being utilized successfully, into other countries where the target weed is problematic to help manage these species.

Email

michael.day@daf.qld.gov.au

Address

Department of Agriculture and Fisheries, Ecosciences Precinct, GPO Box 267, Brisbane, Queensland, 4001, Australia; 2 CABI, PO Box 633-00621, Nairobi, Kenya

KEYWORDS:

wheat, flumioxazin, flufenacet, littleseed canarygrass, Phalaris minor, clodinafop, herbicide resistance, isoproturon, pendimethalin, sulfosulfuron

Abstract:

We conducted field trials and pot experiment to evaluate the effectiveness of two herbicides - flumioxazin and flufenacet - for weed control in wheat (Triticum aestivum L.), particularly targeting littleseed canarygrass (Phalaris minor Retz.). In the field studies, conducted over four seasons (2012-13 to 2015-16), the littleseed canarygrass populations encountered in the fields were sensitive to herbicides. In the pot studies, the responses of both multiple herbicide-resistant (resistant to isoproturon, clodinafop, and sulfosulfuron) and sensitive populations were examined against flumioxazin and flufenacet. In the field trials, application of preemergence flumioxazin at 125-150 g a.i./ha effectively controlled littleseed canarygrass and several broadleaved weeds, such as toothed dock (Rumex dentatus L.) and bur clover (Medicago denticulata Willd). However, flumioxazin was less effective against a second dominant grass weed, wild oat (Avena ludoviciana Dur.), which infested the field plots. Pendimethalin, which was used in the trials for comparison, at 1000 g a.i./ha, was less effective than flumioxazin in controlling wild oat. Compared with the unweeded control (weedy check) and the plots that received the pendimethalin treatments, the treatments with flumioxazin, at 125-150 g a.i./ha, produced much higher grain yields (i.e., up to 159% and up to 49% increased yield gain, respectively). The highest rate of flumioxazin (250 g a.i./ha) did not increase the weed control achieved, compared with the lower rates, but caused average crop phytotoxicity of 31% at 40 days after the herbicide application or 20 days after the first irrigation. In other field experiments, flufenacet (200-300 g a.i./ha), applied as early post-emergence at 20 days after sowing (one day before the first irrigation), was highly effective in the control of both littleseed canarygrass and wild oat. However, flufenacet was not effective in controlling broad-leaved weeds. Overall, the weed control and the wheat yield obtained with flufenacet 250 g a.i./ha were not significantly different from those obtained with the standard treatment used in the study (i.e., clodinafop, 60 g a.i./ha at 35 days after sowing). In pot bioassay studies, flumioxazin and flufenacet were tested against multiple herbicide-resistant littleseed canarygrass, known to be resistant to acetyl-coA carboxylase (ACCase), acetolactate synthase (ALS) and photosystem II site A (PS-II) inhibitor herbicides, such as clodinafop, sulfosulfuron, and isoproturon, respectively. The results of the pot study indicated effective control (up to 100%) of the herbicide-resistant littleseed canarygrass population by both flumioxazin and flufenacet. Our combined studies of field trials and pot experiment, therefore, indicate that both flumioxazin and flufenacet have the potential to be alternative herbicide options in wheat, particularly for littleseed canarygrass control. As discussed in this paper, while we have demonstrated the potential, further studies are needed, incorporating other agronomic practices in wheat cultivation with flumioxazin and flufenacet, to explore their full potential for the control of multiple herbicide-resistant littleseed canarygrass.

Email

rs_chhokar@yahoo.co.in

Address

ICAR- Indian Institute of Wheat and Barley Research Karnal-132001, India