Plant Pathology Commons^™

A Study Of The Environmental Conditions Influencing The Development Of Stem Rust In The Absence Of An Alternate Host. Iii. Further Studies Of The Viability Of Urediniospores Of Puccinia Graminis Tritici, George L. Peltier

Nebraska Agricultural Experiment Station: Historical Research Bulletins

1. The influence of relative humidity and temperature on the viability of the urediniospores of two Physiologic Forms of Puccinia graminis tritici has been determined. 2. The same general relation between the viability of the urediniospores and the relative humidity and temperature was found, namely, that the lower the temperature the longer the spores retained their viability at all relative humidities, while at any stated temperature the spores were viable the longest at the medium humidities. 3. Urediniospores of Physiologic Form XXI held at 49.0 per cent relative humidity and maintained at a temperature of 5° C. when tested for …

Further Studies On The Effect Of Environment On Potato Degeneration Diseases, R. W. Goss, George L. Peltier

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The identification of potato degeneration diseases in the field is extremely difficult owing to the number of diseases now described, their manifestation on different varieties, the combination of several diseases on the same plant, and the further splitting up of these combinations into separate diseases. The influence of environmental factors in intensifying or inhibiting the symptoms of these diseases also increases the difficulty of diagnosis. In the present investigation the effect of environmental factors has been studied with the purpose of determining the limiting factor or factors in the masking of the symptoms, in the hopes of simplifying a complex …

Control Equipment For The Study Of The Relation Of Environment To Disease, George L. Peltier, R. W. Goss

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The investigation of certain plant disease problems in Nebraska has necessitated the study of the relation of various environmental factors to these diseases. The control of these environmental factors in the greenhouse studies has been obtained by the use of previously described apparatus or their modification and adaptation, along with new methods which have been devised to meet the needs of these investigations. In view of the widespread interest in the subject of environmental control for experimental studies, it was deemed advisable to present briefly the methods now in use in this department in the hope that the information may …

Potato Wilt And Stem-End Rot Caused By Fusarium Eumartii, R. W. Goss

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The present study was undertaken to obtain more information regarding the pathogenicity of Fusarium eumartii and to compare its action with F. oxysporum, in order to distinguish between and to determine the relative importance of the diseases produced by these two organisms. An effort was also made to explain the many negative results of isolation studies reported by various investigators, as well as the inconsistent results often reported in studies of the transmission of wilt by infected tubers. Investigations dealing with the effect of certain environmental conditions on the occurrence of the disease were also undertaken. All of the …

Effect Of Environment On Potato Degeneration Diseases, R. W. Goss

Nebraska Agricultural Experiment Station: Historical Research Bulletins

During recent years much of the investigational work on the degeneration diseases of the potato has been directed toward the separation and identification of a number of diseases formerly grouped under the general names of mosaic, leaf roll, and "running out". Extensive studies have also been made on methods of transmission, host range, overwintering and the identification of the evasive causal factor. Investigations of this type, however, have progressed slowly because of the necessity of developing new methods of research, because of the complexity of the problem, and because of the lack of knowledge regarding the causal factors. Meanwhile there …

Bulletin 119 - Take-All Of Wheat And Similar Diseases Of Cereals, W. M. Carne, J. G.C. Campbell

Bulletins 1 - 2999

This important disease, known also as Footrot, Blackleg, and Whiteheads, affects wheat principally, but also occurs on barley, rye, and certain grasses. In a very few instances it has been known to attack oats, but this is so rare that oats may be regarded for practical purposes as free from attack. Of the grasses attacked the most important, from a farming point of view in Western Australia, are Bailey Grass (Hordeum murinum), Silver Grass (Festuca bromoides and F. myuros), and the so-called Spear grasses (Bromus spp.). These annual grasses are very common in the wheat belt.

Bulletin 121 - Mildew, Septoria, Leaf Spots And Similar Diseases Of Cereals, W. M. Carne, J. G. C. Campbell

Bulletins 1 - 2999

Mildew attacks all the cereals as well as many grasses. but as in black stem rust the fungus has developed specialised races, one attacking wheat, another barley, another rye and so on, so that the form attacking wheat will not attack oats, etc

Bulletin 122 - Fruit-Fly: Description And Control, L. J. Newman

Bulletins 1 - 2999

IT is a fundamental principle of Economic Entomology that, in order to successfully combat an insect, the life history of that insect must be worked out. A feature common to all insects is a series of stages involving distinct changes of form which succeed each other in a definite order.

An insect like the fruit-fly affords no exception to this universal rule. Beginning with the fly, we have in regular succession—Egg, Larva, Pupa, and finally the fly again. These stages represent what is known as the life cycle of time insect. Each change—such as larva to pupa, pupa to fly—is …

A Study Of The Environmental Conditions Influencing The Development Of Stem Rust In The Absence Of An Alternate Host. Ii. Infection Studies With Puccinia Graminis Tritici Form Iii And Form Ix, George L. Peltier

Nebraska Agricultural Experiment Station: Historical Research Bulletins

Stakman and Levine have shown that Puccinia graminis tritici (Pers.) Erikss. and Henn. consists of a number of biologic forms, which can be determined by their action on different varieties of Triticum species. To date 37 such biologic forms have been identified by them through the parasitic action on 12 differential hosts chosen from a large number of varieties of Triticum species. To determine whether these biologic forms remain constant in their behavior under various environmental conditions, a detailed study of the host-parasite relation was undertaken with 2 of these forms. At the same time an opportunity was afforded to …

Seed Potato Investigations, H. O. Werner, R. F. Howard

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The objects of the investigations reported in this bulletin were:

• To determine the condition of western Nebraska seed stock by the tuber unit method and by comparative trials in western Nebraska and various other points.
• To determine the effect of culture, place, disease, etc., upon seed value.
• To perfect methods of applying results to seed production in western Nebraska.

Relation Of Environment And Other Factors To Potato Wilt Caused By Fusarium Oxysporum, R. W. Goss

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The present work was undertaken to determine the influence of some environmental factors on the infection and progress of the disease potato wilt. The work has not progressed to the point of determining the exact relation of each of these factors. However, the results thus far obtained are presented here in order to direct attention to the nature and distribution of the disease in relation to the environmental conditions under which certain types of infection take place.

A Study Of The Environmental Conditions Influencing The Development Of Stem Rust In The Absence Of An Alternate Host. I. The Viability Of The Urediniospores Of Puccinia Graminis Tritici Form Iii, George L. Peltier

Nebraska Agricultural Experiment Station: Historical Research Bulletins

No exact data are at hand regarding the influence of temperature and relative humidity on the viability of the urediniospores of stem rust under controlled conditions. 1. The influence of relative humidity on the viability of the urediniospores of Puccinia graminis tritici Form III is very pronounced and closely associated with temperature. 2. At high relative humidities, depending somewhat on the temperature, the percentage of germination is low and the period over which the spores are viable is very short. 3. The same relation exists at the low relative humidities except that it is not so pronounced and is more …

Corn Investigations, T. A. Kiesselbach

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The purpose of the investigations reported in this bulletin has been primarily to determine some of the underlying principles involved in corn improvement. The work comprises a study of some of the physiological characteristics of the crop together with a comparison of various selection, breeding, and cultural practices in their relation to grain yield.

Bulletin No 69 - The Poison Plants Of Western Australia, D. A. Herbert

Bulletins 1 - 2999

Up to the present no publication dealing with the whole of the known i)01S0fl plaits of Western Australia has been written. This Bulletin contains the collected accounts of various authors and correspondents which have been published at different times and contains a large amount of original information gathered both from field experience and from laboratory experiments. The work is not complete. A number of plants from distant districts have not been obtainable or obtainable only in amounts insufficient for exhaustive tests. These plants are comparatively few, however, and in Section 13 of this publication those which are suspected, but against …

Fusarium Blight Of The Soy Bean And The Relation Of Various Factors To Infection, Richard O. Cromwell

Nebraska Agricultural Experiment Station: Historical Research Bulletins

An investigation was outlined (1) to determine the parasitism of Fusarium on soy bean, (2) to establish its relationship to Fusaria of the section Elegans in so far as a comparison of the cultural characters permitted, and (3) by means of cross- inoculations and field studies to determine the relationship of this disease of soy beans to the wilt disease of cowpeas (Vigna sinensis Hassk.) caused by Fusarium tracheiphilum Smith. The results of these investigations up to the close of the summer of 1916 have been reported. The studies were continued at the North Carolina Experiment Station until the …

Studies Of The Etiology And Control Of Blister Canker On Apple Trees, J. Ralph Cooper

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The blister canker caused by Nummularia discreta Tul. is by far the most destructive disease of apple trees found in the United States. Serious damage due to this disease was first reported in Illinois in 1902. Since that time the disease has been reported to cause much damage in all apple-producing sections east of the Rocky Mountains. In Nebraska the disease is so prevalent that it is practically impossible to find an orchard free from it, and in many instances whole orchards have been destroyed thru its attacks. Because of the rapid dissemination and the destructive nature of blister canker, …

Spraying Experiments In Nebraska, J. Ralph Cooper

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The more important questions which were considered during the three years covered by the present report were as follows: 1. How many summer sprays are required and when should they be applied? 2. What is the difference in efficiency between various brands of arsenate of lead? 3. What are the relative values of lime sulphur and Bordeaux as fungicides for spraying apples? 4. Is it possible to lessen or prevent Bordeaux injury and at the same time control fungous diseases? 5. Is it possible to interchange Bordeaux and lime sulphur in a spray schedule in such a manner as to …

A Physiological Study Of Two Strains Of Fusarium In Their Causal Relation To Tuber Rot And Wilt Of Potato, George K. Link

Nebraska Agricultural Experiment Station: Historical Research Bulletins

1. Fusarium tuberivorum Wilcox and Link is the same as Fusarium trichothecioides Woll. 2. Both Fusarium oxysporum and F. trichothecioides can produce both tuber rot and wilt of the potato plant. 3. The wilt is induced by destruction of the root system and by clogging of the xylem elements in the stem, and is, in mild cases, marked by such symptoms as discoloration of leaves, curling and rolling of leaves, and production of aerial tubers. 4. Under field and storage conditions Fusarium oxysporum is more probably responsible for wilt than is F. trichothecioides, and the latter more responsible for …

A Dry Rot Of The Irish Potato Tuber, E. Mead Wilcox, George K.K. Link, Venus W. Pool

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The first specimens of the dry rot herein described were received by the department of Agricultural Botany during the winter of 1907-1908 from western Nebraska. A preliminary survey of the situation showed clearly the importance of this new rot, and an exhaustive investigation of the disease was outlined and has been continued to the present time. The present publication gives the results secured to date in our investigation of this disease.

A Consideration Of The Physiology And Life History Of A Parasitic Botrytis On Pepper And Lettuce, George L. Peltier

Department of Plant Pathology: Faculty Publications

During the autumn of 1911, while gathering the peppers (Capsicum) in the vegetable plat of the Missouri Botanical Garden, the writer observed a fungus which was appearing as a parasite on the fruits. The peduncles were covered with a dark brown mass of conidia and mycelium, which so weakened the tissues that the fruit soon fell to the ground. On opening the peppers a number of large, flat, crust-like sclerotia, 1 cm. long and .5 cm. wide, were found to fill the interior. In most cases the seeds were also covered with the crust-like masses. The conidial stage …

A Study Of The Forage Plants Of South Dakota With Their Fungous And Insect Enemies, David Griffiths

Electronic Theses and Dissertations

The main object of this study being a better acquaintance with fungous parasites, the work on the host plants has been considerably abridged in order that the discussion might be shortened. It was the plan at first to include in this paper a carefully written description of each of the principal forage plants of the state. The futility of such a plan, however, soon became apparent, and it was accordingly decided to omit the description and include simply Distribution,

Habitat, Value as Forage, and the Fungous Parasites of each host. There are, therefore, several of our best forage plants omitted …