scholarly journals Hormesis: Biphasic Dose-Responses to Fungicides in Plant Pathogens and Their Potential Threat to Agriculture

10.5772/55359 ◽  
2013 ◽  
Author(s):  
Carla D. ◽  
Francisco J.
Keyword(s):  
Plant Pathogens ◽  
Potential Threat ◽  
Dose Responses

Evaluating the Threat Posed by Fungi on the APHIS List of Regulated Plant Pests

2006 ◽  
Vol 7 (1) ◽  
pp. 61 ◽  
Author(s):  
Amy Y. Rossman ◽  
Kerry Britton ◽  
Doug Luster ◽  
Mary Palm ◽  
Matthew H. Royer ◽  
...  
Keyword(s):  
Geographic Distribution ◽  
Plant Pathogens ◽  
Economic Value ◽  
The United States ◽  
Potential Threat ◽  
Plant Host ◽  
Plant Pests ◽  
Terrestrial Arthropods ◽  
Plant Pest ◽  
Scientific Name

An evaluation of the potential threat of fungi on the APHIS Regulated Plant Pest List was conducted by the federal interagency Invasive Terrestrial Arthropods and Pathogens (ITAP) Subcommittee on Plant Pathogens. Each species was evaluated based on the importance of the plant host, geographic distribution, and state of knowledge. Fungi that cause serious diseases of plants of major economic value and forest trees were considered a threat if the fungus does not occur in the United States. Drs. Erica Cline and David Farr recently reviewed the fungi on the APHIS Regulated Plant Pest List, providing an accurate scientific name as well as the disease, plant hosts, and geographic distribution for each species. Accepted for publication 3 May 2006. Published 5 May 2006.

Biological control of soilborne plant pathogens

1988 ◽  
Vol 3 (2-3) ◽  
pp. 98-101 ◽  
Author(s):  
Robert D. Lumsden ◽  
George C. Papavizas
Keyword(s):  
Biological Control ◽  
Plant Pathogens ◽  
Sclerotium Rolfsii ◽  
Control Measures ◽  
Economic Losses ◽  
Potential Threat ◽  
Private Industry ◽  
Soilborne Plant Pathogens ◽  
Fungal Plant Pathogens ◽  
Talaromyces Flavus

AbstractSoilborne plant pathogens cause major economic losses in agricultural crops, and the present methods for control of diseases brought about by these pathogens are inadequate. Alternatives are also needed to substitute for the use of chemical fungicides. Many of these are known to induce tumors in experimental animals and are thus regarded by some investigators as potential human carcinogens when present as residues in food and water. In addition, such alternative control measures are needed because of the potential threat of development of resistance to fungicides, especially systemic fungicides, by fungal plant pathogens, and because of nontarget side effects on other plant pathogens and on beneficial microorganisms. Alternative disease control is sometimes possible through development of crop plants resistant to disease. Unfortunately, however, resistance is lacking or not available for many diseases caused by soilborne plant pathogens. Another biological means of controlling disease which is presently gaining much attention is biological control. Several systems of biological control are presently being explored and may be developed in a few years into reliable alternatives to conventional chemical control methods. The use of the mycoparasite Sporidesmium sclerotivorum, for example, against several diseases caused by Sclerotinia species is promising. Talaromyces flavus may in the future be exploited for use against several wilt diseases caused by Verticillium dahliae. Finally, practical control of several diseases caused by Pythium spp., Rhizoctonia solani, and Sclerotium rolfsii may eventually become possible through the use of Trichoderma spp. and Gliocladium virens. Development of these biological control systems will require much additional research directed toward a better understanding of the basic biology and mechanisms of action of beneficial fungi against plant pathogens. In addition, extensive cooperation will be required among research scientists, governmental agencies responsible for regulating the use of pestcontrol systems, and most importantly, private industry to develop biological control agents for the market and to coordinate acceptance and use by producers and acceptance by consumers.

scholarly journals First Inventory of Fungi in Symptomless and Symptomatic Chinese Mesona Indicates Phytopathological Threat

Plant Disease ◽  
2020 ◽  
Vol 104 (9) ◽  
pp. 2391-2397
Author(s):  
Chung-Wei Hsieh ◽  
Ying-Ying Chuang ◽  
Ming-Zhe Lee ◽  
Roland Kirschner
Keyword(s):  
Plant Pathogens ◽  
Sequence Data ◽  
Elongation Factor ◽  
Botanical Garden ◽  
Common Species ◽  
Leaf Spot Disease ◽  
Cultivation Condition ◽  
Potential Threat ◽  
Internal Transcribed Spacer Region ◽  
Leaf Spots

Chinese mesona (Platostoma palustre) plays an important role as special crop in Southeast Asia and Taiwan for the production of herbal tea, grass jelly, and further processed food. In order to assess the potential threat of fungi to Chinese mesona, we surveyed isolates from symptomless plants in the area of mesona production, as well as from leaf spots of potted plants in a garden shop and a plantation in a botanical garden in Taiwan. From leaves, stems, and roots of 15 symptomless plants sampled at five collection events over two years, 154 isolates from 810 surface-sterilized plant fragments were obtained and identified based on DNA sequence data of the internal transcribed spacer region, and partially of the β-tubulin and histone H3 genes. The most common species belonged to the genera Cercospora, Colletotrichum, and Fusarium and were considered to be potential plant pathogens. Latent pathogenicity was confirmed by an infection experiment with an endophytic strain of Corynespora cassiicola. Observation of leaf spot disease associated with Cercospora kikuchii suggested pathogenicity of this fungus, which was also isolated as an endophyte from symptomless leaves. We hypothesize that the most common endophytic fungi are latent pathogens in the host and may cause plant disease when the host becomes weakened by senescence or changed cultivation condition. Leaf spots of plants in the botanical garden were associated with a species of Pseudocercospora, which was not found among the endophytic isolates and is newly described based on morphology and analysis of translation elongation factor 1 alpha gene sequences.

scholarly journals Screening potential insect vectors in a museum biorepository reveals undiscovered diversity of plant pathogens in natural areas

2021 ◽  
Author(s):  
Valeria Trivellone ◽  
Wei Wei ◽  
Luisa Filippin ◽  
Christopher Dietrich
Keyword(s):  
Plant Pathogens ◽  
Insect Vectors ◽  
Natural Areas ◽  
Potential Threat ◽  
Natural Habitats ◽  
Pcr Screening ◽  
New Associations ◽  
Vector Borne ◽  
Phloem Feeding ◽  
Untapped Resource

Phytoplasmas (Mollicutes, Acholeplasmataceae), vector-borne obligate bacterial plant-parasites, infect nearly 1,000 plant species and unknown numbers of insects, mainly leafhoppers (Hemiptera, Deltocephalinae), which play a key role in transmission and epidemiology. Although the plant-phytoplasma-insect association has been evolving for >300 million years, nearly all known phytoplasmas have been discovered as a result of the damage inflicted by phytoplasma diseases on crops. Few efforts have been made to study phytoplasmas occurring in non-economically important plants in natural habitats. In this study, a sub-sample of leafhopper specimens preserved in a large museum biorepository was analyzed to unveil potential new associations. PCR screening for phytoplasmas performed on 227 phloem-feeding leafhoppers collected worldwide from natural habitats revealed the presence of 6 different previously unknown phytoplasma strains. This indicates that museum collections of herbivorous insects represent a rich and largely untapped resource for discovery of new plant pathogens, that natural areas worldwide harbor a diverse but largely undiscovered diversity of phytoplasmas and potential insect vectors, and that independent epidemiological cycles occur in such habitats, posing a potential threat of disease spillover into agricultural systems. Larger-scale future investigations will contribute to a better understanding of phytoplasma genetic diversity, insect host range, and insect-borne phytoplasma transmission and provide an early warning for the emergence of new phytoplasma diseases across global agroecosystems.

Freeze substitution fixation of fungal reproductive structures and spores

1989 ◽  
Vol 47 ◽  
pp. 990-991
Author(s):  
C. W. Mims ◽  
E. A. Richardson
Keyword(s):  
Plant Pathogens ◽  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Chemical Fixation ◽  
Dialysis Membrane ◽  
Razor Blade ◽  
Thin Sections ◽  
Reproductive Structures ◽  
Dry Down ◽  
Diamond Knife

The advantages of freeze substitution fixation over conventional chemical fixation for preservation of ultrastructural details in fungi have been discussed by various authors. As most ascomycetes, basidiomycetes and deuteromycetes do not fix well using conventional chemical fixation protocols, freeze substitution has attracted the attention of many individuals interested in fungal ultrastructure. Thus far most workers using this technique on fungi have concentrated on thin walled somatic hyphae. However, in our laboratory we have experimented with the use of freeze substitution on a variety of fungal reproductive structures and spores with promising results.Here we present data on freeze substituted samples of sporangia of the zygomycete Umbellopsis vinacea, basidia of Exobasidium camelliae var. gracilis, developing teliospores of the smut Sporisorium sorghi, germinating teliospores of the rust Gymnosporangium clavipes, germinating conidia of the deuteromycete Cercosporidium personatum, and developing ascospores of Ascodesmis nigricans.Spores of G. clavipes and C. personatum were deposited on moist pieces of sterile dialysis membrane where they hydrated and germinated. Asci of A. nigricans developed on pieces of dialysis membrane lying on nutrient agar plates. U. vinacea was cultured on small pieces of agar-coated wire. In the plant pathogens E. camelliae var. gracilis and S. sorghi, a razor blade was used to remove smal1 pieces of infected host issue. All samples were plunged directly into liquid propane and processed for study according to Hoch.l Samples on dialysis membrane were flat embedded. Serial thin sections were cut using a diamond knife, collected on slot grids, and allowed to dry down onto Formvar coated aluminum racks. Sections were post stained with uranyl acetate and lead citrate.

Effect of Homeopathic Preparations on Lettuce, Parasitized or Not by Meloidogyne enterolobii

Homeopathy ◽  
2020 ◽  
Author(s):  
Thais Moraes Ferreira ◽  
Mariana Zandomênico Mangeiro ◽  
Alexandre Macedo Almeida ◽  
Ricardo Moreira Souza
Keyword(s):  
Plant Pathogens ◽  
Nematode Control ◽  
Plant Tolerance ◽  
Nematode Reproduction ◽  
Meloidogyne Enterolobii ◽  
Negative Effect ◽  
Meloidogyne Spp ◽  
Constant Dose ◽  
Lettuce Growth ◽  
Complementary Strategy

Abstract Background There are relatively few scientific works on the use of homeopathy to manage plant pathogens, particularly nematodes. A handful of studies focused on Meloidogyne spp. parasitizing vegetables have brought contradictory results on nematode control and enhancement of plant tolerance to parasitism. Objective Our goal was to assess the effect of Cina—a well-known anti-nematode ingredient—on Meloidogyne enterolobii parasitizing lettuce. Methods Cina was applied daily on nematode-inoculated plants, from the seedling stage until harvest. We tested an evenly spaced range of Hahnemannian concentrations (c), which were applied though irrigation with a constant dose of the ingredient. Several absolute and relative controls were employed to allow the assessment of the effect of Cina on nematode reproduction and lettuce growth. Results Cina affected growth of non-parasitized plants, both positively and negatively; this effect was modulated by the c applied and the thermal stress suffered by the plants in one of the assays. The effect of Cina on the growth of nematode-parasitized plants was neutral or negative. Cina reduced nematode reproduction by 25–36%. Conclusion Based on the moderate negative effect of Cina on M. enterolobii reproduction, it seems this ingredient may be useful as a complementary strategy for Meloidogyne control. But Cina did not enhance the tolerance of lettuce to Meloidogyne spp.

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