Yellow nutsedge (Cyperus esculentus L.) is one of the most serious weeds in New York State. This weed has an extensive distribution in the state where it is a strong competitor with row crops especially corn, beans, and potatoes. Nutsedge is also an important weed problem in many other leading agricultural areas of the United States. The problem in all of these areas has increased recently, possibly due to a reduction of competition from other weeds which are being satisfactorily controlled by selective herbicides.

Simazine, 2-chloro-4, 6-bis (ethylamino)-s-triazine, can give excellent control of annual weeds in corn for most of the growing season. However, a number of workers have reported injury to susceptible crops the year following applications of four or five pounds of simazine per acre. The persistence of simazine is thus of considerable importance to the user who practices crop rotation. The purpose of this study was to investigate factors involved in the dissipation of simazine from the soil.

According to Bonner, at least three different oxidase systems may be involved in the final step of the transfer of electrons to oxygen. Each of the terminal oxidases has been shown to occur in many plants and in many relative combinations.

Several herbicides have been tested for pre-emergence weed control in soybeans. PCP (sodium pentachlorophenate) has given good pre-emergence weed control in soybeans but relatively high rates of 15 to 20 lb/A were required. Although CIPC (isopropyl N–(3–chlorophenyl)carbamate) and NPA (N–1–naphthylphthalmic acid) have given promising results in some tests they have not been uniformly good; CDAA, on the other hand, has consistently controlled annual grasses but not broadleaf weeds.

The wild oat (Avena fatua L.) is one of the most common annual weed species in the northern portion of the great plains region of North America. It has been estimated that up to 70 bushels per acre of wild oat seeds occur in the soil of seriously infested fields. As an impurity in threshed grain it frequently amounts to 10 per cent or more as dockage. To become a serious problem under the climatic conditions and cropping practices of this region, the seed of an annual weed such as wild oats must undergo a period of dormancy and require exacting conditions for its germination. Therefore, investigations to study the factors affecting dormancy and the optimum conditions under which weed seeds will germinate have received considerable attention.

Clagett, Tolbert, and Burris reported an enzyme of widespread occurrence in the green parts of many plants which catalyzed the oxidation of glycolic acid and 1–lactic acid. Zelitch isolated glycolic acid oxidase from spinach leaves and found it to be a flavoprotein with flavin mononucleotide as the prosthetic group. This work was later confirmed by Frigerio and co-workers.

Absinth wormwood (Artemisia absinthium L.), a perennial, native to Europe, has become abundant during the last decade in several locations in western Canada. Reports received during the Saskatchewan Weed Survey suggest that at least some of the introductions into this area were by immigrants from Europe, who believe it to have medicinal properties. Silver-grey in color and covered with fine hairs, the herbaceous stem grows to a height of 2 to 4 ft, often branching profusely. The leaves are up to 5 in. long and are two to three times divided into lanceolate segments. Numerous, drooping heads, about 3/16 in. in diameter, develop in leafy panicles. Yellow or purple florets are borne on a hairy base. The whole plant has a strong, penetrating odor, common in other species of this genus. In Europe it is used as a stimulant (tea and liquor).

Medusahead, Elymus caput-medusae L., is currently the worst range weed in Idaho. It has gained this distinction because of its rapid migration, its vigorous competitive nature, and its extremely low forage value. In the absence of effective control measures, the medusahead problem is becoming more acute each year. The threat that the weed poses to Idaho's livestock industry is sufficient to merit grave concern.

Medusahead, Elymus caput-medusae L., an exotic winter annual grass, was introduced into northeastern Washington and probably adjacent Idaho over 50 years ago. Official records show its presence in southwestern Idaho 15 years ago, but ranchers in this area assert that it was present 25 to 30 years ago. Prior to 1950 it was known to infest a few thousand acres in southwestern Idaho and its distribution from 1945 to 1950 appeared rather static.

Investigations of the competitive effects of Setaria lutescens (Weigel) F. T. Hubb. (yellow foxtail) on corn have dealt primarily with the factors of crop and weed populations, nitrogen fertilizer applications, duration of the period of competition and the amount and distribution of seasonal rainfall. Differences in the competitive efficiencies of various crops and weeds have been demonstrated under various production conditions, but relatively less is known regarding competitive efficiencies among varieties of given crop species. Working under the dryland conditions of Western Canada, Pavlychenko and Harrington compared the competitive efficiencies of several small grains. They ranked barley as the most efficient competitor of weeds, followed by spring rye, wheat and oats in that order. The importance of fertilizer applications in increasing the competitive efficiency of crops has been investigated widely. Previous studies with corn and soybeans have demonstrated some aspects of the role of soil moisture in determining the nature and extent of weed competition in these crops.

The use of herbicides in inter-tilled crops may reduce the number of cultivations necessary for weed control. Thus, in soybeans, how many cultivations are needed when herbicides are used in bands over the row? Overall?

A portable, multiple-tanked spray apparatus has proved convenient and effective for field tests, particularly in steep and remote areas where more elaborate sprayers cannot operate. No hand pumping is necessary and the quickly interchangeable multiple tanks permit mixing and preloading of spray materials in the laboratory. The resultant saving of time in the field often means the difference between completion of a spraying experiment in 1 day rather than 2 or 3, a factor that increases in importance with the remoteness of the research area.

In a recent herbicide development program for control of wild oats (Avena fatua), methods of breaking the dormancy of wild oat seed were studied, since it is difficult to obtain seed with a high rate of germination. One of the theories advanced to explain seed dormancy is that the seed coat acts as a barrier to oxygen penetration. If the seed coat prevents oxygen penetration, then it should be possible to break dormancy by placing seed under high gaseous pressure to force gas through the seed coat, and then rupture the seed coat with a rapid release of pressure.

The use of pre-emergence herbicides where natural rainfall is low and/or sporadic has not been uniformly successful. In general, the results have been erratic; excellent weed control has been obtained sometimes and a complete lack of weed control at other times. Good weed control is usually obtained when one-half inch or more of rain falls within a few days after application. This result is confirmed in irrigated regions by the fact that overhead irrigation usually gives uniformly good weed control. The standard furrow irrigation usually gives erratic results; however, a furrow irrigation which thoroughly saturates the soil with water to the surface may give good results. Since this type of furrow irrigation is difficult to achieve in practice and the equipment necessary for overhead irrigation is not widely used, the physical incorporation of the herbicides in the top few inches of soil is being widely field tested as a method of application in these areas of low and sporadic rainfall. In general, such incorporation has resulted in a much improved performance under furrow irrigation in the absence of rainfall.

During the past several years, pre-emergence herbicides for crabgrass control in turf have come into prominence. Some herbicides are relatively new; others, such as lead arsenate, calcium arsenate, and chlordane, have been used as herbicides for a number of years. Research workers have included the old as well as the newer herbicides in experiments under controlled conditions to determine their effectiveness as pre-emergence herbicides. However, information on the effect of these herbicides on the germination and growth of turfgrass species is limited. Application of lead arsenate as orchard sprays over the years had a toxic effect on the soil after the orchards had been removed and the areas planted to other crops due to arsenic accumulation. The poor condition of young alfalfa and barley in the affected fields was roughly proportional to the concentration of readily soluble arsenic in the surface soil.

Cyperus esculentus L., commonly called yellow nutsedge, is a perennial sedge. The single culms, 2 to 9 cm tall, have at the base a swelling termed a basal bulb. Short, weak rhizomes terminate in tubers.

Crabgrass, Digitaria sanguinalis (L.) Scop., is one of the most troublesome annual turf weeds over much of the United States. In the sub-tropical climate of Southern California its life cycle appears to be quite different from that in most of the United States. To the author's knowledge, its behavior in such a climate has not been described. Studies of its natural development here were conducted in 1959 and 1960.

In Arkansas isopropyl N–(3–chlorophenyl)carbamate (CIPC) is recommended for controlling barnyardgrass (Echinochloa crusgalli (L.) Beauv.) in rice. Method and depth of seeding, time of application, and water management after treatment are critical when using CIPC to control barnyardgrass in rice. Rice is very susceptible to CIPC when roots of the seedlings contact the herbicide. A herbicide that is more selective and less sensitive to management and environment is needed to replace CIPC.

Selective herbicides that will control certain broadleaved but not grassy species or vice versa have been in use for a number of years, but recently selective herbicides have been developed that are toxic to a greater number of weed species. Such an herbicide is 2–chloro–4,6–bis(ethylamino)–s–triazine (simazine) which selectively controls virtually all grassy and broadleaved annual weeds in corn and in some horticultural and woody species. This approaches the ultimate in selective weed control since a farmer usually wants to grow one plant species and eliminate all others.

In the course of an investigation at Madison, Wisconsin, designed primarily to evaluate an improved pea drill, useful quantitative data were obtained relating to weed growth in three different pea populations, verifying the general observation that heavy rates of seeding help to control weeds.