Suppression of Knapweed Invasion by Crested Wheatgrass in the Dry Interior of British Columbia

Berube, D. E.; Myers, Judith H.

doi:10.2307/3898605

Cited by 46 publications

(23 citation statements)

References 4 publications

(4 reference statements)

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“…However, after several years, there has been a decline in the number of capitula and seed production has dropped from over 40,000 per square metre to an average of just over 3000 per square metre in (Harris 1991. Berube and Myers (1982) suggested that control might now be achieved by establishing a strong competitor of knapweed, such as crested wheatgrass. Without competition, Schirman (1981) found that knapweed seed reduction would have to be over 99.9% to achieve control.…”

Section: Biocontrol Valuementioning

confidence: 99%

Effectiveness of Gall Inducers in Weed Biological Control

Harris

Shorthouse

1996

Can Entomol

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Abstract:Gall inducers are favoured as biocontrol agents of weeds because they tend to have a narrow host range. Six insect and one nematode gall inducer used in Canada are described in terms of their biology, gall morphology, gall physiology, and effectiveness in weed control. The species differ in plant organ attacked, requirement for moisture, whether the galls are induced by secretions or by severing xylem, and effectiveness, which in part relates to the ability of the gall to import nutrients. The most powerful galls divert assimilates from other sinks via a gall's vascular system joined to that of their host. One of our examples also has mechanisms to compensate for reduction of turgor during drought. Two of the gall inducers enhance their nutrient supply by severing xylem in a plant nutrient sink. One, in the short-term sink of a thistle capitulum, obtains about a quarter of its assimilates at the expense of other capitula. The other, in the long-term sink of a rosette root, approximately halves seed production. Hypotheses are presented to explain various aspects of gall development and function.

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Section: Biocontrol Valuementioning

confidence: 99%

Effectiveness of Gall Inducers in Weed Biological Control

Harris

Shorthouse

1996

Can Entomol

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“…Disturbance aids in establishment of knapweed (Hobbs and Huenneke 1992). Once established, spotted knapweed is persistent and can tolerate low nutrient soils (Suding et al 2004;LeJeune et al 2006), drought (Berube and Myers 1982), and produce a seed bank with seeds viable for at least 8 years (Davis et al 1993).…”

Section: Introductionmentioning

confidence: 99%

Is spotted knapweed (Centaurea stoebe L.) patch size related to the effect on soil and vegetation properties?

Fraser

Carlyle

2010

Plant Ecol

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Spotted knapweed (Centaurea stoebe L. subsp. Micranthos (Gugler) Hayek) was first introduced in the 1890s from Europe into western North America, where it now occupies over three million hectares of rangeland and pasture in 14 states and two Canadian provinces, reducing forage production and causing economic damage. Despite many reported effects spotted knapweed can have on soils and native vegetation, it is not known whether patch size is correlated with these ecosystem-level effects. The objective of our study was to determine whether the effects of spotted knapweed on plant composition and soil properties was related to spotted knapweed patch size. We asked the following questions: (1) Are there differences in plant species richness and diversity between small and large knapweed patches? and (2) Do soil water and soil mineral nutrient properties change depending on knapweed patch size? Twentyfour knapweed patches, and paired natural grassland plots, were randomly selected within Lac du Bois Provincial Park, British Columbia, Canada. Knapweed patch size ranged from 6 to 366 m2. Sampling and analysis revealed a significant effect of knapweed patch size on soil and vegetation properties. Soil P, soil temperature, and total dry plant biomass (g/0.25 m2) increased, while soil N, soil C, and soil moisture decreased with patch size. Since our results show that spotted knapweed patch size is related to degree of soil alteration, it is important to consider size of patch when modeling the impact of spotted knapweed in North America. Since large patches of spotted knapweed seem to have a proportionately greater effect on soil chemistry properties, large patches may move the system further away from a point where it is possible to restore the site to pre-invasion conditions.Peer reviewedGrasslandsRangelandsInvasive plantPlant diversityPlant litterSoil nutrient

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“…Berube and Myers (1982) observed two to four times more diffuse knapweed seedlings and rosettes in plots that had been physically disturbed compared to undisturbed plots.…”

Section: Discussionmentioning

confidence: 90%

Diffuse knapweed (Centaurea diffusa Lam.) seedling emergence and establishment in a Colorado grassland

2009

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Knapweeds (Centaurea spp.) are damaging invaders of grasslands and other North American rangelands. A field study was conducted to determine conditions that promote diffuse knapweed (C. diffusa) emergence and establishment in a native Colorado grassland (North America). Knapweed was planted in native grassland under treatments with different opening sizes, levels of competition, knapweed seed burial and season of seeding. There was no effect of opening size where competing natives were alive, but knapweed emergence in 5-and 15-cm openings was higher than 0-cm openings where natives were killed. Reducing competition reduced fall diffuse knapweed emergence, but did not affect spring emergence. Seed burial increased knapweed emergence, but the effect varied by season. Although diffuse knapweed emergence reached 35%, only four plants survived from 3,600 seeds. This native grassland did not prevent knapweed emergence or establishment, but both were so low that rapid knapweed invasion is unlikely.

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Suppression of Knapweed Invasion by Crested Wheatgrass in the Dry Interior of British Columbia

Cited by 46 publications

References 4 publications

Effectiveness of Gall Inducers in Weed Biological Control

Effectiveness of Gall Inducers in Weed Biological Control

Is spotted knapweed (Centaurea stoebe L.) patch size related to the effect on soil and vegetation properties?

Diffuse knapweed (Centaurea diffusa Lam.) seedling emergence and establishment in a Colorado grassland

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