Plant Pathology Commons^™

Temperature And Inoculum Density As Factors Affecting The Pathogenicity Of Rhizoctonia Solani Kühn On Radish, Paul E. Moser

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The effect of temperature and inoculum density on the incidence of disease on radish caused by Rhizoctonia solani Kühn was studied. The fungus attacks radish at one or more stages during host development and causes pre- and pose-emergence damping-off, root rot, and storage-organ decay. The isolate of the fungus used in the study was obtained from infected radishes grown in Salt Lake County, Utah.

To determine the effect of temperature on the pathogenicity of R. solani on radish, soil temperatures of 15, 20, 25, and 30 C were used. Varying inoculum densities of 1360, 816, 408, 136, and 0 grams …

A Survey Of Verticillium Albo-Atrum From Tomato Fields Of Northern Utah, Jean Redmond Musselman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Verticillium wilt has long been a major disease of tomatoes in Utah. The disease was recognized long before the causal agent was known. In 1932, Dr. H. L. Blood was given the task of investigating a wilt disease that was causing heavy losses to Utah's tomato industry (5). The disease was thought to be caused by Fusarium oxysporum f. lycopersici (Sacc.) Snyder & Hansen. Through his investigations Dr. Blood found Verticillium albo-atrum Reinke and Berthold to be the cause of the disease. He began the laborious task of finding a resistant variety of tomato and transferring the resistance to commercial …

A Cytological Study Of Germinating Aeciospores In The Cronartium Coleosporioides Complex, John A. Christenson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Peridermium harknessii Moore, causal agent of western gall rust, is responsible for deformation, cull and death of pine. In the West it is most serious on lodgepole and ponderosa pines. Seedlings and mature trees may be seriously attacked (Peterson, 1960). Gall rust is easily recognized by its branch galls and trunk cankers. Interest in the disease has fluctuated, but it is considered important enough that government monies support research on the disease in both the United States and Canada.

Studies Of Peronspora Trifoliorum Debary Cause Of Downy Mildew Of Alfalfa, Sheldon B. Waite

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Downy mildew of alfalfa (caused by Peronospora trifoliorum d By) was found to be epidemic on susceptible varieties of alfalfa in northern Utah during 1965. The increase in the amount of downy mildew present was due to the more abundant rainfall and cooler than normal temperatures which prevailed during the summer months of 1965 (Environmental Science Services Administration, 1965). The author observed many of the highly susceptible varieties of alfalfa had 25-30 percent of their leaflets infected with the downy mildew fungus. Because of the epidemic developments of alfalfa downy mildew, an investigation was undertaken to explore the following questions …

Studies On The Relationship Of Polygalacturonase Inhibitors To Verticillium Wilt Resistance In Tomatoes, Robert Lee Sneed

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Early studies of the vascular wilts were directed toward understanding the wilting of susceptible varieties (19, 22, 23). Only in recent years have workers begun to study plant resistance to Fusarium and Verticillium wilts.

A Study Of The Development Of The Sexual Stage Of Rhytisma Punctatum (Pers.) Fries, Ching-Fei Chen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Speckled tar spot caused by Rhytisma punctatum (Persoon) Fries is often found on maples in many parts of the world (Holden, 1961; Koval', 1960; Saccardo, 1889). In Northern Utah it develops every year on leaves of Acer grandidentatum Nutt., and it is especially abundant at elevations above 6,000 feet, where often it is difficult to find even one uninfected leaf. The black speckled spots and the associated leaf coloring tend to add to the brilliance of the autumn colors normally found in the leaves of Bigtooth Maple.

Mechanical Transmission Of A Latent Virus From Apple To Herbaceous Plants, Ali Majid Jafri

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Recent work has shown that viruses are widely disseminated in commercial apple trees growing in this country (1, 14, 16, 17)—quite often one or more latent viruses are found in these plants. Usually latent viruses produce no symptoms, except in special indicator hosts. Latent viruses may cause severe injury when infected plants are grafted to a sensitive variety or rootstock. Actual damage caused by most of the apple viruses is not known but some of these definitely cause serious losses. Experimental plots at Utah State University were ruined by stem pitting virus infection. However, other latent viruses were also present …

Studies And Observations On Potato Powdery Mildew, Brent C. Palmer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Within the past several years, powdery mildew disease has become an increasingly important problem to potato growers in the northern part of Utah. In some fields, reduction in yield due to powdery mildew has been estimated to be as high as 30 percent (Treshow and Cannon, 1961). The disease has been reported from many parts of the world. Other than in Utah, however, the only place where it has been considered to be of economic importance is Palestine. In that country, reduction in yield has been estimated to be as high as 20 percent (Palti and Moeller, 1946).

Studies On Flagging And Root And Butt Rot Of Subalpine Fir, Abies Lasiocarpa (Hook.) Nutt., David Lavar Nelson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Subalpine fir, Abies lasiocarpa (Hook.) Nutt., is a common climax dominant of the extensive spruce-fir forests of the subalpine zone of the Rocky Mountains from the southern Yukon Territory to the high mountains of New Mexico and Arizona (Society of American Foresters, 1954).

Infrared Spectroscopy As Applied To The Study Of Biochemical Changes Induced By Tobacco Mosaic Virus In Leaf Cells, Banavara Krishnappa Chandrasekhar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The biochemical reactions occurring during the early stages in the infection cycle of a plant virus are still unknown. Many studies involving bacteriophage and animal viruses that have been made in recent years have provided evidence of the nature of virus infection, but these have not been of much value in understanding the nature of plant viruses. Infrared spectroscopy applied to the study of viral infection processes by Chochran and his co-workers (1960, 1962) have given some clues about the nature of biochemical changes taking place in the leaf tissues as a result of infection with cucumber mosaic virus and …

Chemical Control Of Spoilage Of Dates, A. Razak Almandil

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Dates are typically a fruit of the subtropical arid regions of the world and are native to the valley of the Euphrates. According to Nixon and Crawford (1936), the earliest records in Iraq (those of the ancient Babylonians and Assyrians) show that their culture was established as early as 3000 B. C.

Basidiomycetes Of The Mount Dellenbaugh Region Of Mohave County, Arizona, Robert Burke Mccomb

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Mount Dellenbaugh is located on the Shivwits Plateau bordering the north rim of the Grand Canyon in Mohave County, Arizona. The elevation of the plateau in the Mount Dellenbaugh area is approximately 6,000 feet. The dominant species comprising the flora of this region are: Pinus ponderosa, Pinus edulis, Juniperus ostiosperma, Quercus gambelli, and Artemisia tredentata.

The Effect Of Certain Fluoride Sprays In The Production Of Soft Suture On Peaches, N. V. Narayanamoorthy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Pollution of the atmosphere and its potential deleterious effects on health, industry, agriculture and natural resources are causing grave concern in many parts of the world. In the past century there has developed in the fields embraced by physical and biological sciences a considerable knowledge of theoretical and applied information, serving as a versatile tool in combating such problems. Air pollution problems seem to have gained much attention with the rapid development of various industries in major parts of the world. Rural and urban areas adjoining these industrial locales are confronted with the dangerous overall problems of air pollution. Evidently, …

Green Rot Of Apricot, Abdul Karim N. Alrayis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This disease, also called jacket rot of apricot, was first though to be similar to a disease caused by a fungus found in central California. The Utah disease was first noted in 1953, in the Henry Hall Chinese apricot orchard at North Ogden. It was not very severe in 1953, but in 1954 and 1955 it affected half of the crop. In 1956 the disease could not be found in the orchard. Infection occurred in young green fruit resulting in brown to black necrotic lesions which varied from 1/4 to 3/4 inches in diameter. Infected fruits usually dropped from the …

The Backcross Method In Breeding Tomatoes Resistant To Fusarium Wilt, Joseph L. Peterson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Many times the plant pathologist and plant breeder are confronted with a plant disease which requires the development of a resistant variety in a limited time. Any breeding program which requires selection from a large population during each segregating generation to insure the right genetic combination will, of course, lengthen the period which it will take to develop this resistant variety. The backcross method of plant breeding, in many cases, helps the plant pathologist and plant breeder develop resistant varieties containing characteristics similar to those of the desired parental type within a shorter period of time.

Red Raspberry Root Rot In Northern Utah, Robert L. Powelson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

During the last few years, red raspberry growers in Utah have been finding that plantings gradually lose vigor and are not profitable. In the largest raspberry growing area in Utah, Utah County, figures taken from the U.S. census from 1930 to 1950, show a decrease in acres of raspberries grown from 401 in 1930 to 190 in 1950 (2). In many instances this deterioration of raspberry plantings in Utah has not been definitely associated with known plant pathogenic fungi or virus infections. Neither can the expansion of suburbs account for this decrease. In certain cases it has been obvious that …

Growth Of The Fungus, Verticillium Albo-Atrum In Resistant And Non-Resistant Strains Of A Tomato Variety And Its Effect On Plant Growth, Robert M. Zundel

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Verticillium wilt, caused by the fungus, Verticillium albo-atrum, is a destructive disease of tomatoes in many areas. Due to the seriousness of this problem, Cannon and Waddoups (1) have developed resistance to this disease in some commercial varieties grown in Utah.

Application Of Paper Electrochromatography To Isolation Of Tobacco Mosaic Virus, Bertram E. Bordewick

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Importance of the problem

The complete study of a virus disease often reaches a stalemate because of failure to isolate the virus itself in a purified form. Methods in current use, such as ultracentrifugation, precipitation, fractionation, and spectroscopic analysis, have in some cases proved successful in virus purification work. Frequently these techniques have not proved satisfactory, particularly with phloem-type viruses which are not mechanically transmitted. This investigation was undertaken to determine the possibility of isolating these and other viruses by electrochromatography.

Studies Of The Dodder Transmission Of The Western-X Virus From Peach To Herbaceous Plants, Lewis G. Weathers

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Western-X disease is considered to be the most serious and destructive virus disease affecting peaches in the northwestern United States. The virus causing this disease in peach also infects chokecherries and most varieties of sweet and sour cherries. There is also evidence (13) that certain varieties of plums and apricots are susceptible. No information now exists to indicate that the virus occurs in plants outside of the genus Prunus. It is found that woody plants such as stone fruit trees are not particularly favorable plants for studying the virus. All attempts to isolate the western-X virus from woody tissue …

The Inheritance Of Resistance To Verticillium Wilt In Tomato, Lester Schaible

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Verticillium wilt of tomatoes is caused by Verticilium albo-atrum and is one of the most destructive diseases of tomatoes in Utah, California, Oregon, and Washington. Control methods thus far devised have proved to be either ineffective or too expensive.

An Etiological And Host Range Study Of Celery Mosaic In Utah, Dennis H. Hall

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Celery mosaic is a virus disease of major economic importance in Utah. In years of severe epiphytotics, it has been a limiting factor in celery production. In 1947 losses due to this disease were estimated to exceed 8 per cent of the total crop. This estimate does not include losses resulting from reduction in grade or from plants discarded in the packing sheds. The celery acreage in Utah dropped from a high of 950 acres in 1946 to 750 acres in 1947 and dropped again in 1948 to 420 acres. Leaders in the industry attributed this reduction in acreage, in …

A Study Of The Physiology Of Grape Roots And Stocks In Relation To A Lime-Induced Chlorosis, Eldrow Reeve

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The word chlorosis comes from the Greek "chloros" meaning light green and is used by plant science workers to designate a disease of plants, the characteristic symptom of which is the yellowing of the leaves.