Control of Medusahead (Taeniatherum caput-medusae) and other Annual Grasses with Imazapic

2007 ◽  
Vol 21 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Guy B. Kyser ◽  
Joseph M. Ditomaso ◽  
Morgan P. Doran ◽  
Steve B. Orloff ◽  
Robert G. Wilson ◽  
...  

Invasive annual grasses, such as medusahead, can reduce forage production capacity and interfere with revegetation projects in California rangelands. Because of the taxonomic similarity to other more desirable grasses, achieving selective control of invasive annual grasses can be difficult. In selectivity trials conducted in Yolo and Siskiyou counties, CA, the herbicide imazapic gave control of many nonnative annual grasses yet provided some level of selectivity to specific perennial grasses used in revegetation projects throughout the western United States. The selectivity difference between newly seeded perennial and annual grasses was greater with PRE applications than with POST treatments. Both perennial and annual grasses within the tribe Hordeae were more tolerant to imazapic than other grass species. In addition, field experiments were conducted at three sites in northern California (Yuba, Yolo, and Lassen counties) and one in southern Oregon (Lake County) to test the response of imazapic to varying management conditions. Imazapic was applied PRE in fall (and also spring in Lake County) at rates from 35 to 210 g/ha on undisturbed rangeland, in comparison with rangeland cleared of standing plant material and thatch by either tillage, mowing and raking, or burning. Imazapic generally showed enhanced weed control when applied following disturbance. Rates as low as 70 g/ha, if combined with thatch removal, provided significant suppression of medusahead. In addition, disturbance alone generally reduced medusahead cover in the following year. Although imazapic showed potential for control of medusahead and other annual grasses, its selectivity window was relatively narrow.

1990 ◽  
Vol 4 (2) ◽  
pp. 245-249 ◽  
Author(s):  
Brenda S. Smith ◽  
Don S. Murray ◽  
J. D. Green ◽  
Wan M. Wanyahaya ◽  
David L. Weeks

Barnyardgrass, large crabgrass, and Texas panicum were evaluated in field experiments over 3 yr to measure their duration of interference and density on grain sorghum yield. When grain yield data were converted to a percentage of the weed-free control, linear regression predicted a 3.6% yield loss for each week of weed interference regardless of year or grass species. Grain sorghum grown in a narrow (61-cm) row spacing was affected little by full-season interference; however, in wide (91-cm) rows, interference increased as grass density increased. Data from the wide-row spacing were described by linear regression following conversion of grain yield to percentages and weed density to log10. A separate nonlinear model also was derived which could predict the effect of weed density on grain sorghum yield.


Author(s):  
А.А. Анисимов ◽  
П.И. Комахин ◽  
В.Н. Золотарев

Важнейшей проблемой продовольственной безопасности страны является уровень обеспеченности населения молочными продуктами. В связи с этим большое значение имеет опыт работы передовых хозяйств такого профиля в определённых почвенно-климатических и природно-экологических условиях. ФГБУ «Опытная станция «Пойма» является одним из наиболее эффективных хозяйств в Московской области по производству молока. Общая площадь сельскохозяйственных угодий составляет 6135 га, из них 2000 га пашни. В структуре посевных площадей 95% и более занимают кормовые культуры, в том числе 12–14% — однолетние травы, 68–70% — многолетние травы и природные кормовые угодья, 15–16% — кукуруза на силос. Основное производство кормов сосредоточено на высокоплодородных пойменных землях, на долю которых приходится 84% кормовых угодий. В статье изложены результаты системного применения достижений науки и передового опыта по стабильному производству высококачественных объёмистых кормов. Проведён анализ состояния кормопроизводства и животноводства хозяйства с 1982 по 2020 год, освещены научные подходы к увеличению производства кормов и животноводческой продукции. Системное освоение передовых научных разработок по созданию высокопродуктивных кормовых посевов и стабильному производству высококачественных объёмистых кормов, их рациональному хранению и использованию, техническая модернизация позволили увеличить среднегодовой надой на корову с 4079 до 9708 кг, или более чем в 2,3 раза, при одновременном снижении расхода кормов на 1 кг молока с 1,37 до 0,90 корм. ед. при повышении рентабельности с 16 до 28%. Food safety of the country is highly affected by the availability of milk products. Therefore, the experience of leading farms is of great importance under certain environmental conditions. The Research Station “Poyma” is one of the leading milk producers in the Moscow region. Its fields occupy around 6135 ha. The proportion of forage crops amounts to 95% including 12–14% of annual grasses, 68–70% of perennial grasses and natural forage lands as well as 15–16% of maize for silage production. 84% of the total cultivation area are high-fertile floodlands. This article focuses on the application of the latest scientific findings and advanced experience for stable production of high-quality bulk fodder. The efficiency of forage production and Animal Husbandry was analyzed in the period from 1982 to 2020. The methods and practices were reviewed to optimize forage and animal product resources. Average annual milk yield was improved from 4079 to 9708 kg per cow, or by more than 2.3 times due to the introduction of the latest findings into the production process including the cultivation of high-productive forage crops, stabilization of bulk fodder supplies, feed effective storage and use. Forage consumption dropped from 1.37 to 0.90 feed units for the production of 1 kg of milk, payback increased from 16 to 28%.


2006 ◽  
Vol 54 (7) ◽  
pp. 655 ◽  
Author(s):  
Tanja I. Lenz ◽  
José M. Facelli

The species composition of temperate grasslands in the mid-north of South Australia has been radically altered from a system dominated by native perennial grasses to a system dominated by Mediterranean annual grasses. This study investigated the importance of chemical and physical soil characteristics, topographical features and climatic variables on the abundance of native and exotic grass species in nine ungrazed grasslands. Overall, climatic and other abiotic factors were highly variable. In addition, past management practices and original species composition are generally unknown, leading to further unexplained variation in the data. On a large spatial scale (among sites), the abundance of exotic annual grasses was positively correlated with mean annual rainfall, and on any scale, with finer soil textures and higher soil organic carbon levels. The most abundant annual grass, Avena barbata (Pott ex Link), was generally associated with soil factors denoting higher soil fertility. The abundance of native perennial grass species was not correlated with any environmental variables at any scale. The various native perennial grass species did not show clear associations with soil factors, although they tended to be associated with factors denoting lower soil fertility. However, at small spatial scales (within some sites) and among sites, the abundances of exotic annual and native perennial grasses were strongly negatively correlated. The results suggest that at the present time, rainfall and soil properties are important variables determining the abundance of annual grasses. The driving variables for the abundance of perennial grasses are less clear. They may be controlled by other factors or extreme rainfall events, which were not surveyed. In addition, they are likely to be controlled by competitive interactions with the annual grasses.


Weed Science ◽  
1984 ◽  
Vol 32 (S1) ◽  
pp. 13-17 ◽  
Author(s):  
Raymond A. Evans ◽  
James A. Young

The sagebrush (Artemisia)-grass ecosystem is an extensive and important rangeland type in the western United States. Estimates of total area of this ecosystem vary from 38 million ha (21, 22) to 109 million ha (3). Of the sagebrush-grass rangelands, 88% are degraded to the point that they are producing 50% or less of their forage potential (22). Low forage production on these rangelands has been caused by overgrazing and other past land abuses (24) resulting in severe depletion of native perennial grasses, dominance of brush, and, on millions of hectares, downy brome (Bromus tectorumL. # BROTE) dominance of the understory.


1963 ◽  
Vol 41 (8) ◽  
pp. 1171-1185 ◽  
Author(s):  
J. T. Slykhuis

Wheat striate mosaic virus from wheat in southeastern Saskatchewan was acquired and transmitted by both nymphs and adults of the leafhopper Endria inimica (Say) collected in Ontario. The preinfective period of leafhoppers varied from 4–6 to 22–24 days after they first fed on diseased plants. Records of serial transmission by individual insects varied greatly. Some insects infected most test plants on which they were given 2-day feeds during 20 to 30 days after the preinfective period, but subsequently they transmitted irregularly. Some transmitted virus for only a few days. Others transmitted intermittently for several weeks. None of the insects infected any plants on which they fed later than 72 days after feeding on diseased plants even though some lived another 10 to 20 days. Two of 25 insects became infective after feeds as short as 30 seconds on diseased plants, but the percentages of infective insects increased to more than 90% as acquisition access times were increased to 2 or more days. All insects from some inbred lines became infective after 3 days on diseased plants, but 45% of the descendants of one non-transmitting female failed to become infective. The inoculation threshold period on Ramsey wheat test plants was 15 minutes, but the percentage of test plants infected increased from 15% to 88.8% as the test access times were increased to 4 days. The incubation period of the virus in Ramsey wheat seedlings varied from 6 to more than 28 days.In tests of host reactions, all durum wheat varieties were highly susceptible to the virus. Several of the hard red spring and winter wheat varieties were highly susceptible and a few others were highly resistant or immune, but most were mildly to moderately susceptible. Most varieties of oats and barley and 10 species of wild annual grasses were moderately susceptible. Mild to moderate symptoms also developed on some of the plants in one or more varieties of Zea mays L., Lolium multiflorum Lam., L. perenne L., and Bromus inermis Leyss. Four varieties of rye tested did not develop symptoms, nor did any plants in 13 species of perennial grasses, including Chloris gayana Kunth, which is susceptible to the Australian wheat striate mosaic virus. E. inimica multiplied on wheat and 14 other annual and 21 perennial grass species, many of which are common on the prairies. There was considerable variation in the reactions to the virus of different plants in the variety Ramsey, but there were no inherent variations detected between the virus isolates used for the experiments. The wheat varieties Cappelle-Desprez and Rescue which are highly susceptible to the European type of wheat striate mosaic virus did not become infected with the Canadian isolates tested.Attempts to transmit the European type of wheat striate mosaic virus with E. inimica failed.


1973 ◽  
Vol 24 (2) ◽  
pp. 271 ◽  
Author(s):  
BA Hamilton ◽  
KJ Hutchinson ◽  
PC Annis ◽  
JB Donnelly

Oesophageal extrusa samples were collected from sheep grazing monospecific swards of four temperate perennial grasses. The in vitro digestibility and the proportion of green plant material in the extrusa samples were related exponentially to the yield of herbage on offer. The digestibility of ingesta was highly correlated with the yield of green herbage. When the yield of green herbage exceeded c. 550 kg/ha the sheep selected a diet more digestible than the mean of the green plant material on offer, and when there were low amounts of green herbage available the ingesta was less digestible than the green plant material on offer because of the low proportion of green plant material eaten. A relationship between the proportion of green plant material in extrusa samples and the green herbage yield was determined for each species, and no significant difference in regressions between species was found. It is suggested that the pooled relationship obtained in this study may be used to predict the proportion of green plant material in the ingesta of sheep over a range of grass species and yields.


2001 ◽  
Vol 28 (4) ◽  
pp. 445 ◽  
Author(s):  
P. L. Dostine ◽  
G. C. Johnson ◽  
D. C. Franklin ◽  
Y. Zhang ◽  
C. Hempel

The diet, attributes of feeding sites and patterns of seasonal movements of a population of the Gouldian finch, Erythrura gouldiae, were studied in the Yinberrie Hills area north of Katherine in the Northern Territory. In the dry season (April–November) Gouldian finches foraged mostly on burnt ground and fed on exposed seed of annual grasses, especially seed of spear-grass, Sorghum spp. In the wet season (December–March) Gouldian finches fed on seed of a sequence of perennial grass species, including Themeda triandra, Alloteropsis semialata, Chrysopogon fallax and Heteropogon triticeus. Gouldian finches undertake regular seasonal shifts in habitat, from breeding areas in hill woodland in the dry season to adjacent lowlands throughout much of the wet season, in response to seasonal changes in food availability. There is an annual pulse in abundance of fallen seed in the early dry season that is depleted to near zero levels by germination of annual grasses early in the wet season. Thereafter, finches depend on seed from other sources, principally ripe and ripening seed of perennial grasses. Observations over three successive wet seasons suggest that Gouldian finches track seed resources provided by seeding perennial grasses over an extensive area of lowland grassy woodland adjacent to the breeding area, favouring small patches of grassy woodland for brief periods until seed fall. There were subtle differences between years in the types of resources used. Management of Gouldian finch populations will entail protection and management of the full range of grassland habitats used throughout the annual cycle, and will require predictive knowledge of the causes of patterning of seed resources and probably an ability to exert control over the timing and extent of fires in fire-prone seasonal savanna landscapes.


2011 ◽  
Vol 27 (3) ◽  
pp. 599-614 ◽  
Author(s):  
D. Sokolovic ◽  
J. Radovic ◽  
Z. Tomic

Temperate forage grasses are the main components of grasslands occupying 40.5 % of the world?s terrestrial area and 30-40% of European agricultural area. They cover the land, providing a habitat and a source of food for domestic livestock, thus ensuring a supply of livestock products, with contributes to rural agricultural and economic development. Grasses are a natural food for ruminants. Rich in fibre, they provide the bulk necessary for good rumen function. Eaten at a sufficiently young stage, they are highly digestible and contain lot of energy. At this stage they also have high mineral and protein contents that cover a large part of animals? requirements. Grasslands usually produce the majority of the forage ingested by ruminant animals during grazing season. During winter housing grass hay and silage are often major parts of the staple diets. There are many improved grass genotypes in Serbia that share main characteristics: high yield and quality of dry matter within a target group of environments and in particular agricultural context. Beyond this common breeding goal there are vast of forage breeding programs as varied as the species upon which they are based and the breeders who develop and implement them. The intensification of forage production and utilization, especially during the second half of the twentieth century, led to a drastic reduction in the number of grass species in sown mixtures, as well as in permanent grasslands. Only a small number of species mainly the ryegrasses, timothy, cocksfoot and fescues are highly suited to intensive management. Moreover, in Europe from 1980 onwards, many forage systems were deintensified and wild or hardly selected species became more important in grasslands. Therefore, it is evident that importance of perennial grasses as animal feed will be increased in the future.


2011 ◽  
Vol 4 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Gustavo M. Sbatella ◽  
Robert G. Wilson ◽  
Stephen F. Enloe ◽  
Charlie Hicks

AbstractVigorous stands of perennial grasses can effectively provide long-term control of many invasive plants on rangelands. However, in degraded conditions, successful reestablishment of perennial grasses can be compromised by invasive annual grasses, such as downy brome. Propoxycarbazone-sodium is a selective herbicide currently labeled for downy brome control in small grains, but its potential use on rangelands is unknown. Studies were conducted from 2004 through 2008 at three rangeland sites in Colorado and Nebraska to evaluate downy brome control and perennial grass injury with propoxycarbazone-sodium and imazapic. Propoxycarbazone-sodium provided satisfactory downy brome control with grass injury equal to or less than imazapic when rainfall followed the fall application. A second set of studies was conducted from 2007 to 2008 at Lingle, WY, and Scottsbluff, NE, to determine the plant-back interval and postemergence application response of seven perennial grass species to propoxycarbazone-sodium and imazapic. Grass tolerance to both herbicides was good when applied 90 and 120 d before planting (DBP). However, grass injury increased as plant-back interval decreased. The greatest impact on plant biomass was observed from herbicide applied at planting or after planting. Crested and intermediate wheatgrass (Agropyron cristatumandThinopyrum intermedium) biomass production was not affected when herbicides were applied 90 or 120 DBP. Western wheatgrass (Pascopyrum smithii) and Russian wildrye (Psathyrostachys juncea) showed tolerance to imazapic applied before planting. Smooth brome (Bromus inermis), sheep fescue (Festuca ovina), and orchardgrass (Dactylis glomerata) showed the least amount of tolerance to propoxycarbazone-sodium and imazapic.


2011 ◽  
Vol 62 (7) ◽  
pp. 591 ◽  
Author(s):  
R. Thapa ◽  
D. R. Kemp ◽  
D. L. Michalk ◽  
W. B. Badgery ◽  
A. T. Simmons

Two field experiments, one each on Austrodanthonia spp. and Bothriochloa macra, investigated the effects of biomass manipulation, seed level modification, site preparation and pasture composition on the recruitment of native perennial grass seedlings. The experiments coincided with drier than average years and although successful emergence of seedlings occurred, survival was extremely low. In the Austrodanthonia experiment, control treatments resulted in the emergence of only 1 seedling/m2, whereas there were 130/m2 in the best treatment which had biomass cut with plant material removed, seed added, and the soil surface scarified. Insecticide treatments increased emergence as seed-harvesting ants are common in these systems, but the benefits were small. Similarly, B. macra had no emergence in the control treatment compared with 73 seedlings/m2 in the best treatment, which was pasture cropped, and had seed added and herbicide applied. Availability of microsites may be a major constraint to B. macra emergence, as soil disturbance through pasture cropping substantially increased seedling numbers (279/m2). The effects of herbicide on emergence were small with the largest being related to bare ground and litter biomass. Austrodanthonia seedling numbers at emergence were related to bare ground, litter and green biomass. Survival of young Austrodanthonia plants 24 weeks after emergence was negatively related to plant cover, but only in treatments where plant material was cut and removed. The success of survival was determined at 52 weeks after emergence and the number of young plants that survived in both experiments seemed to have been influenced by the presence of competitive biomass of existing plants.


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