Integrated Management of Scotch Broom (Cytisus scoparius) Using Biological Control

Abstract

Integrated weed management strategies (IWM) are being advocated and employed to control invasive plants species. In this study, we compared three management strategies (biological control alone [BC], BC with fire [BC + F], and BC with mowing [BC + M]) to determine if physical controls reduce seed production by Scotch broom and interfere with the action of the biological control agent—the Scotch broom seed weevil. We measured seed production and seed predation by the weevil at both pod and plant scale, and seed bank density over two field seasons. We found no difference in the number of seeds per pod among management strategies. However, combining management strategies (BC + M and BC + F) resulted in significant reductions in pods per plant, mature seeds per plant, and seed bank density relative to biological control alone. We did not find differences among management strategies in number of weevils per pod or proportion of seeds predated by the weevil at either pod or whole-plant scale. However, combining management strategies (BC + M and BC + F) resulted in a significant reduction in healthy mature seeds per plant relative to biological control alone. Although both integrated strategies outperformed biological control alone in reducing seed production and the seed bank, with no statistical difference between them, we propose that short-rotation prescribed fire could prove to be a more effective strategy for long-term management of Scotch broom due to its potential for slightly greater depletion of the seed bank.

Patterns of Growth Costs and Nitrogen Acquisition in Cytisus striatus (Hill) Rothm. and Cytisus balansae (Boiss.) Ball are Mediated by Sources of Inorganic N

“…Cytisus striatus (Hill) Rothm. is a shrubby legume endemic to the Iberian Peninsula that has colonized other parts of the world [ 28 ]. It grows in siliceous soils from 450–750 m a.s.l., avoiding cold distributions.…”

Seed Dispersers, Seed Predators, and Browsers Act Synergistically as Biotic Filters in a Mosaic Landscape

“…Consequently, post-dispersal seed predation has the potential to filter the species pool available for recruitment of the woody community in a similar way in all landscape units, irrespective of the degree of degradation, reducing the number of propagules of dominant tree species and favouring further a shrub-like landscape, which is the type of landscape unit where rodents can find both food and refuge [26], [37]. Although we do not have data on seed predation in dry-fruited shrubs (mainly ballistic dispersal) in our study area, other studies indicate that their predation is much lower than for tree species, and are especially depredated by weevils before dispersal and by ants afterwards [38]–[41].…”

Comparison of Allergenicity of Mature Pollen Grains and Petals in Two Ontogenic Stages in Cytisus scoparius L.

“…Since seasonal sensitivities increase in the spring and allergic reactions occur in sensitive people, especially children and the elderly, investigating allergenicity of the pollen grains and aromatic petalsin plants that pollinatein the spring is necessary. Because the pollen grains of this plant are carried by bumblebees and wasps (21,24), it is possible that pollen grains containing allergen compounds used in honey production can enter the human body (8,25). Our research in 2014, showed allergenicity petals of old ontogenical (26).…”

“…This beautiful and extremely fragrant flower is native to Europe and North Africa and has subsequently spread to Asia (18)(19)(20). The flowering period is between the months of May and June (19)(20)(21)(22)(23)(24). Since seasonal sensitivities increase in the spring and allergic reactions occur in sensitive people, especially children and the elderly, investigating allergenicity of the pollen grains and aromatic petalsin plants that pollinatein the spring is necessary.…”