scholarly journals Principles of Biological Weed Control

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 750D-750
Author(s):  
Susan M. Boyetchko
Keyword(s):  
Biological Control ◽  
Weed Management ◽  
Fungal Pathogens ◽  
The United States ◽  
Reproductive Capacity ◽  
Biological Weed Control ◽  
Weed Biocontrol ◽  
Weed Growth ◽  
Inundative Biological Control ◽  
High Concentrations

Weeds continue to have a tremendous impact on crop yield losses in Canada and the United States, despite efforts to control them with chemicals. Biological control offers an additional means for reducing weed populations while reducing the reliance of the agri-food industry on chemical pesticides. Effective biological strategies that are compatible with good soil conservation practices would benefit farmers while maintaining environmental quality and a sustained production for the future. Inundative biological control of weeds with microbial agents involves the mass production and application of high concentrations of a plant pathogen to a target weed. Historically, biocontrol agents used on weeds have been foliar fungal pathogens. More recently, the soil has become a source for microorganisms, such as rhizobacteria, for development as biological control agents. Several naturally occurring rhizobacteria have weed suppressive properties, where growth and development of weeds such as downy brome, wild oats, leafy spurge, and green foxtail are significantly inhibited. Although the focus in weed biocontrol has been on the eradication of weeds, rhizobacteria may be used to improve seedling establishment of the crop by reducing the weed competition. This can be achieved through a reduction in weed growth, vigor, and reproductive capacity and improvement in the ability of the crop to compete with the weed. Current research in weed biocontrol with microorganisms and its application to weed management systems will be discussed.

Sustainability, conservation tillage and weeds in Canada

1996 ◽  
Vol 76 (4) ◽  
pp. 651-659 ◽  
Author(s):  
D. A. Derksen ◽  
R. E. Blackshaw ◽  
S. M. Boyetchko
Keyword(s):  
Biological Control ◽  
Weed Management ◽  
Conservation Tillage ◽  
The United States ◽  
Integrated Weed Management ◽  
Biological Weed Control ◽  
Plant Residues ◽  
Tillage Systems ◽  
Weed Communities ◽  
Inundative Biological Control

The sustainability of conservation tillage is dependent on the extent of changes in weed community composition, the usage of herbicides, and the development of integrated weed management (IWM) strategies, including biological weed control. The objective of this paper is to review research on conservation tillage and weed management in light of these factors. Recent Canadian research has found that changes in weed communities due to the adoption of conservation tillage are not necessarily those expected and were not consistant by species, location, or year. Changes reflected the use of different selection pressures, such as different crop rotations and herbicides, within the studies to a greater extent than weed life cycle groupings. Therefore, research that determines the reasons for change or the lack of change in weed communities is required to provide the scientific basis for the development of IWM strategies. Documented herbicide usage in conservation tillage varies from less than to more than conventional-tillage systems. Potential to reduce herbicide usage in conservation-tillage systems exists. Furthermore, the herbicides used in western Canada are different from those causing ground water contamination in the United States, are less volatile, and are used at lower rates. The presence of surface crop residues in conservation tillage may provide a unique environment for classical and inundative biological control agents. Some insects, fungi, and bacteria have the potential to survive to a greater extent in undisturbed plant residues. Residue management and conservation tillage systems are evolving in Canada. Research must keep pace by providing weed management strategies that enchance the sustainability of these systems. Key words: Biological control, zero tillage, integrated weed management, residues, herbicides, rhizobacteria.

scholarly journals Impact of soil microorganisms on weed biology and ecology

2005 ◽  
Vol 77 (1) ◽  
pp. 41-56 ◽  
Author(s):  
S.M. Boyetchko
Keyword(s):  
Biological Control ◽  
Weed Management ◽  
Mycorrhizal Fungi ◽  
Soil Microorganisms ◽  
Arbuscular Mycorrhizal ◽  
Management Tool ◽  
Mycorrhizal Dependency ◽  
Cultural Methods ◽  
Weed Growth ◽  
Inundative Biological Control

While weed populations have traditionally been controlled by chemical and cultural methods, inundative biological control with microbial agents offers an additional strategy for managing weeds. Foliar pathogens have long been sought after as potential biocontrol agents, but rhizosphere microorganisms and their influence on weed growth and development have been ignored until recently. Rhizosphere soil is replete with a variety of microorganisms such as rhizobacteria, pathogenic soil-borne fungi, and arbuscular mycorrhizal fungi, all of which have a direct or indirect impact on weeds and their competitive ability. In some cases, specific microbes have a detrimental effect on the weeds and can be exploited as biological control agents. The ubiquitous mycorrhizal fungi are beneficial symbionts that can impart a competitive ad vantage to their plant hosts, particularly if mycorrhizal dependency is exhibited in weeds as opposed to crops. It may be possible to exploit various soil microbes by directly or indirectly reducing weed competition and tipping the competitive advantage in favor of the crop. However, information available on microbial/weed/crop relationships is limited and research efforts are required to explore the use of soil microorganisms as another weed management tool.

Contrasting research approaches to managing mistletoes in commercial forests and wooded pasturesThis minireview is one of a collection of papers based on a presentation from the Stem and Shoot Fungal Pathogens and Parasitic Plants: the Values of Biological Diversity session of the XXII International Union of Forestry Research Organization World Congress meeting held in Brisbane, Queensland, Australia, in 2005.

Botany ◽  
2009 ◽  
Vol 87 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Nick Reid ◽  
Simon F. Shamoun
Keyword(s):  
Biological Control ◽  
Fungal Pathogens ◽  
Biological Diversity ◽  
Management Strategies ◽  
Biodiversity Loss ◽  
Classical Biological Control ◽  
Dwarf Mistletoe ◽  
Silvicultural Treatments ◽  
Inundative Biological Control

Many mistletoe species are pests in agricultural and forest ecosystems throughout the world. Mistletoes are unusual “weeds” as they are generally endemic to areas where they achieve pest status and, therefore, classical biological control and broad-scale herbicidal control are usually impractical. In North American coniferous forests, dwarf mistletoe ( Arceuthobium spp.) infection results in major commercial losses and poses a public liability in recreation settings. Hyperparasitic fungi have potential as biological control agents of dwarf mistletoe, including species which attack shoots, berries, and the endophytic systems of dwarf mistletoe. Development of an inundative biological control strategy will be useful in situations where traditional silvicultural control is impractical or undesirable. In southern Australia, farm eucalypts are often attacked and killed by mistletoes ( Amyema spp.) in grazed landscapes where tree decline and biodiversity loss are major forms of land degradation. Although long-term strategies to achieve a balance between mistletoe and host abundance are promoted, many graziers want short-term options to treat severely infected trees. Recent research has revisited the efficiency and efficacy of silvicultural treatments and selective herbicides in appropriate situations. The results of recent research on these diverse management strategies in North America and Australia are summarized.

Differential Susceptibility of Bagrada hilaris (Hemiptera: Pentatomidae) to Different Species of Fungal Pathogens

2019 ◽  
Author(s):  
Anahi A Barrera-López ◽  
Ariel W Guzmán-Franco ◽  
Materesa Santillán-Galicia ◽  
Fernando Tamayo-Mejía ◽  
Rafael Bujanos-Muñiz ◽  
...  
Keyword(s):  
Biological Control ◽  
Fungal Pathogens ◽  
Microbial Control ◽  
Differential Susceptibility ◽  
Field Studies ◽  
The United States ◽  
Fungal Species ◽  
Biological Control Agents ◽  
Percent Mortality ◽  
Microbial Agents

Abstract Bagrada hilaris Burmeister (Hemiptera: Pentatomidae) is a pest of Palearctic origin. Its presence in the United States was first reported in 2008 and in Mexico in 2014; it affects brassica crops. There are practically no reports of natural enemies of B. hilaris in America. Entomopathogenic fungi are strong candidates for microbial control of this pest. Evaluating the susceptibility of this pest to fungi that are native to the region where they will be used is a sensible first step to finding candidate biological control agents. The aim of our research was to select potential microbial agents to control B. hilaris. Eleven isolates of Beauveria bassiana, Beauveria pseudobassiana, Metarhizium anisopliae, and Isaria fumosorosea were evaluated to determine the susceptibility of B. hilaris. Isolates of B. bassiana caused the highest mortality due to infection (100%) compared with the other isolates. The I. fumosorosea isolate caused the lowest percent mortality (56%). The two B. bassiana isolates Bb88 and AP3 were more virulent than M. anisopliae isolate Ma129. The sex of the insect had no effect on infection levels achieved by B. bassiana isolates Bb88 and AP3. The results of our study contribute valuable information for the development of fungal species with potential to manage B. hilaris populations. Field studies are the next step in order to develop these isolates as biological control agents of B. hilaris.

Successes We May Not Have Had: A Retrospective Analysis of Selected Weed Biological Control Agents in the United States

2014 ◽  
Vol 7 (4) ◽  
pp. 565-579 ◽  
Author(s):  
Hariet L. Hinz ◽  
Mark Schwarzländer ◽  
André Gassmann ◽  
Robert S. Bourchier
Keyword(s):  
United States ◽  
Biological Control ◽  
Host Range ◽  
Evaluation Process ◽  
The United States ◽  
Biocontrol Agents ◽  
Biological Weed Control ◽  
Range Data ◽  
Weed Biological Control ◽  
Threatened And Endangered Species

AbstractIn this paper, we describe five successful classical biological weed control agents released in the United States. For each of the five arthropod species, we compared data from prerelease studies that experimentally predicted the agent's host range with data collected postrelease. In general, experimental host range data accurately predicted or overestimated risks to nontarget plants. We compare the five cases with insects recently denied for introduction in the United States and conclude that none of the discussed agents would likely be approved if they were petitioned today. Three agents would be rejected because they potentially could attack economic plants, and two because of potential attack on threatened or endangered plants. All five biocontrol agents have contributed significantly to the successful management of major weeds with no or minimal environmental risk. We believe that the United States may miss opportunities for sustainable and environmentally benign management of weeds using biological control if the regulatory framework only considers the risks of agents as potential plant pests and treats any host-range data regarding economic or threatened and endangered species as a binary decision (i.e., mandates rejection if there is any chance of feeding or development). As a way forward we propose the following: (1) the addition of risk and benefit analyses at the habitat level with a clear ranking of decision-making criteria as part of the U.S. Department of Agriculture Animal and Plant Health Inspection Service Technical Advisory Group's evaluation process of biocontrol agents; (2) recognition of the primacy of realized host range data for potential agents that considers the insect's host selection behavior instead of emphasizing fundamental host range data during release evaluations, and (3) development of formalized postrelease monitoring of target and nontarget species as part of the release permit. These recommendations may initially be advanced through reassessment of current policies but may in the longer term require the implementation of dedicated biocontrol legislation.

Biological control of air-borne pathogens

1988 ◽  
Vol 318 (1189) ◽  
pp. 265-281 ◽  
Keyword(s):  
Biological Control ◽  
Fungal Pathogens ◽  
Population Level ◽  
Reproductive Capacity ◽  
Forest Trees ◽  
Subsequent Growth ◽  
Field Crops ◽  
Direct Penetration ◽  
Successful Control ◽  
Biological Methods

Some pathogens are partly controlled by microorganisms that occur naturally on aerial surfaces of plants, and many attempts have been made to improve control by applying selected antagonists to such surfaces. Antagonists often compete for nutrients with the pathogen, and antibiotics may be formed that reduce germination of its spores and subsequent growth. Hyphae of fungal pathogens may be killed on contact with the antagonist or by direct penetration. The plant’s defences may be stimulated before challenge by a pathogen. Apart from killing the pathogen, an antagonist may reduce its reproductive capacity. The examples given illustrate the operation of these different mechanisms in the control of a wide variety of diseases. For diseases of foliage, flowers or fruit, glasshouse crops offer more attractive possibilities for control than field crops because the population level of antagonists is easier to maintain. In some cases plants can be protected by inoculation before transplanting them to the field. Foliage and canker diseases of forest trees present problems too intractable for successful control, but in orchards the prospects are better; for example, methods are available for combining pruning with application of inoculum. Similarly, in some circumstances tree stumps can be inoculated to prevent colonization by a pathogen. Where biological methods are as effective as chemical ones and comparable in cost, they are to be preferred on environmental grounds. In some cases they can be combined with advantage; for example a lower concentration of fungicide may suffice if applied with an antagonist.

scholarly journals Ventenata dubia’s native range and consideration of plant pathogens for biological control

2019 ◽  
Vol 12 (4) ◽  
pp. 242-245 ◽  
Author(s):  
Maryam Alomran ◽  
George Newcombe ◽  
Timothy Prather
Keyword(s):  
Biological Control ◽  
North America ◽  
North Africa ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Relevant Literature ◽  
The United States ◽  
Herbarium Specimens ◽  
Native Range ◽  
Western Asia

AbstractVentenata [Ventenata dubia (Leers) Coss.] is a nonindigenous, invasive grass in the inland Pacific Northwest (PNW) of the United States. It appears to be present in the PNW without any evidence of disease expression. Surveys of V. dubia in the PNW (Idaho, Montana, Oregon, and Washington) were entirely negative for fungi, including types of pathogens that might be expected in grasses (e.g., rust, powdery mildew, choke). In Europe, where V. dubia is native, fungi were documented (i.e., Septoria ventenatae Sandu, Tilletia fusca Ellis & Everh., and Tilletia elisabethae T. Denchev & Denchev) on V. dubia. In its native range there likely are natural enemies that may limit V. dubia abundance, and these may include fungal pathogens. Pathogens of V. dubia from its native range may hold potential for use as classical biological control agents in North America, and if deemed safe, could be introduced. To ascertain V. dubia’s native range, we compiled data from herbarium specimens, consulted with herbarium curators in the region, and searched relevant literature. We found that V. dubia primarily is reported in southern Europe and western Asia. Ventenata dubia has been reported only occasionally from North Africa in Algeria and Morocco. The common name “North Africa grass” likely originated from references to V. dubia in the 19th-century botanical explorations in Algeria of the French botanist, Ernest Cosson, who published the current scientific name based on a preexisting name in 1854. Another finding of interest is that the latitudinal range of collections from Europe and North Africa of V. dubia spans Tunisia to Finland. The plant may thus be adapted to a range of environments, indicating it could become more widely distributed in North America. Efforts to search its native range for pathogens should also consider the range of environmental conditions found within its native and introduced ranges.

scholarly journals Rhizobacteria as Biocontrol Agents of Weeds

1996 ◽  
Vol 10 (3) ◽  
pp. 601-609 ◽  
Author(s):  
Robert J. Kremer ◽  
Ann C. Kennedy
Keyword(s):  
Biological Control ◽  
Weed Control ◽  
Weed Management ◽  
Management Practices ◽  
Field Studies ◽  
Biocontrol Agents ◽  
Residue Management ◽  
Weed Growth ◽  
Deleterious Rhizobacteria ◽  
Herbicide Use

There is a current need to develop alternative weed management techniques in response to demands for reduction in herbicide use due mainly to health and environmental concerns. Therefore, all possible nonchemical strategies for weed control should be considered, including biological control. Deleterious rhizobacteria (DRB), largely overlooked as potential biological control agents for weeds until recently, are able to colonize root surfaces of weed seedlings and suppress plant growth. Limited field studies indicate that DRB suppressed weed growth, and reduced weed density, biomass, and seed production. In this manner, crops out-compete the suppressed weeds for growth requirements, eliminating the necessity for eradication of weeds in the crop. Establishment of DRB as a viable biological control strategy initially will require integration with other weed control approaches including other biocontrol agents, agrichemicals, and cultural and residue management practices. To achieve success, more in-depth research is needed on ecology of bacteria-plant relationships, mechanisms of action (including characterization of phytotoxins), inocula formulations, and methods to enhance crop competition.

Biological Control and Its Integration in Weed Management Systems for Purple and Yellow Nutsedge (Cyperus rotundusandC. esculentus)

1987 ◽  
Vol 1 (1) ◽  
pp. 84-91 ◽  
Author(s):  
Sharad C. Phatak ◽  
M. Brett Callaway ◽  
Charles S. Vavrina
Keyword(s):  
United States ◽  
Biological Control ◽  
Weed Management ◽  
The United States ◽  
Management Systems ◽  
Biological Control Of Weeds ◽  
Yellow Nutsedge ◽  
Living Organisms ◽  
Vast Area ◽  
Classical Strategy

Observations of the effects of living organisms on weeds dates from 1795 when an insect,Dactylopius ceylonicus, was introduced for drooping pricklypear (Opuntia vulgarisMiller) control over a vast area. Since that time, biological control of weeds employed mainly the classical strategy of introducing natural enemies from areas of co-evolution. Self-perpetuation and dissemination of these introduced enemies was essential to suppress successfully the weed below economic levels. This classical tactic is suited particularly for weeds that are distributed widely in less intensively cropped or noncropped areas. Guidelines to introduce foreign organisms for biological control of weeds in the United States have been established.

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