Plant Pathology Commons^™

Weber-Fechner Law, Forrest W. Nutter Jr.

Plant Pathology and Microbiology Publications

Several models have been proposed in the field of psychophysics to quantify relationships between any stimulus (e.g., touch, sound, light, and smell) and the perceived response by individuals. One such model is referred to as the Weber-Fechner Law. The Weber −Fechner Law, however, is not one law, but two separate laws: Weber's Law and Fechner's Law. Moreover, not all human senses respond to stimuli according to Fechner's law (in fact many do not). Weber's Law and special cases such as Fechner's Law are each based on the “just noticeable difference threshold” concept.

A Brief History Of Corn: Looking Back To Move Forward, Jon Derek Pruitt

Doctoral Documents from Doctor of Plant Health Program

Maize was domesticated from teosinte in Mexico some 7,000 to 10,000 years ago and quickly spread through the Americas. It has become one of the most important crops at a local and global level. Two types, Northern Flint corn and Southern Dent corns provided the basis of the genetic background of modern maize hybrids. The development of hybrids, first double-cross and later single-cross hybrids, along with a transition to high input farming provided huge yield increases, which have continued to improve with improving technology.

Increase in maize production also caused a rise in Western corn Rootworm (Diabrotica virgifera ...

Loquat Diseases : Black Spot And Fleck, R F. Doepel

Journal of the Department of Agriculture, Western Australia, Series 4

Black spot is common on loquats and renders affected fruit unmarketable.

Another disfiguring fungal disease, fleck, has also become established in this State.

The newer fungicide dodine is recommended for controlling both these diseases.

An Overview Of Plant Defenses Against Pathogens And Herbivores, Brian C. Freeman, Gwyn A. Beattie

Plant Pathology and Microbiology Publications

Plants represent a rich source of nutrients for many organisms including bacteria, fungi, protists, insects, and vertebrates. Although lacking an immune system comparable to animals, plants have developed a stunning array of structural, chemical, and protein-based defenses designed to detect invading organisms and stop them before they are able to cause extensive damage. Humans depend almost exclusively on plants for food, and plants provide many important non-food products including wood, dyes, textiles, medicines, cosmetics, soaps, rubber, plastics, inks, and industrial chemicals. Understanding how plants defend themselves from pathogens and herbivores is essential in order to protect our food supply and ...

Does Seed Size Affect The Rate Of Germination And Early Seedling Growth In Hairy Vetch?, Joy Ekpo

McCabe Thesis Collection

Size is an important characteristic of seed quality because larger seeds with larger volume contain more resources and are likely to exhibit greater vigor than smaller seeds (Ellis, 1992). In a range of plant species, seed size has been shown to affect germination rate, emergence rate, success of establishment, and growth (Black 1957; Bentley et al. 1980; Sanderson et al. 2002). Hairy vetch is an annual legume that is used for improvement of soil for pasture and to provide ground cover protecting against erosion (Duke 1981; Undersander 2002; Sattell et al 1988). Problems facing the establishment of hairy vetch are ...

Vegetable Diseases Of Utah, Claudia Nischwitz, Mair Murray, Nick Volesky

All Current Publications

This guide provides a list of vegetable crop diseases that have been documented in Utah along with some that are likely to occur. Plant diseases are caused by pathogens such as fungi, bacteria, viruses, and fungal-like organisms. Diagnosing specific plant diseases takes careful observation of signs, symptoms, and sometimes culturing and molecular testing in a laboratory setting.

The Genetic And Molecular Basis Of Plant Resistance To Pathogens, Yan Zhang, Thomas Lubberstedt, Mingliang Xu

Agronomy Publications

Plant pathogens have evolved numerous strategies to obtain nutritive materials from their host, and plants in turn have evolved the preformed physical and chemical barriers as well as sophisticated two-tiered immune system to combat pathogen attacks. Genetically, plant resistance to pathogens can be divided into qualitative and quantitative disease resistance, conditioned by major gene(s) and multiple genes with minor effects, respectively. Qualitative disease resistance has been mostly detected in plant defense against biotrophic pathogens, whereas quantitative disease resistance is involved in defense response to all plant pathogens, from biotrophs, hemibiotrophs to necrotrophs. Plant resistance is achieved through interception of ...

Fungicides: Triazoles, Daren S. Mueller

Integrated Crop Management News

The fungicide group, demethylation inhibitors (DMI), which contain the triazole fungicides, was introduced in the mid-1970s. Triazoles consist of numerous members, of which several are labeled or are in the process of being labeled for use on field crops in Iowa--cyproconazole, flusilazole, flutriafol, metconazole, myclobutanil, propiconazole, prothioconazole, tebuconazole, and tetraconazole.

Detection And Measurement Of Plant Disease Symptoms Using Visible-Wavelength Photography And Image Analysis, Clive H. Bock, Forrest W. Nutter Jr.

Plant Pathology and Microbiology Publications

Plant disease detection and severity assessment are required for many purposes, including predicting yield loss, monitoring and forecasting epidemics, judging host resistance and for studying fundamental biological host–pathogen processes. If assessments of disease severity are inaccurate and/or imprecise, incorrect conclusions might be drawn and incorrect actions taken. Image analysis based on digital images made using visible wavelengths is one of the several methods used to detect and quantify disease; it offers advantages compared with visual assessment or other methods. Over the last 30 years, major advances have been made to improve reliability, precision and accuracy of image analysis ...

Importance Of Myxomycetes In Biological Research And Teaching, Harold W. Keller, Sydney E. Everhart

Papers in Plant Pathology

Myxomycetes, the true slime molds, are highlighted in research and teaching that emphasizes various stages of the life cycle as experimental models. Past and current phylogenetic classifications of Myxomycetes on the tree of life are presented. Life cycle stages are illustrated, described, and discussed. Simple laboratory demonstrations and experiments are described that include spore germination, spore release, and moist chamber cultures utilizing organic matter from various microhabitats. Novel compounds isolated from fruiting bodies and plasmodia of 22 myxomycete species are tabulated, some of which exhibit biological activity that function as antibiotics, antimicrobials, and are cytotoxic to cancer cells. Aeroallergens include ...