Longspine Sandbur Research Articles

Rye Living Mulch Effects on Soil Moisture and Weeds in Asparagus

Living mulches growing below asparagus (Asparagus officinales) fern can improve soil health and suppress weeds but may also suppress asparagus through competition for water or nutrients. The central objective of this research was to test whether cereal rye (Secale cereale) living mulch, in combination with overhead irrigation, could provide comparable weed suppression to standard residual herbicides without reducing asparagus yields. A field experiment was conducted from 2008 to 2010 in a mature asparagus planting on sandy soils in western Michigan to evaluate the effects of irrigation (none vs. overhead) and weed management systems (standard herbicides vs. rye living mulch) on weed suppression, soil moisture content, and asparagus yield. Rye living mulch and herbicide treatments were established immediately after asparagus harvest in late June of each year. Rye living mulch reduced soil-available water in early August by 26% to 52% compared with herbicide treatments but had no detectable effect on asparagus yields. Compared with herbicide treatments, rye living mulch reduced fall-germinating weed emergence and resulted in lower densities of horseweed (Conyza canadensis) during asparagus harvest. However, in 2 of 3 years, the living mulch system resulted in higher densities of summer annual weeds—including Powell amaranth (Amaranthus powellii) and longspine sandbur (Cenchrus longispinus)—during the fern growth period compared with herbicide treatments. After 3 years, the density of summer annual weeds was more than 10-fold greater in rye living mulch treatments compared with standard residual herbicides treatments. Our results suggest that 1) soil-improving rye cover crops can partially suppress weeds but may also compete with asparagus for soil moisture in dry years unless irrigation is used; and 2) successful use of rye living mulches for weed management will depend on identification of complementary weed management practices to avoid build-up of the summer annual weed seedbank.

Response of Barnyardgrass (Echinochloa crus-galli), Green Foxtail (Setaria virdis), Longspine Sandbur (Cenchrus longispinus), and Large Crabgrass (Digitaria sanguinalis) to Nicosulfuron and Rimsulfuron

Experiments were conducted to determine the efficacy, absorption, and translocation of nicosulfuron, rimsulfuron, and nicosulfuron + rimsulfuron on barnyardgrass, green foxtail, longspine sandbur, and large crabgrass. In the greenhouse, nicosulfuron, rimsulfuron, and nicosulfuron + rimsulfuron were applied at 0.0625, 0.125, 0.25, 0.5, 0.75, 1, and 2 times their label rates of 35, 13, and 26 + 13 g ai ha−1, respectively, on 5- to 10-cm plants. Three weeks after treatment (WAT), barnyardgrass was the most susceptible species to all three herbicides, and large crabgrass was the least susceptible. The nicosulfuron, rimsulfuron, or nicosulfuron + rimsulfuron rates causing 50% visible injury (GR50) for barnyardgrass were 10.9, 4.8, and 6 + 3 g ai ha−1, respectively. Similarly, the GR50for large crabgrass were 25.6, 9.9, and 14.3 + 7.2 g ai ha−1, respectively, 3 WAT. Absorption of nicosulfuron, rimsulfuron, and nicosulfuron + rimsulfuron was greater in barnyardgrass than in large crabgrass. Absorption of nicosulfuron + rimsulfuron in barnyardgrass and large crabgrass was 74% and 57%, respectively, 7 d after treatment (DAT). In addition, translocation of nicosulfuron, rimsulfuron, and nicosulfuron + rimsulfuron out of the treated leaf was 14, 12, and 14% higher, respectively, in barnyardgrass than in large crabgrass. The differential response of these weed species to nicosulfuron, rimsulfuron, and nicosulfuron + rimsulfuron might be due to differences in herbicide absorption and translocation.

Long-spine sandbur [Cenchrus longispinus (Hack. in Kneuck.) Fernald] control in corn

Long-spine sandbur is an annual grass that infests many fields in southwestern Ontario, especially those with sandy soils. Eight field experiments were conducted over a 2-yr period (2007, 2008) in Ontario to determine the efficacy of various preemergence (PRE) and postemergence (POST) herbicides for control of long-spine sandbur in corn. Generally, the POST applied herbicides controlled long-spine sandbur better than PRE herbicides evaluated in this study. PRE application of dimethenamid-p (1250 g a.i. ha-1), S-metolachlor (1600 g a.i. ha-1), flufenacet (1040 g a.i. ha-1), pendimethalin (1680 g a.i. ha-1), pyroxasulfone (250 g a.i. ha-1), or isoxaflutole plus atrazine (105 + 1063 g a.i. ha-1) controlled long-spine sandbur 0-79%. POST application mesotrione + atrazine (140 + 280 g a.i. ha-1) or topramezone + atrazine (18.75 + 500 g a.i. ha-1) provided 24-82% control, foramsulfuron (35 g a.i. ha-1) or primisulfuron/dicamba (26 +140 g a.i. ha-1) provided 54-87% control, and rimsulfuron (15 g a.i. ha-1), nicosulfuron (25 g a.i. ha-1) or nicosulfuron/rimsulfuron (25 g a.i. ha-1) provided 68-95% control of long-spine sandbur in corn. Similar reduction in sandbur density and shoot dry weight were observed. PRE applied isoxaflutole + atrazine and POST applied rimsulfuron, nicosulfuron, nicosulfuron/rimsulfuron, foramsulfuron, primisulfuron/dicamba, and topramezone + atrazine all provided yield comparable with the weed-free control. Among the herbicides evaluated rimsulfuron, nicosulfuron, and nicosulfuron/rimsulfuron provide the most consistent long-spine sandbur control in corn.Key words: Weed control, preemergence herbicide, postemergence herbicide, rimsulfuron, nicosulfuron, foramsulfuron, primisulfuron, dicamba, topramezone, atrazine

Glyphosate-Induced Weed Shifts in Glyphosate-Resistant Corn or a Rotation of Glyphosate-Resistant Corn, Sugarbeet, and Spring Wheat

A field trial was conducted for 6 yr (1998 through 2003) at Scottsbluff, NE, to measure weed shifts following multiple applications of two rates of glyphosate or alternating glyphosate with nonglyphosate treatments in continuous corn or in a crop rotation of corn, sugarbeet, and spring wheat with all three crops resistant to glyphosate. After 6 yr, plant densities of common lambsquarters, redroot pigweed, hairy nightshade, and common purslane increased in the crop-rotation treatment compared with continuous corn. There were four weed control subplot treatments consisting of two in-crop applications of glyphosate at 0.4 or 0.8 kg ae/ha each spring, alternating two applications of glyphosate at 0.8 kg/ha one year with a nonglyphosate treatment the next year, or a nonglyphosate treatment each year. The composition of the weed population averaged across all four treatments shifted from kochia and wild proso millet to predominately common lambsquarters. After 3 yr of using glyphosate at 0.4 kg/ha twice each year, common lambsquarters density increased compared with that in the 0.8 kg/ha rate of glyphosate or alternating glyphosate treatments. By the sixth year, the density of common lambsquarters in the glyphosate at 0.4 kg/ha treatment had increased to the extent that corn grain yield was reduced 43% compared with corn grain yield in the 0.8 kg/ha glyphosate treatment. Using glyphosate at either rate for 6 yr decreased the densities of kochia, wild proso millet, and longspine sandbur, did not alter densities of redroot pigweed and green foxtail, and increased the density of hairy nightshade. In the low-rate treatment of glyphosate, the number of common lambsquarters seeds in the seed bank were 134 seeds/kg soil in 1998, declined to 15 seeds/kg by 2002, but began to increase in 2003 as the densities of plants not controlled by glyphosate increased.

KIH-485 and S-metolachlor Efficacy Comparisons in Conventional and No-Tillage Corn

Field experiments were conducted during 2003 and 2004 to compare the effectiveness of KIH-485 and S-metolachlor for PRE weed control in no-tillage and conventional-tillage corn. Longspine sandbur control increased as KIH-485 or S-metolachlor rates increased in conventional-tillage corn, but control did not exceed 75% when averaged over experiments. Both herbicides controlled at least 87% of green foxtail with the exception of no-tillage corn in 2004, when KIH-485 was more effective than S-metolachlor at lower rates. Palmer amaranth control ranged from 85 to 100% in 2003 and 80 to 100% in 2004, with the exception of only 57 to 76% control at the lowest two S-metolachlor rates in 2004. Puncturevine control exceeded 94% with all treatments in 2003. In 2004, KIH-485 controlled 86 to 96% of the puncturevine, whereas S-metolachlor controlled only 70 to 81%. Mixtures of atrazine with KIH-485 or S-metolachlor generally provided the most effective control of broadleaf weeds studied.

Survey of Winter Wheat (Triticum aestivum) Stubble Fields Sprayed with Herbicides in 1998: Weed Control1

A survey of 174 fields was conducted to investigate performance of herbicides applied after winter wheat harvest on weeds across western and southern Nebraska during August and September 1998. Glyphosate plus 2,4-D plus atrazine was applied on 32%, glyphosate plus 2,4-D or dicamba on 24%, paraquat plus atrazine on 23%, glyphosate on 8%, ICIA0224 plus 2,4-D or atrazine on 10%, and atrazine plus 2,4-D on 3% of the fields. These treatments controlled 85 to 100% of the weeds except atrazine plus 2,4-D, which controlled 30%. The frequency of occurrence of the most prevalent summer annual grasses was as follows: green foxtail, 65%; barnyardgrass, 46%; stinkgrass, 41%; witchgrass, 39%; and longspine sandbur, 36%. The most common broadleaf weeds and their frequency were redroot pigweed, 32%; tumble pigweed, 30%; tall waterhemp, 28%; and kochia, 25%. Virginia groundcherry, 22%; common milkweed, 11%; yellow woodsorrel, 9%; and field bindweed, 6% were the most common perennial weeds. The five most difficult weeds to control were yellow nutsedge, spotted spurge, Virginia groundcherry, common milkweed, and toothed spurge, with control ratings of 0, 3, 17, 26, and 33%, respectively. These weeds were not controlled with glyphosate or mixtures containing glyphosate. Only 35% of the fields were treated before summer annual grasses had headed. Late applications required higher herbicides rates for effective control.Nomenclature: Atrazine; 2,4-D; dicamba; glyphosate; ICIA0224 (glyphosate trimethylsulfonium salt); paraquat; barnyardgrass, Echinochloa crus-galli (L.) Beauv. #3 ECHCG; common milkweed, Asclepias syriaca L. # ASCYS; field bindweed, Convolvulus arvensis L. # CONAR; green foxtail, Setaria viridis (L.) Beauv. # SETVI; kochia, Kochia scoparia (L.) Schrad # KCHSC; longspine sandbur, Cenchrus longispinus (Hack.) Fern. # CCHPA; redroot pigweed, Amaranthus retroflexus L. # AMARE; spotted spurge, Euphorbia maculata L. # EPHMA; stinkgrass, Eragrostis cilianensis (All.) E. Mosher # ERACN; tall waterhemp, Amaranthus tuberculatus (Moq.) J. D. Sauer # AMATA; toothed spurge, Euphorbia dentata Michx. # EPHDE; tumble pigweed, Amaranthus albus L. # AMAAL; Virginia groundcherry, Physalis virginiana Mill. # PHYLC; witchgrass, Panicum capillare L. # PANCA; yellow nutsedge, Cyperus esculentus L. # CYPES; yellow woodsorrel, Oxalis stricta L. # OXAST; winter wheat, Triticum aestivum L.Additional index words: AMAAL, AMARE, atrazine, conservation tillage, CYPES, 2,4-D, dicamba, ECHCG, ecofallow, ecofarming, ERACN, glyphosate, KCHSC, KSHSC, no-till, OXAST, PANCA, paraquat, SETVI, weed management.

Longspine Sandbur (Cenchrus longispinus) Ecology and Interference in Irrigated Corn (Zea mays)

Longspine sandbur is a troublesome weed infesting corn in the Great Plains. However, herbicides are now available to control this species. This study characterized longspine sandbur ecology in irrigated corn to aid producers in integrating herbicides into their production systems. Longspine sandbur began emerging May 25, and by June 15, 84% of the seasonal emergence had occurred. Plant development was related to cumulative growing degree days. Seeds were viable early in longspine sandbur's development, with 20% of seeds viable by heading. Producers can minimize seed production of longspine sandbur in field borders by mowing plants at the boot stage. Bur production per plant was related to time of emergence, with seedlings emerging in late May producing 1,120 burs per plant. Seedlings emerging 4 wk later produced 84% fewer burs. Controlling longspine sandbur before 4 wk of interference prevented loss of corn grain yield.

Rapeseed (Brassica napus) Green Manure Crop Suppresses Weeds in Potato (Solanum tuberosum)

Fall-planted rapeseed and sudangrass were evaluated for weed control in potato during a two-year study. Rapeseed incorporated in the spring in a loamy sand soil reduced weed density 85 and 73% in 1992 and 1993, respectively, and reduced weed biomass 96 and 50% in 1992 and 1993, respectively, in following potato crops compared to potato after fallow. Potato following rapeseed yielded 25% and 17% more total tuber weight than potato following sudangrass in 1992 and fallow in 1993, respectively. In greenhouse trials, rapeseed tissue added to a loamy sand soil at 20 g fresh weight per 400 g dry soil reduced biomass of hairy nightshade and longspine sandbur by 90 and 83%, respectively. Similarly, white mustard tissue added at 20 g fresh weight per 400 g dry soil reduced biomass of hairy nightshade and green foxtail by 83 and 70%, respectively.

Effect of Preplant Tillage, Post-Plant Cultivation, and Herbicides on Weed Density in Corn (Zea mays)

A four-year experiment was conducted near Scottsbluff, NE to evaluate the effect of different methods of preplant tillage, post-plant cultivation, and herbicides on weed density and grain yield. Ridge-till enhanced the development of kochia and reduced the density of wild proso millet and common lambsquarters. Tandem disking increased longspine sandbur and redroot pigweed density whereas moldboard plowing increased common sunflower density. Cultivation reduced weed density 86% but weeds that remained after cultivation reduced corn grain yield by 40% as compared with a hand-weeded control. Weed control treatments that integrated cultivation and herbicides controlled a broader spectrum of weed species than cultivation or herbicide treatments alone.

Time of Emergence and Seed Production of Longspine Sandbur (Cenchrus longispinus) and Puncturevine (Tribulus terrestris)

Fall-planted longspine sandbur began to emerge in April, peaked in late April or May, and continued at low levels through October. During the first year after seeding, 98% of the total seedlings emerged prior to June. Fall-planted puncturevine began to emerge in late April or May and continued through October. Puncturevine emergence was multipeaked and 75% of each season's total emerged prior to mid-July. A similar number of puncturevine seedlings emerged the second and third years after planting as in the first. The emergence pattern for a species was similar each year regardless of how long the seed had lain in the soil. Longspine sandbur required 7 to 13 weeks from emergence to heading and produced approximately 2600, 1300, 180, and 3 spikes per plant when planted in May, June, July, and August, respectively. Puncturevine flowered within 3 to 4 weeks after emergence when temperatures were favorable and produced an average of 5600, 5200, 3600, and 200 burs per plant when planted in May, June, July, and August, respectively.

Germination and Emergence of Longspine Sandbur (Cenchrus longispinus)

Longspine sandbur germinated readily after 3 months of storage at 0 to 4 C. Germination was 15 to 82 and 10 to 76% for seed retained by or that passed through a 1.7-mm-mesh screen, respectively, and was greatest in complete darkness near 30 C. Light inhibited seed germination at most of the temperatures tested. Incubating imbibed seed at 40 C and 40/10 C for 3 weeks reduced the viability of seed that did not germinate by more than 50%. Primary seed within the bur germinated 77% and secondary seed germinated 35% during 2 weeks at 35/10 C (16 light/8 dark h). Primary seed placed in polyethylene glycol (PEG) solutions ranging from −0.5 to −1.5 kPa water potential germinated as much or greater than seed placed in water, while secondary seed germination was inhibited by similar osmotic potentials. Seedlings emerged from depths to 11 cm but emerged most readily from 1- to 3-cm depths.

Selectivity Mechanisms for Foliar Applications of Diclofop-methyl. II. Metabolism

The fate of foliarly applied14C diclofop-methyl {methyl 2-[4-(2,3-dichlorophenoxy)phenoxy] propanoate} was determined in intact plants of barnyardgrass [Echinochloa crus-galli(L.) Beauv.], a susceptible (S) grass; proso millet (Panicum miliaceumL.), a moderately susceptible (MS) grass; longspine sandbur [Cenchrus longispinus(Hack.) Fern.], a tolerant (T) grass; soybean [Glycine max(L.) Merr. ‘Hark’], and cucumber (Cucumis sativusL. ‘Green Star’), both T broadleaf plants, 1,3, and 5 days after treatment (DAT). Diclofop-methyl accounted for 94% of the radioactivity washed from the leaf surfaces of all species. Plant extracts contained diclofop-methyl, diclofop, and water-soluble conjugates. Barnyardgrass (S), proso millet (MS), and soybean (T) had 75, 68, and 66% of the extracted radioactivity as diclofop and diclofop-methyl. Longspine sandbur (T) and cucumber (T) had 71 and 84% of the extracted radioactivity as water-soluble conjugates. Acid hydrolysis of the water-soluble conjugates yielded 84 and 71% diclofop in barnyardgrass (S) and proso millet (MS). Cucumber (T), soybean (T), and longspine sandbur (T) had 43, 23, and 25% ring-OH diclofop. Alkaline hydrolysis of the non-extracted plant residue yielded diclofop as the major component in all species.

Selectivity Mechanisms for Foliar Applications of Diclofop-Methyl. I. Retention, Absorption, Translocation, and Volatility

Retention, absorption, translocation, and volatility of foliarly applied diclofop-methyl {methyl 2-[4-(2,4-dichlorophenoxy) phenoxy] propanoate} were compared in barnyardgrass [Echinochloa crus-galli(L.) Beauv.], a susceptible grass; proso millet (Panicum miliaceumL.), a moderately susceptible grass; longspine sandbur [Cenchrus longispinus(Hack.) Fern.], a tolerant grass; and soybean [Glycine max(L.) Merr. ‘Hark’] and cucumber (Cucumis sativusL. ‘Green Star’), both tolerant broadleaf plants. On a jug/plant basis, the order of diclofop-methyl spray retention was cucumber > soybean > proso millet > longspine sandbur = barnyardgrass. On a μg/mg dry weight basis, proso millet retained 3 to 10 times more diclofop-methyl than all other species. One day after treatment (DAT), absorption of14C-diclofopmethyl was 14 to 18% less in longspine sandbur than in the other species, 3 DAT absorption in cucumber was 8 to 14% greater than in the other species, and 5 DAT absorption in soybean was 3 to 12% less than in other species. Translocation of14C-diclofop-methyl did not differ among species, with 98% of the applied radioactivity located in the treated leaf. An average of 11% of radioactivity applied to the surface of intact, living plants and excised, dried leaves of cucumber, soybean, and barnyardgrass, as well as glass cover slips, was lost by evaporation. None of the parameters measured showed differences large enough to be implicated as primary selectivity mechanisms.