Variation in Weed Seed Fate Fed to Different Holstein Cattle Groups.

Weed seeds may maintain their viability when passing through the digestive tract of cattle and can be therefore dispersed by animal movement or the application of manure. Whether different cattle types of the same species can cause differential weed seed fate is largely unknown to us particularly under non-grazed systems similar to Holstein-Friesian dairy farming. We investigated the effect on the seed survival of four weed species in the digestive tracts of four groups of Holstein cattle: lactating cows, feedlot male calves, dry cows and growing heifers. The weed species used were Cuscuta campestris, Polygonum aviculare, Rumex crispus and Sorghum halepense. Cattle excretion was sampled for recovery and viability of seeds at four 24 hourly intervals after seed intake. The highest seed recovery occurred two days after seed intake in all cattle groups. Averaged over weed species, dry and lactating cows had the lowest and highest seed recovery of 36.4% and 74.4% respectively. No significant differences were observed in seed recovery of the four weed species when their seeds were fed to dry cows. Based on a power model fitted to seed viability data, the estimated time to 50% viability loss after seed intake, over all cattle groups ranged from 65 h (R. crispus) to 76 h (P. aviculare). Recovered seeds from the dung of feedlot male calves showed the highest mortality among cattle groups. Significant correlation was found between seed viability and ruminal pH (r = 0.86; P<0.05). This study shows that management programs aiming to minimize weed infestation caused by livestock should account for the variation amongst cattle groups in seed persistence. Our findings can be used as a guideline for evaluating the potential risk of the spread of weeds via the application of cattle manure

Evaluation of Rigid Ryegrass (Lolium rigidum) accessions for clodinafop-propargyl Resistance using bioassay in Petri dish and pot

Three rigid ryegrass accessions with possible resistance to clodinafop-propargyl, anacetyl-CoA carboxylase (ACCase) inhibitor (group 1) herbicide were identified in Farsprovince fields. Greenhouse studies and seed bioassay experiments were conducted toconfirm clodinafop-propargyl resistance in Lolium rigidum L. In Petri dish seed bioassay testwere determined the coleoptiles length of accessions (as % of untreated control), ID50(dosage required to inhibit coleoptile length by 50%), the degree of resistance in S and Raccessions. In greenhouse experiments to determine the degree of resistance, accessions wereexposed to clodinafop-propargyl at 4-leaf stage. Four weeks after spraying was calculated thedry weight of accessions (%), plant survival of each accession (% of untreated control) andevaluation was performed according to EWRC. Then, the responses of accessions exposed to0.25 to 32 times the recommended dosage of clodinafop-propargyl was measured and thedegree of resistance in S and R accessions was identified. Results of bioassay andgreenhouse studies revealed that in both experiments and for parameters measured FR1accession showed more resistance than the other accessions, followed by FR7 and Saccessions, respectively. So these two methods tested can be used to help assess the degree ofresistance and reached the same result with two methods

Investigations of Field Performance and Physiological Effects of Metsulfuron and Metsulfuron Combinations on Field Bindweed (Convolvulus arvensis L.)

Field bindweed (Convolvulus arvensis L.) is a noxious perennial weed of many fallow and cropland fields all over the world. Present control methods are not satisfactory for field bindweed. Metsulfuron, 2[[[[(4-methoxy-6-methyl-1,3,5-triazine-2-yl) amino] carbonyl] amino] sulfonyl] benzoic acid, is a new herbicide that has been shown to have activity on bindweed especially when tank mixed with other herbicides. This study was conducted to investigate the field performance and some physiological effects of metsulfuron on field bindweed. Neither metsulfuron alone nor metsulfuron combinations gave persistent control of field bindweed. Metsulfuron usually increased the activity of other bindweed herbicides. Herbicide application to field bindweed in the full bloom growth stage did not control the weed as well as the same treatments in the prebloom growth stages and treating regrowth the fall after tilling bindweed in full blossom. Application of metsulfuron at full bloom decreased seed weight, seed size seed viability and seedling vigor of field bindweed but did not alter seed set. Metsulfuron at 23 g/ha and above caused unacceptable injury to barley (Hordeum vulgaris L.) and oats (Avena sativa L.). Higher rates of metsulfuron resulted in greater phytotoxicity. Metsulfuron stopped photosynthesis of field bindweed within two weeks regardless of herbicide dosage used. Field bindweed seedlings were observed growing in the field under light intensities of 28 to 62 μmoles m-2 s-1 which was below the light compensation point obtained for greenhouse grown bindweed plants (about 65 μmoles m-2 s-1). Higher quantities of 14C labelled metsulfuron per mg plant dry weight were recovered in the above treated leaf sections than in any other parts of bindweed plants. Metsulfuron applied as a foliage spray two days prior to administering 14C metsulfuron significantly increased absorption to the radiolabelled herbicide in field bindweed plants

Competitive interaction between maize, Xanthium strumarium and Datura stramonium affecting some canopy characteristics

Abstract Field experiments were conducted in 2006 and 2007 to evaluate Xanthium strumarium and Datura stramonium single and multispecies interferences with maize. At different weed densities (4, 8, 12 and 16 plants m -2 ), X. strumarium and D. stramonium were planted in five proportions of 0:100, 25:75, 50:50, 75:25 and 0:100. Monoculture of maize at 6 plant m -2 and pure stands of X. strumarium and D. stramonium at two densities of 4 and 16 plants m -2 were also included. The results showed that X. strumarium is the most competitive weed in mixed plant community of maize, X. strumarium and D. stramonium. Maize, mainly due to its greater height at high density of weeds and because of its greater height and LAI at low density of weeds, was more successful in competition for light than the two weed species. At mixture of X. strumarium and D. stramonium under competition with maize, X. strumarium due to its greater LAI and height, showed greater ability in light interception than the other weed species. Therefore, stronger competitive ability of a weed in competition for light may be attributed to its canopy characteristics e.g. greater height and LAI expansion. In the mixed plant community, these characteristics enable the species to soon occupy the space and capture the common resources i.e. light. To control these weeds in maize, appropriate control measures have to be taken in early growth stages

Relationship between seed recovery and seed viability for data collected over four consecutive days.

<p>Relationship between seed recovery and seed viability for data collected over four consecutive days.</p

Time (as h after seed intake) to 50% mortality (half-life; <i>t</i>_<i>V</i>50, Eq 5) for four weed seeds passed through the digestive tract of four Holstein cattle groups (horizontal bars denote one standard error).

<p>Time (as h after seed intake) to 50% mortality (half-life; <i>t</i>_<i>V</i>50, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0154057#pone.0154057.e005" target="_blank">Eq 5</a>) for four weed seeds passed through the digestive tract of four Holstein cattle groups (horizontal bars denote one standard error).</p

Total recovered viable seeds (summed over four consecutive days) of the four weed seeds passed through the digestive tract of different groups of Holstein cattle (vertical bars denote one standard error).

<p>Total recovered viable seeds (summed over four consecutive days) of the four weed seeds passed through the digestive tract of different groups of Holstein cattle (vertical bars denote one standard error).</p

Changes in viability of the four weed seeds over time (as h after seed intake) for four groups of Holstein cattle.

<p>Symbols are observed data and lines are fitted values obtained from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0154057#pone.0154057.e004" target="_blank">Eq 4</a>.</p

Ingredients and chemical composition of the diet of four groups of Holstein cattle.

<p>Ingredients and chemical composition of the diet of four groups of Holstein cattle.</p

Relationship between seed viability and ruminal pH of four Holstein cattle groups.

<p>Relationship between seed viability and ruminal pH of four Holstein cattle groups.</p