Weed Science Commons^™

Windmill Grass And Its Management, Department Of Primary Industries And Regional Development, Western Australia

Grains and other field crops factsheets

Windmill grass is a native species and the tenth most common summer weed species in the Western Australian (WA) grainbelt. It hosts pests and diseases and utilises stored soil moisture that would otherwise be available to the following crop.

Capeweed And Its Management, Department Of Primary Industries And Regional Development, Western Australia

Grains and other field crops factsheets

Capeweed (Arctotheca calendula) is a prostrate, stemless, sprawling annual herb that germinates during autumn and winter. In Western Australia (WA), competition from 7 to 90 capeweed plants per square metre in a wheat crop can reduce crop yield by 28 to 44% and net return by 25 to 76%.

Tar Vine And Its Management, Department Of Primary Industries And Regional Development, Western Australia

Biosecurity factsheets

Tar vine (Boerhavia coccinea) is a common summer weed species that depletes soil moisture and nutrients, reducing the yield potential of the subsequent crop. It also acts as a green bridge for crop pests and disease.

Diamondback Moth And Its Management In Canola And Crop Weeds, Department Of Primary Industries And Regional Development, Western Australia

Grains and other field crops factsheets

Diamondback moth larvae are a serious pest of canola, brassicas, and forage crops, and are difficult to control. The pest breeds up on summer weeds and volunteer canola plants. If there are abundant early rains and mild winters, diamondback moth larvae pose a risk to canola crops.

Spray-Topping Pastures, Department Of Primary Industries And Regional Development, Western Australia

Grains and other field crops factsheets

Spray-topping or pasture topping is the application of a sub-lethal rate of herbicide when grasses are coming into head and flowering.

The aim is to reduce the production of viable seed and the seedling population in the following year. The grass is not killed by the herbicide application.

Spray-topping is normally carried out in preparation for the following season's cropping program.

Are You Planting Resistant Weeds With Your Crop Seed?, Department Of Primary Industries And Regional Development, Western Australia

Grains and other field crops factsheets

Key messages

• West Australian (WA) grain growers have significant weed seed contamination in their crop seed.

• WA growers are sowing herbicide resistant weed seed into their cropping paddocks.

• Crop hygiene (harvest, seeding, transporting) is important to minimise spread of weeds.

Harvest is well underway throughout the WA grainbelt, and growers will be harvesting grain and collecting seed for next year’s crop.

However, this crop seed can be contaminated with weed seeds and, if seed cleaning operations are only partially effective, this weed seed may be sown into paddocks with crop seed in the following season.

How Much Green To Keep The Garden Clean? An Analysis Of The Willingness To Pay (Wtp) Of Home Gardeners For Biowrap Technology, Gengchen Cai, Kanij Fatema, Karina A. Schoengold

Cornhusker Economics

A research team from the University of Nebraska-Lincoln, Kansas State University, and South Dakota School of Mines are working on creating an alternative product that would use locally available materials to create a spray-on, biodegradable polymer that can suppress weeds and will biodegrade in a timeframe that is amenable to crop production. We broadly refer to this technology as BioWRAP (Bioplastics with Regenerative Agricultural Properties).

Our results show that the home garden market is potentially a significant one for a BioWRAP product. Continued work in the development of the BioWRAP technology is necessary to determine what the cost of a …

Foraging Strategies Of Ruminant Livestock On Intensively Managed Grasslands: Potential And Constraints, I J. Gordon, C Lascano

IGC Proceedings (1977-2023)

All grazed swards exhibit heterogeneity in the spatial (horizontal and vertical) dispersion of species/biomass. A herbivore foraging at random within such a heterogeneous environment would ingest less nutrients than wou Id one which exploited the heterogeneity on offer through selective grazing. The suite of decision-making processes involved in the selective grazing we observe is termed the animal's foraging strategy. On first observation, intensively managed sown swards appear to offer little opportunity for a herbivore to exhibit a foraging strategy; however, opporlunities do exist and there is empirical evidence that herbivores foraging on sown swards tend to have a diet higher …

Comparative Foraging Strategies Of Grazing Ungulates In African Savanna Grasslands, N Owen-Smith, D H.M Cumming

IGC Proceedings (1977-2023)

We review the evolutionary (species-specific) and ecological (individual behavioural) strategies of African grazing ungulates. The contexts considered are free-ranging wild ungulates, traditional livestock pastoralism and extensive commercial ranching. Particularly successful are (1) buffalo, able to digest grass fibre effectively in mesic grasslands; (2) wildebeest, exploiting semi-arid grasslands through migration; (3) megaherbivores (elephant, hippopotamus and white rhinoceros) utilising a wide range of vegetation components. Species-specific adaptations include body size and metabolic rate, digestive efficiency and passage rate, oral and dental anatomy, water dependence and detoxification capacity. Species overlap in grass species se'lected, with dietary differences apparent in grass height favoured, and …

Comparison Of Animal Gains Using Perennial Pastures Exclusively Or Combined With Chicory-Oats-Clover Temporary Winter Pastures, J A. Josifovich

IGC Proceedings (1977-2023)

The increment of winter forage availability using short-rotation pastures could be an interesting way to increase winter carrying capacity. The producer could make good use of higher spring grass production. Sowing oats, rye or chicory alone is quite common in the Argentine Pampa. to evaluate the efficiency of these short-rotation winter pastures a 3 year trial was carried out at Pergamino Experiment Station. The treatments were: a) perennial pastures, 100% of the surface, b) perennial pastures 75%, and chicory-clover 25%, with 2 replications of 3 ha each. The pastures were, for. class II soils, fescue (Festrlca aru11dinacea Schreb.) cv. El …

Influence Of Climatic Factors On Animal Production In The Humid Pampa Of Argentina, J D. Josifovich, E Frutos

IGC Proceedings (1977-2023)

For any' pasture grazing area it is important lo know the relationship among the climatic parameters, rainfall and temperature, with carrying capacity and minimal gains. The availability of pasture to adjust stocking rates and make provisions for hay or supplementary feed needed for periods of shortage can be estimated from these data. Seven years of monthly rainfall and medium average temperature; and 25 years of forage digestibility and average daily gains were related to cattle i: carrying capacity; Analysis was made using the stepwise regression method. Carrying capacity was evaluated considering animal units (AU) for a 400 kg head gaining …

A New Theory Of Feed Intake Regulation In Ruminants And Its Implications For Forage Quality Research, J.J M.H Ketelaars, B J. Tolkamp

IGC Proceedings (1977-2023)

The low voluntary intake of many roughages is commonly explained by a limited physical capacity of ruminants to process fibrous feeds. Recently, we developed a new theory of feed intake regulation assuming feed consumption to create both benefits for the animal (represented by the intake of net energy for maintenance and gain) and costs (represented by the total oxygen consumption of the feeding animal). For non­reproducing ruminants we have shown that voluntary intake of roughages is close to the optimum feed intake level, i.e., the level at which for the animal the ratio between benefits and costs becomes maximum. According …

Botanical Composition Of Forage Samples Selected By Grazing Sheep On The Mountain Rangeland Of Northern China, Han Jianguo, Liu Fuyuan

IGC Proceedings (1977-2023)

Oesophagus fistulae and microscopic examination were used to determine the botanical composition of forage samples selected by grazing sheep on the mountain rangeland in the Hc-Bci Province of northern China during the growing seasons of 1989 and 1990. Results show a clear preference of sheep for some forage species over others. Sheep selected Cleistogenes squarrosa, Koeleria cristata, Potentilla cihinensis, Lespedeza hedysoroides and Scabiosa comosa in each type of rangeland and from early spring to late autumn. The selection ratio of forbs was more than I , and that of grasses less than 1. Sheep showed strong preference for …

The Independent Effects Of Sward Height And Bulk Density On The Bite Parameters Of Romney Ewes And Red Deer Hinds, R J. Mitchell, J Hodgson, D A. Clark

IGC Proceedings (1977-2023)

The independenl effects of sward height (I, 2, 3, 5 and 8 cm) x bulk density (0.65, 1.30, 2.90 mg DM/cm3) variation on the ingestive behaviour of Romney ewes and Red deer hinds were examined in seedling swards which simulated a leafy grass sward of low shear strength. Depth of penetration, horizontal area of herbage severed per bite, weight of each bite and the rate of intake all increased with increasing height, while the rate of biting decreased (P

Relationships Between Milk Yield, Pasture On Offer And Diet Selection In Tropical Grass Pastures, T M. Davison, W N. Orr, V J. Doogan, K Lowe

IGC Proceedings (1977-2023)

A 7-year study was conducted with Holstein-Friesian cows to determine responses to different levels of nitrogen and phosphorus fertiliser applied to Gatton panic (Panicum maximum cv. Gatton) pastures. This study was used to develop relationships between milk yield, pasture and diet botanical components. Multiple regression analysis revealed there was: a negative relation between stem yield (SI) on offer in summer (S) and milk yield but a positive association with leaf yield (L) on offer in summer and green dry matter .GDM in autumn (A),, MY = 2279.0+0.529 LS-0.246 StS+0.324 GDMA _(R2 = 0.66; P

A New Ambulatory Data-Logging System For A Long Term Determination Of Grazing And Rumination Behavior On Free Ranging Cattle, Kanji Matsui, Tadakatu Okubo

IGC Proceedings (1977-2023)

A new ambulatory apparatus (named "jaw recorder") has been developed. The apparatus has a large data storage capacity (32 768 data points), and enables data to be recorded every minute for a minimum of 22 days in one recording session. A Holstein heifer was fitted with the apparatus and was grazed with 4 other heifers for 13 days on a pasture of 0.36 ha of Italian ryegrass (Lolium nmltiflorum Lam.). Grazing and rumination period could be distinguished by a combination of jaw movements and pauses between jaw movements longer than 3 sec/min. Grazing and rumination time distinctly increased with …

Field Test Of Optimal Foraging With Cattle: The Marginal Value Theorem Predicts Patch Selection And Utilization, Emilio A. Laca, R A. Distel, T C. Griggs, G Deo, M W. Demment

IGC Proceedings (1977-2023)

Grazers selectively forage within heterogeneous vegetation. Prediction of intake rate necessitates theoretical developments to understand site selection. We tested III optimal foraging model to predict patch selection by cattle in the field, Nine "grazing environments" (GB) consisting of 16 0.36 m2 patches each were created by mowing. Treatments were a factorial of 3 distances between patches and 3 sets of patch heights. Patch residence time (T,) was accurately predicted (r2=0.89), and increased linearly whh patch distance (P

A Conceptual Model To Explain Variation In Ingestive Behavior Within A Feeding Patch, Emilio M. Laca, M W. Demment, R A. Distel, T C. Griggs

IGC Proceedings (1977-2023)

A conceptual model is presented that links the mechanics of bite formation to the characteristics of the sward to explain variation in bite weight, bite area, bite depth and biting rate measured in a series of experiments with hand-constructed swards. Bite area is determined by the behaviour used by the animal to collect and grasp the tillers, and the length and stiffness of the sward, Bite depth is affected by height and the degree of vertical heterogeneity in stiffness. Time per bite is controlled by bite weight. These mechanisms of bite formation and time per bite ex.plain many observed effects, …

Selective Behaviour Of Cattle Grazing Ryegrass Swards With Horizontal Heterogeneity In Patch Height And Bulk Density, Montague W. Demment, R A. Distel, T C. Griggs, E A. Laca, G P. Deo

IGC Proceedings (1977-2023)

Patches of different height and/or bulk density were created in ryegrass pasture to study selective responses of steers to horizontal variability in patch structure. The experiment involved 3 heterogeneity treatments with 2 patch types each. Steers encountered and entered both patch types available in each treatment with the same frequency. In contrast, they grazed for a longer time (T,) at; and removed more bites (B) from the patch type that yielded greater intake rates. While T, and B varied for a patch type depending on the alternative patch, bite rate and likely bite size were constant for a given patch …

Computer Recording Of The Variation In Intake Of Supplements Provided To Grazing Cattler, R M. Tait, L J. Fisher

IGC Proceedings (1977-2023)

A computer system has been developed to record the consumption of' supplements provided free choice to grazing cattle. The system is based on electronic animal identification and one or more weatherproof electronic scales located in simple feed stations connected by telephone cable to a computer at a distance of up to 1 km. The software program identifies and records individual animals, • time and duration of visits, and the quantity of supplement consumed. The system has been tested in the field using 40 kg molasses-based feed blocks with up to 20 steers per feed station in paddocks of approximately 4 …

Diet Selection By Lambs In Ryegrass-White Clover Swards Differing In The Horizontal Distribution Of Clover, R H. Armstrong, E Robertson, C S. Lamb, I J. Gordon, D A. Elston

IGC Proceedings (1977-2023)

Weaned 5-month-old lambs grazed 2 series of perennial ryegrass (Lolium perenne L.) plots containing patches of mixed perennial ryegrass and white clover (Trifolium repens L.) varying in either a) the size of patches or b) the distance between patches. Both series embraced the same range of percentages (1-25) of ryegrass-clover patches in each plot. Diet composition was estimated from the pattern of naturAI alkanes in faeces collected between days 6 to 15 after allocation of the lambs to the treatments. The percentage of clover in the diet declined markedly from days 6 to 11 and thereafter increased slightly. Dietary …

Influence Of Ectoparasites On Ingestive And Meristic Behavior Of Grazing Beef Cattle, C T. Dougherty, F W. Knapp, P B. Burrus, N W. Bradley

IGC Proceedings (1977-2023)

Face flies (Musca autumnalis De Geer) and slable flies (Stomoxys calcitrans L.) were raised in the laboralory and released into 12 enclosures, each with I grazing cow (Bos taurus L.). Releases of 0, 400 and 800 face flies gave 3, 53 and 64 lighted flies/cow, respectively, with 30/head al the 400 and 800 levels, and eliciled head (2, 60 and 39/h), ears (8, 1337 and 859/h), tails (24, 191 and 606/h) movements and skin twitches (1 side) (15, 210 and 248/h) but did not induce leg movements or affect number of feeding stations visited (188/h), Face flies …

Dung Bags To Prevent Dung Pat Formation In Pasture By Grazing Cattle, Sakurai Mosaku

IGC Proceedings (1977-2023)

In order to prevent dung pat formation on intensively grazed pasture in the humid temperate zone, a modified dung bag was made. Results from a preliminary study showed that smaller dung lumps dropped in the pasture resulted in the period of rejection being shorter and the rejected area being smaller or non existent. The dung bag was remodeled and fitted to the milking cows. After excretion the dung is held in the dung bag. From a hole in the bottom of the bag smaller dung lumps fall to the pasture. Therefore larger dung pat formation is prevented and the area …

Vegetation Utilization And Dynamics In Hill Pastures Dominated By Calluna Or Agrostis-Festuca-Nardus And Grazed By Sheep Or Cattle, R Celaya, M Olivan, K Osoro

IGC Proceedings (1977-2023)

The dynamics of Agrostis-Festuca-Nardus. grasslands and Calluma heathlands with broom on plots with different ratio of area covered by each community type and grazed either by cattle or sheep were monitored during summers of 1990 and 1991. Significant differences were observed. Cattle grazed Nard11s more intensively than sheep and Cai tuna cover . was more, slrongly affected by cattle than sheep grazing. Brooms were grazed intensively by sheep but were rejected by cattle.

Diet Selection, Diet Quality, Dry Matter Intake And Growth Rate Of Cattle Grazing Tropical Grass-Legume, D B. Coates, A J. Ash, R W. Mclean

IGC Proceedings (1977-2023)

Dietary attributes and growth of cattle grazing tropical grass-legume pastures were ex.amined in 2 experiments in northern Queensland. Pastures oversown with legume gave substantial improvements in dietary ,nitrogen, digestibility and dry mauer intake compared with native 1rass pasture. On phosphorus (P)-deficient soils, applying P fertiliser or supplementing with P, improved P jntake, feed intake and growth rate of .cattle. Once nitrogen and P deficiencies were overcome, it was com:luded that diet digestibility was the main factor limiting the growth. of cattle and that the severity of this limitation was determined primarily by seasonal conditions.

Variation In Intake Rate And Mastication By Grazing Steers In The Spring, G P. Cosgrove, J C. Burns, D S. Fisher, K R. Pond, J P. Mueller

IGC Proceedings (1977-2023)

Changes in intake ,ate (IR), bite mass (BM), and biting rate (BR) and ingestive mastication of tall fescue (Festuca arundinacea Schrcb; TF), orchardgrass (Dactylis glomerata L; OG) and ryegrass (Lolium perenne L: RG) were studied over 3 grazings between early spring and early summer of 2 consecutive years. Defoliation by steers started at 100 mm canopy height (Tl) and terminated at 50 mm (T2). At Tl, and again at T2, ocsophageal-fistulated steers were used to estimate IR, BM and BR and to provide extrusa samples for determination of 1nasticatc particle size after dry sieving. At Tl there …

Varietal Differences In The Heifer Preference Of Orchardgrass, K Mizuno, S Shioya, F Fujimoto, M Kanbe

IGC Proceedings (1977-2023)

Heifer preferences of 14 varieties of orchardgrass (Dactylis glomerata L.) were studied using a tough cafeteria method throughout the growing season in 1991. Highly significant differences in heifer preferences between varieties were recognised through the 1st harvest in April to the 6th harvest in November. Several agronomic characters were negatively correlated with heifer preferences in each harvest: stage of maturity in the spring growth, occurrence of rhynchosporium scald (Rhynchosporium ortliosporum Caldwell) in the summer regrowth in July and of stem rust (Puccinia graminis Pers, f. sp. dactylitis Guyot and Massenot) in the autumn regrowth. However, leaf flexibility was …

Comparison Of Bite Weight And Bite Dimensions Of Sheep And Goats Grazing A Range Of Grasses And Clovers, Y Gong, J Hodgson, M G. Lambert, A.C P. Chu, I L. Gordon

IGC Proceedings (1977-2023)

Response patterns in bite weight and bite dimensions of sheep and goats were evaluated using 3 grasses and 3 clovers sampled at 2 stages of maturity offered as prepared turves to animals confined in metabolism crates. Average bite weight across 12 sward types (6 forages x 2- stages) was similar for sheep and goats, but goats had greater bile weight per unit LW0•75 tlian sheep, Despite being shorter, the much denser clover swards resulted in larger bite weight than did grass swards. The taller reproductive swards enabled animals to harvest greater bite weights than did vegetative swards. Sheep obtained heavier …

Influence Of Sward Characteristics On The Diet Selected By Grazing Sheep In Perennial Ryegrass Swards Maintained At Two Sward Heights, H Clark

IGC Proceedings (1977-2023)

Perennial ryegrass (Lolium perenne L.) swards were continuously but variably stocked to maintain a sward surface height (SSH) of either 4 cm or 3cm for 2 grazing seasons (1983, 1984). The lower sward height resulted in less length of leaf per tiller but this was balanced by a higher tiller population such that there were only small differences between the swards in green leaf mass per ha. In 1984 the green tissue ai1d the green leaf mass increased on both swards despite there being no change in the average sward height. This was due to an increased length of material …

Relationship Between Sward Structure And Dietary Quality And Intake, In Cattle Grazing Humid Sour Grassveld In South Africap, P J. O'Reagain, M Haller, P.J K. Zacharias

IGC Proceedings (1977-2023)

The relationship between sward structure, and dietary quality and intake was investigated for cattle grazing humid sour grassveld in south Africa. A 2-ha site was divided into 6 equal-sized blocks with; each block being managed to achieve a different sward structure using rotation·a1 grazing of cattle at 3, 5, 8, 11, 16 or 20 week intervals. Before to grazing, sward structure was quantified in terms. of tuft height, leaf table height, stemminess and greenness of the 3 most abundant species as well as sward leaf density. Oesophageal i fistulates were used to estimate dietary quality, bite rate, bite size, and …