Weed Control by Means of Chemicals

Weed control by means of chemicals has become an important factor in our struggle to eradicate weeds. There are few weed problems which chemicals cannot at least aid. However, in many cases, their use is limited by their cost. It has generally been held that chemicals are too expensive for large infestations of weeds. In northwest Iowa where there are thousands of acres of European bindweed (Convolvulus arvensis L.) chemicals of the present day cannot be recommended on account of the cost. To control this noxious weed it has been necessary to resort to cultivation and competitive cropping, processes which take several years, and have for their objective a reduction in the amount of food reserves in the subterranean parts, to the point where there is not sufficient food material to regenerate new shoots

Leafy Spurge, Euphorbia Esula L.

Leafy spurge (Euphorbia Esula L.) has become a serious menace to agriculture in northwest Iowa and in the adjoining states, Minnesota, North and South Dakota. It was collected at Mount Pleasant (Henry County) in 1899 and at Ames (Story County) in 1907. This weed seems to develop most vigorously in northwestern Iowa, where large patches occur on many farms. In order to determine the most effective means of exterminating this weed pest, it was necessary to learn more about its life history, growth, habits and structure in areas where it was well established. An attempt has been made in this publication to place leafy spurge in its correct place taxonomically and to discuss the flowering, fruiting habits, pollination, seed studies, seed dispersal, root system, leaf, stem and root structures

Soil Moisture Relationship of the European Bindweed (Convolvulus Arvensis L.)

The European bindweed (Convohrulus arucnsis L.) has an extensive root system. A large number of feeding roots are located in the upper two feet but the main tap root often extends to a depth of twenty feet. Soil samples taken at one and two foot depths in 1933, 1934 and 1935, at Hawarden, Iowa, from corn ground, heavily infested with bindweed, and free from bindweed, showed very little difference in soil moisture content. As the soil moisture content was often below the wilting coefficient, it was found that the bindweed developed readily while the corn grew very little. European bindweed is able to complete successfully with corn because of its deeply penetrating root system

Control and eradication of European Bindweed

The European bindweed (Convolvulus arvensis L.), known also as Creeping Jennie and field bindweed, probably is present in every county in Iowa, although it is more prevalent in the northwestern part of the state. It is not uncommon to find tracts of 100 acres or more. Where a small grain field is heavily infested, the grain becomes lodged so that it is extremely difficult to cut with a grain binder, and the bundles do not dry readily. At times throughout the years 1930-1941, bindweed caused a complete failure of corn (fig. 1), grain and garden crops on certain tracts. In the states where European bindweed is most troublesome today, the weed was not serious up to the beginning of the twentieth century. This bulletin reports information obtained during the past 10 years from the experimental work on eradication of European bindweed at Hawarden and Cherokee, Iowa. The recommendations submitted are particularly applicable to Iowa

The Use of Tetrachlorethane in the Eradication of the European Bindweed (Abstract)

Tetrachlorethane, made by the addition of chlorine to acetylene, has proved to be effective in killing the European bindweed. By making holes 18 inches deep and having the holes 18 inches apart and placing two ounces of tetrachlorethane in each hole, a complete eradication of the European bindweed may be made with one application

The effect of city smoke on vegetation

A study of the smoke problem in Des Moines establishes clearly that the smoke and gases emitted by its many power and heating plant chimneys have a harmful effect upon trees, shrubs and other vegetation. To a large extent, plants serve as good indicators of smoke contamination in a community. In the immediate neighborhood of the smoke emitting establishments in Des Moines, only a few of the most resistant plants grow, all others being eliminated, A little farther away, where the smoke and gases are not so dense, some additional plants are found and so as the distance increases the number of plants increases until an area is reached where the air is not much contaminated and vegetation is normal. Around each large manufacturing establishment the vegetation may be mapped in belts of varying width, in each of which certain forms of plant life may be found, depending on susceptibility of smoke injury. In much the same way the entire area of Des Moines may be mapped in belts according to the influence of smoke injury on vegetation

The Effect of Smoke on Plants

Almost every industrial town or city in the United States has at least one thing in common, and that is smoke. It is only of comparative recent date that smoke has been given serious consideration, outside of the office of smoke inspector and members of the anti-smoke league. The question of smoke is not a new one, for publications as to injury and legislation, date back to 1845. But since that time, we have had the great movement of people from the country to the city, in addition to the great immigration tide and the result is that large industrial centers have been built up. Smoke then has been considered as a \u27\u27necessary evil\u27\u27 and has been looked upon as showing signs of prosperity to such centers

Controlling Canada Thistle With 2,4-D

Canada thistle is resistant to 2,4-D. Many farmers using 2,4-D have killed the tops only to see new shoots come up from the roots

Experiments on the control of European Bindweed (Convolvulus arvensis L.)

European bindweed (Convolvulus arvensis L.) is found in every county in Iowa. It is more prevalent in the western and northwestern parts of the state where 100-acre tracts are common. Many farms have become heavily infested during the last 10 years. European bindweed reduces crop yields, increases the cost of production, threatens land which is free of weeds and finally reduces all land values in its vicinity. It is a serious pest not only in Iowa but also in South Dakota, Minnesota, Nebraska, Kansas, Colorado, Idaho, Washington, Utah and California. It occurs in northeastern North America and sparingly in southeastern United States. Although considerable work has been done on the control of European bindweed, the methods are still indefinite and conflicting. The purpose of this publication is to show the effectiveness of a number of chemicals and different cultural practices in its control and extermination

The Late Blight of Barley (Helminthosporium teres Sacc.)

To the barley grower, no other disease of the barley is probably of such economic importance as the late blight (Helminthosporium teres). When active work was begun in the summer of 1909, certain barley plots of the college showed that more than 90 per cent of the plants in those plots were infected. The disease presents itself in the form of brownish, orange colored spots, which at first are oval or circular, but later become elongated. As a result of infection, the greater surface of the leaves takes on a yellowish color. In contrast to this effect is the brick red color of the spotted areas. A marked feature, as a result of an examination of a diseased plant, is that a single individual shows all stages of attack. Ordinarily the fungus is noticed in this locality, during the early part of July. Usually at that time, the basal leaves will have become completely dried, while those above will show a progressive decrease to the point where no spots are present. This disease is closely related to the Yellow Leaf. The last named form is not so destructive for the reason that Yellow Leaf singles out individual plants, while the Late Blight is broadcast in its attack