Fall-applied Herbicides for Canada Thistle (Cirsium arvense) Root and Root Bud Control in Reduced-till Spring Wheat

1992 ◽  
Vol 6 (2) ◽  
pp. 252-261 ◽  
Author(s):  
William W. Donald

Several sequences of POST herbicides applied each year in fall alone, in spring alone, or both in fall and again in spring controlled Canada thistle stands in spring wheat by severely decreasing root biomass and the numbers of adventitious root buds to a depth of 50 cm over four years. These treatments included dicamba applied at 1.7 or 2.2 kg ae ha–1for the first two successive falls followed in wheat by either chlorsulfuron at 30 g ai ha–1plus nonionic surfactant, MCPA plus bromoxynil at 280 plus 280 g ha–1, or 2,4-D amine at 560 g ha–1applied annually for each of four consecutive years from the start. Chlorsulfuron at 30 g ha–1applied alone in spring for each of four years also reduced and prevented Canada thistle root growth as effectively as a sequence of fall-applied dicamba followed by spring-applied chlorsulfuron in spring wheat.

1988 ◽  
Vol 2 (4) ◽  
pp. 445-455 ◽  
Author(s):  
Steven J. Carlson ◽  
William W. Donald

Effects of repeated late-fall applications of the isopropylamine salt of glyphosate at 1.7 kg ae/ha plus 0.5% (v/v) surfactant on adventitious root buds, thickened propagative roots (> 1.3 mm diam), and shoot density of Canada thistle were studied in continuous hard red spring wheat over a 4-yr period. Glyphosate suppressed Canada thistle shoot density more quickly and to a greater extent than thickened root fresh weight or root bud number. A single fall application of glyphosate drastically decreased Canada thistle shoot density for 1 yr after treatment. However, shoot density was the same as the untreated control by 2 yr after a single fall treatment. Two consecutive late-fall applications of glyphosate in 2 yr decreased Canada thistle shoot density 94% in the fall 1 yr after the last treatment. Glyphosate reduced Canada thistle thickened root fresh weight 70% in the first fall 1 yr after a single fall treatment. However, 2 yr after a single fall application of glyphosate, root fresh weight equalled the controls. Two consecutive fall applications of glyphosate reduced thickened root fresh weight 77% 1 yr after the second treatment.


1987 ◽  
Vol 1 (2) ◽  
pp. 154-161 ◽  
Author(s):  
William W. Donald

Chlorsulfuron [2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-amino] carbonyl] benzenesulfonamide], applied at 9 to 560 g ai/ha to the soil surface, stopped shoot elongation of well established Canada thistle [Cirsium arvense(L.) Scop. #4CIRAR] plants in the greenhouse. Root fresh weight decreased progressively as chlorsulfuron rate was increased when measured 1 month after treatment. In contrast, the number of visible root buds plus secondary shoots increased 1.9- to 2.3-fold between 9 and 67 g/ha chlorsulfuron 1 month after soil surface treatment. Despite more numerous root buds, the number of secondary shoots arising from adventitious root buds progressively decreased as chlorsulfuron rate was raised. Increases in the number of visible root buds were observed first between 3 and 4 weeks following soil application with 67 g/ha of chlorsulfuron, 2 weeks after shoot growth stopped.


1993 ◽  
Vol 73 (1) ◽  
pp. 369-373 ◽  
Author(s):  
William W. Donald

Several methods were compared for estimating long-term control of Canada thistle [Cirsium arvense (L.) Scop.] after ending several years of herbicide treatment. Simple linear regression equations using shoot density m−2, numbers of adventitious root buds, or root fresh weight, measured in late summer after several years of herbicide treatment, were equally accurate in estimating Canada thistle shoot density m−2 in early June of the following year (R2 = 0.77–0.81). In contrast, shoot density m−2 measured in late summer estimated shoot density m−2 in late summer of the following year more accurately (R2 = 0.93) than did either root growth variable (R2 values = 0.80–0.83). Key words: Adventitious root buds, perennial weed, root


Weed Science ◽  
1988 ◽  
Vol 36 (6) ◽  
pp. 804-809 ◽  
Author(s):  
William W. Donald

The root fresh weight of intact Canada thistle plants was greater than that of decapitated plants 2 months following soil surface treatment with clopyralid at 140 g ai/ha. Nevertheless, secondary shoot regrowth potential was reduced to the same extent for both intact and decapitated plants after clopyralid treatment. Soil-applied clopyralid did not reduce root biomass as much as it reduced secondary shoot regrowth potential from adventitious root buds. Increasing the clopyralid rate from 11 to 1120 g/ha progressively reduced the total number of emerged shoots more than root fresh weight 2 months after treatment of decapitated Canada thistle. Increasing the clopyralid rate also reduced the regrowth potential of secondary shoots from root buds proportionately more than it reduced root biomass. Secondary shoots emerging through a surface layer of soil treated with clopyralid at 140 g/ha absorbed phytotoxic amounts of clopyralid. Secondary shoot numbers were not reduced after emerging through an activated charcoal layer into herbicide-treated soil, but they were deformed and their dry weight was reduced as was later secondary shoot regrowth potential.


Weed Science ◽  
1993 ◽  
Vol 41 (3) ◽  
pp. 434-440 ◽  
Author(s):  
William W. Donald

This field research was designed to compare the long-term effectiveness of late-September applications of several herbicides for reducing Canada thistle shoot density on noncropped, untilled abandoned farmland when reapplied annually for 3 yr. Clopyralid at 560 and 840 g ae ha−1or picloram at 280 and 560 g ae ha−1reduced Canada thistle shoot density as well as either glyphosate3at 0.8 to 2.8 kg ae ha−1or dicamba at 1.1 and 2.2 kg ae ha−1. These treatments were much more effective than 2,4-D at 1.1 and 2.2 kg ae ha−1, chlorsulfuron at 34 and 67 g ai ha−1, and metsulfuron at 34 and 67 g ha−1for progressively reducing Canada thistle shoot density over three annual fall applications. Picloram and clopyralid greatly reduced and delayed shoot emergence from adventitious root buds in spring after two fall-applied treatments compared with nontreated checks.


1992 ◽  
Vol 72 (2) ◽  
pp. 599-618 ◽  
Author(s):  
William W. Donald ◽  
Tony Prato

Several postemergence herbicides applied in fall for 2 yr either alone or followed by other spring-applied herbicides for 4 yr reduced densities of Canada thistle (Cirsium arvense (L.) Scop.) infesting reduced-till spring wheat (Triticum aestivum L.). However, fall-applied herbicides for 2 yr had little value for maintaining long-term Canada thistle control, unless supplemented by in-crop herbicide treatment. Neither fall-applied dicamba at 1.7 or 2.2 kg ha−1, glyphosate at 1.7 kg ha−1 plus nonionic surfactant, nor 2,4-D at 1.7 kg ha−1 applied each of 2 yr kept Canada thistle densities below that of the untreated check through year five. Spring-applied chlorsulfuron at 30 g ha−1 plus nonionic surfactant for each of four consecutive years reduced Canada thistle density in wheat to the same extent as fall-applied dicamba followed by chlorsulfuron applied in wheat. Fall herbicide treatments, with or without in-crop herbicide treatments, were economically risky and were seldom profitable. The relative ranking of farmer preference for five treatments common to two trials was similar: untreated check ≥ spring-applied chlorsulfuron at 30 g ha−1 ≥ fall-applied dicamba at either 1.7 or 2.2 kg ha−1 (rank reverses between trials 1 and 2) ≥ fall-applied dicamba at 2.2 kg ha−1 followed by spring-applied chlorsulfuron at 30 g ha−1. The only treatments that were preferred to the untreated check were both spring-applied 2,4-D at 560 g ha−1 and fall-applied 2,4-D at 1.7 kg ha−1 in trial 1 and both spring-applied (4-chloro-2-methylphenoxy) acetic acid (MCPA) plus bromoxynil 280 plus 280 g ha−1, respectively, and spring-applied 2,4-D plus clopyralid at 280 plus 70 g ha−1, respectively, in trial 2.Key words: Bromoxynil + MCPA, chlorsulfuron, dicamba, glyphosate, 2,4-D


Weed Science ◽  
1990 ◽  
Vol 38 (4-5) ◽  
pp. 379-384 ◽  
Author(s):  
Léonie B. Nadeau ◽  
William H. Vanden Born

We examined effects of supplementary nitrogen on young Canada thistle stands in Alberta, Canada. Urea applied at 70 or 100 kg N ha–1increased shoot population densities, mostly through increased root growth in the top 20 cm of soil rather than through released root bud dormancy. Nitrogen fertilization, therefore, may increase the severity of a Canada thistle infestation. In 1-yr-old stands, the number of emerged and unemerged root buds/m of root was higher near the soil surface in fertilized plots than in unfertilized plots, and no underground shoots were detected at the time of sampling. In 2-yr-old stands, more unemerged root buds/m of root were found at depths below 20 cm in fertilized plots than in unfertilized plots, and twice as many underground shoots/m of root occurred between 20 and 40 cm in fertilized plots as in unfertilized plots. However, no effect of nitrogen on the number of emerged root buds was detected. Nitrogen treatment increased shoot production only for those replanted root fragments from deeper than 60 cm in 1-yr-old stands and deeper than 160 cm in 2-yr-old stands.


Weed Science ◽  
1985 ◽  
Vol 33 (4) ◽  
pp. 524-530 ◽  
Author(s):  
Malcolm D. Devine ◽  
William H. Vanden Born

Both14C-clopyralid (3,6-dichloropicolinic acid) and14C-chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzensulfonamide} were readily absorbed by Canada thistle [Cirsium arvense(L.) Scop. ♯ CIRAR] leaves, with 99 and 75%, respectively, of the applied doses absorbed 144 h after application. Absorbed14C-clopyralid was rapidly exported from the treated leaves, whereas14C-chlorsulfuron was translocated much more slowly. After 144 h, 29% of the applied14C-clopyralid and 5% of the applied14C-chlorsulfuron were recovered in the roots and developing root buds of Canada thistle plants. Smaller amounts of the two herbicides were absorbed and translocated in perennial sowthistle (Sonchus arvensisL. ♯ SONAR) than in Canada thistle. More14C-clopyralid than14C-chlorsulfuron was absorbed and translocated out of treated leaves of perennial sowthistle, but equal amounts, 3 to 4% of the applied doses, were recovered in the roots and root buds 144 h after application. Foliar applications of clopyralid, followed by removal of the treated shoot 24, 72, or 144 h after application, markedly reduced shoot regrowth in both Canada thistle and perennial sowthistle. Similar treatment with chlorsulfuron did not prevent shoot regrowth in either species.


Weed Science ◽  
1984 ◽  
Vol 32 (1) ◽  
pp. 42-50 ◽  
Author(s):  
William W. Donald

The effect of 67 g ai/ha chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-amino] carbonyl] benzenesulfonamide} on Canada thistle [Cirsium arvense (L.) Scop. ♯ CIRAR] root bud growth was examined in a series of greenhouse trials in which potted plants were treated with foliar sprays. Injury to root buds was assayed by determining their ability to form secondary shoots. Added surfactant, 0.2% (v/v) oxysorbic [oxysorbic (20 POE) polyethylene sorbitan monooleate], did not enhance chlorsulfuron-induced inhibition of parent shoot growth, but it increased root bud injury from foliarly applied chlorsulfuron. Cuttings taken from controls formed more secondary shoots than did chlorsulfuron-treated plants 2 weeks following spraying. However, root fresh weight and final secondary shoot growth from cut roots were unchanged 3 weeks after chlorsulfuron treatment compared to the time of spraying. Foliar treatment or a combination of foliar and soil treatment inhibited root fresh weight accumulation and secondary shoot growth equally 1 month following treatment relative to harvest controls. Soil treatment alone did not reduce either root fresh weight gains or secondary shoot outgrowth from root buds. Foliar treatment of vegetative Canada thistle with chlorsulfuron inhibited subsequent secondary shoot outgrowth from root buds more than did treatment at flowering.


Weed Science ◽  
1985 ◽  
Vol 33 (2) ◽  
pp. 148-152 ◽  
Author(s):  
Ray S. McAllister ◽  
Lloyd C. Haderlie

Adventitious root bud development and assimilate translocation were studied in Canada thistle [Cirsium arvense(L.) Scop. ♯ CIRAR] grown in nutrient solution in controlled environments using combinations of two photoperiods (PP) (13 and 15 h), three day/night shoot temperatures (ST) (15/5, 25/15, and 30/22 C), and three root temperatures (RT) (10, 20, and 30 C). Total root bud elongation increased with RT and length of PP and was greatest (65 cm/plant) at 25/15 C ST, 15-h PP, and 30 C RT. The number of root buds produced was greatest at 20 C RT (7.3 to 10.3 buds/plant), whereas variations in PP and ST had little effect. Total dry-matter production was greatest (7.2 g/plant) at 15-h PP, 30/22 C ST, and 20 C RT. To study phloem translocation, photoassimilates were labeled in Canada thistle plants by exposing mature leaves to14CO2. Net assimilate translocation from a source leaf following 24-h temperature acclimation was affected little by RT and ST, but was greater under the 13-h PP than under the 15-h PP. After 7 days of temperature preconditioning, net translocation of14C-assimilates increased with both RT and ST, but no effects due to PP were noted. With 24-h temperature acclimation, net assimilate accumulation in roots was enhanced by 13-h PP and low ST (15/5 C), whereas RT itself had no effect. In temperature-preconditioned plants, 10 C RT enhanced assimilate accumulation in roots, but ST and PP had no effect.


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