Fungi as biocontrol agents of weeds: a tropical perspective

1995 ◽  
Vol 73 (S1) ◽  
pp. 58-64 ◽  
Author(s):  
Harry C. Evans
Keyword(s):  
Fungal Pathogens ◽  
Classical Biological Control ◽  
Biocontrol Agents ◽  
Full Potential ◽  
Weed Species ◽  
Conservation Areas ◽  
Weed Biocontrol ◽  
Classical Biocontrol ◽  
Improved Technology

The two approaches, classical and inundative, which can be used to exploit fungi for weed biocontrol, are described and discussed. It is concluded that classical biological control involving the release of coevolved natural enemies, typically highly specific biotrophs into an exotic ecosystem, is the most environmentally and economically acceptable long-term strategy for controlling alien weeds, particularly in conservation areas. Mycoherbicides, based mainly on endemic nectrotrophs, have still not realized their full potential, mainly owing to problems with formulation, application, and market size, but with improved technology these may play an increasingly significant role in agricultural ecosystems. Virulent pathogens with broad host ranges offer the most commercial potential, if these can be tailored to suit individual crop systems. The initial selection of suitable biocontrol agents, based on field, herbarium, and literature surveys is outlined, whilst the problems involved in making the final selection are analysed in detail, especially those relating to taxonomy, biology, and host specificity. Examples are given of fungal pathogens that are being or could be employed for control of some major tropical weed species. Key words: fungi, classical biocontrol, mycoherbicides, tropics, conservation.

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.

scholarly journals Quarantine facilities and legal issues of the use of biocontrol agents in Brazil

2016 ◽  
Vol 51 (5) ◽  
pp. 502-509
Author(s):  
Luiz Alexandre Nogueira de Sá ◽  
Maria Conceição Peres Young Pessoa ◽  
Gilberto José de Moraes ◽  
Jeanne Scardini Marinho-Prado ◽  
Simone de Souza Prado ◽  
...  
Keyword(s):  
Biological Control ◽  
Genetic Material ◽  
Classical Biological Control ◽  
Legal Issues ◽  
Biocontrol Agents ◽  
Classical Biocontrol ◽  
Potential Problems ◽  
Import And Export ◽  
Phytosanitary Measures ◽  
Living Organisms

Abstract: The objective of this work was to address the classical biological control of pests in Brazil, regarding procedures to import and export native biological material. A brief introduction will be given on the current legal issues on the use of biocontrol agents, as well as some considerations on the existing quarantine pests and actions already carried out in the country. The safety in the introduction of exotic organisms is important for Brazilian phytosanitary defense and for a higher adoption of classical biocontrol, making it available for integrated pest management (IPM). Legal and normative aspects establish the procedures that must to be adopted, not only to protect bioprospecting and native organisms, but also to minimize risks to the national genetic patrimony associated with the introduction of exotic organisms. Furthermore, the import/export procedures adopted for vegetal and useful organisms for pest biological control and for other genetic material must be subjected to phytosanitary measures performed in government-certified quarantine facilities and diagnostic laboratories. Finally, the quarantine activities listed here are strategic for safeguarding the country from potential problems arising from border transit of living organisms.

Herbicides as Synergists for Mycoherbicides, and Vice Versa

Weed Science ◽  
2010 ◽  
Vol 58 (3) ◽  
pp. 324-328 ◽  
Author(s):  
Jonathan Gressel
Keyword(s):  
Biocontrol Agents ◽  
Dual Function ◽  
Weed Species ◽  
Callose Synthase ◽  
Calcium Dependent ◽  
Field Level ◽  
Classical Biocontrol ◽  
Species Specific ◽  
Random Screening ◽  
Phosphate Synthase

Except for a small number of cases in which biocontrol agents were introduced from the site of origin of a weed (classical biocontrol), there have been few cases where a pathogen was virulent enough to perform cost effectively in the field as a mycoherbicide. Mycoherbicides are typically weed species specific, so compatibility with herbicides used to control other weeds is often studied. There can be a synergy between mycoherbicides and herbicides at the field level due to overlapping weed spectra (such synergies are not discussed in depth herein). Two approaches have been used to ascertain whether there is synergy in controlling the target weed: (1) random screening with herbicides; (2) using herbicides as antimetabolites to inhibit specific pathways, enhancing virulence. Glyphosate is the most common herbicide to synergize mycoherbicides, possibly due to its dual function as an inhibitor of biosynthesis of phenylpropanoid phytoalexins by suppressing enolphosphate-shikimate phosphate synthase, or by suppressing callose production (by inhibiting callose synthase) as well as inhibiting other calcium-dependent pathways due to the calcium-chelating properties of glyphosate.

Influence of NPK fertilization on weed flora in maize field

2014 ◽  
Vol 63 (1) ◽  
pp. 139-148 ◽  
Author(s):  
Éva Lehoczky ◽  
M. Kamuti ◽  
N. Mazsu ◽  
J. Tamás ◽  
D. Sáringer-Kenyeres ◽  
...  
Keyword(s):  
Plant Nutrition ◽  
Crop Production ◽  
N Availability ◽  
Weed Species ◽  
Negative Effects ◽  
Production Factors ◽  
Maize Field ◽  
Weed Flora ◽  
Npk Fertilization

Plant nutrition is one of the most important intensification factors of crop production. The utilization of nutrients, however, may be modified by a number of production factors, including weed presence. Thus, the knowledge of occurring weed species, their abundance, nutrient and water uptake is extremely important to establish an appropriate basis for the evaluation of their risks or negative effects on crops. That is why investigations were carried out in a long-term fertilization experiment on the influence of different nutrient supplies (Ø, PK, NK, NPK) on weed flora in maize field.The weed surveys recorded similar diversity on the experimental area: the species of A. artemisiifolia, S. halepense and D. stramonium were dominant, but C. album and C. hybridum were also common. These species and H. annuus were the most abundant weeds.Based on the totalized and average data of all treatments, density followed the same tendency in the experimental years. It was the highest in the PK treated and untreated plots, and significantly exceeded the values of NK fertilized areas. Presumably the better N availability promoted the development of nitrophilic weeds, while the mortality of other small species increased.Winter wheat and maize forecrops had no visible influence on the diversity and the intensity of weediness. On the contrary, there were consistent differences in the density of certain weed species in accordance to the applied nutrients. A. artemisiifolia was present in the largest number in the untreated control and PK fertilized plots. The density of S. halepense and H. annuus was also significantly higher in the control areas. The number of their individuals was smaller in those plots where N containing fertilizers were used. Contrary to them, the density of D. stramonium, C. album and C. hybridum was the highest in the NPK treatments.

scholarly journals Leopard Density Estimation within an Enclosed Reserve, Namibia Using Spatially Explicit Capture-Recapture Models

Animals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 724
Author(s):  
Noack ◽  
Heyns ◽  
Rodenwoldt ◽  
Edwards
Keyword(s):  
Management Strategies ◽  
Camera Traps ◽  
Spatially Explicit ◽  
Conservation Areas ◽  
Term Survival ◽  
New Class ◽  
Capture Recapture ◽  
Wildlife Populations ◽  
Effective Conservation

The establishment of enclosed conservation areas are claimed to be the driving force for the long-term survival of wildlife populations. Whilst fencing provides an important tool in conservation, it simultaneously represents a controversial matter as it stops natural migration processes, which could ultimately lead to inbreeding, a decline in genetic diversity and local extinction if not managed correctly. Thus, wildlife residing in enclosed reserves requires effective conservation and management strategies, which are strongly reliant on robust population estimates. Here, we used camera traps combined with the relatively new class of spatially explicit capture-recaptured models (SECR) to produce the first reliable leopard population estimate for an enclosed reserve in Namibia. Leopard density was estimated at 14.51 leopards/100 km2, the highest recorded density in Namibia to date. A combination of high prey abundance, the absence of human persecution and a lack of top-down control are believed to be the main drivers of the recorded high leopard population. Our results add to the growing body of literature which suggests enclosed reserves have the potential to harbour high densities and highlight the importance of such reserves for the survival of threatened species in the future.

Green manure: Alternative to carbon sequestration in a Typic Ustipsamment under semiarid conditions

2018 ◽  
Vol 8 ◽  
Author(s):  
Nelson Virgilio Piraneque Gambasica ◽  
Sonia Esperanza Aguirre Forero ◽  
Adriano Reis Lucheta
Keyword(s):  
Carbon Sequestration ◽  
Cover Crops ◽  
Green Manure ◽  
Block Design ◽  
Climatic Variability ◽  
Plant Cover ◽  
Caribbean Region ◽  
Full Potential ◽  
Semiarid Conditions

Vegetative soil cover mitigates climatic variability and enhances the balance between mineralization and humification processes. Under aerobic conditions, most of the carbon that enters the soil is labile, but a small fraction (1%) is humified and stable, contributing to the soil carbon reserve; therefore, it is important to assess the carbon content captured after green manure cultivation and decomposition. During two consecutive semesters, July to December 2016 and January to June 2017, green manure plots (<em>Zea mays </em>L., <em>Andropogon sorghum </em>subsp.<em> sudanensis </em>and <em>Crotalaria longirostrata</em>) were cultivated individually, in a consortium or amended with palm oil agro-industrial biosolids in a randomized complete block design with 12 treatments. Once decomposed, the different carbon fractions (organic, oxidizable, non-oxidizable, removable and total) were determined. The results showed high total and organic carbon contents under the sorghum treatment, at 30 and 28 Mg ha<sup>-1</sup>, respectively, followed by those under the fallow + biosolid treatment, at 29.8 Mg ha<sup>-1</sup> and 27.5 Mg ha<sup>-1</sup>, respectively. Despite the short experiment duration and the possible contributions of previous management on recalcitrant carbon soil stocks, these findings suggest the importance of maintaining plant cover and utilizing green manure in the Colombian Caribbean region. Long-term experiments may be conducted to confirm the full potential of cover crops on carbon sequestration under tropical semiarid conditions.

scholarly journals Estimating population sizes of lions Panthera leo and spotted hyaenas Crocuta crocuta in Uganda's savannah parks, using lure count methods

Oryx ◽  
2013 ◽  
Vol 48 (3) ◽  
pp. 394-401 ◽  
Author(s):  
Edward Okot Omoya ◽  
Tutilo Mudumba ◽  
Stephen T. Buckland ◽  
Paul Mulondo ◽  
Andrew J. Plumptre
Keyword(s):  
National Parks ◽  
Protected Area ◽  
National Park ◽  
Crocuta Crocuta ◽  
Panthera Leo ◽  
Analysis Method ◽  
Conservation Areas ◽  
Conservation Area ◽  
Population Sizes

AbstractDespite > 60 years of conservation in Uganda's national parks the populations of lions and spotted hyaenas in these areas have never been estimated using a census method. Estimates for some sites have been extrapolated to other protected areas and educated guesses have been made but there has been nothing more definitive. We used a lure count analysis method of call-up counts to estimate populations of the lion Panthera leo and spotted hyaena Crocuta crocuta in the parks where reasonable numbers of these species exist: Queen Elizabeth Protected Area, Murchison Falls Conservation Area and Kidepo Valley National Park. We estimated a total of 408 lions and 324 hyaenas for these three conservation areas. It is unlikely that other conservation areas in Uganda host > 10 lions or > 40 hyaenas. The Queen Elizabeth Protected Area had the largest populations of lions and hyaenas: 140 and 211, respectively. It is estimated that lion numbers have declined by 30% in this protected area since the late 1990s and there are increasing concerns for the long-term viability of both species in Uganda.

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