Effect of weed control methods on growth of five temperate agroforestry tree species in Saskatchewan

Abstract

Most tree species in agroforestry plantings are intolerant to vegetative competition and sites must be intensively cultivated to eliminate weeds. Many studies have been conducted to investigate what factors limit seedling growth because of the presence of vegetative competition in forest environments; however on agricultural sites there are few studies on weed management options for tree planting. This research quantified and compared growth of Manitoba maple (Acer negundo), green ash (Fraxinus pennsylvanica), Colorado spruce (Picea pungens), Scots pine (Pinus sylvestris) and Walker poplar (Populus x Walker) in response to combinations of in-row and between-row weed control methods. The study was established on an agroforestry planting on agricultural soils in Saskatchewan. Treatments included in-row weed control using herbicides or plastic mulch and between-row weed control using tillage compared with a non-weeded control. Weed control positively affected annual height increment, basal diameter and height of the agroforestry species. The impacts of weed control versus no weed control were significant in almost all instances. However, tree species responded differently to the method of weed control. Weed control by herbicide and plastic mulch were not significantly different for four of the five species under investigation. This research will help with prescribing weed control methods for agroforestry and afforestation plantings on agricultural soils.Key words: weed control, agroforestry, tree growth, plastic mulch, tillage, herbicide RÉSUMÉLa plupart des essences plantées en agroforesterie tolèrent mal la végétation compétitive et il faut donc effectuer un travail intensif du sol sur ces sites pour en éliminer les mauvaises herbes. Pour le milieu forestier on dénombre plusieurs études sur les facteurs qui affectent la croissance des semis lorsqu'ils sont soumis à une compétition végétale; en milieu agricole, les études se font toutefois plus rares sur les moyens pour contrôler les mauvaises herbes en plantation. Ce projet aura permis de quantifier et de comparer la croissance de l' érable négondo (Acer negundo), du frêne vert (Fraxinus pennsylvanica), de l' épinette du Colorado (Picea pungens), du pin d'Écosse (Pinus sylvestris) et du peuplier hybride Walker (Populus x Walker) en réponse à diverses combinaisons de méthodes de désherbage dans les rangées de plants et entre celles-ci. Le dispositif d' étude a été établi dans une plantation agroforestière sur des terres agricoles de la Saskatchewan. Les traitements comprenaient un désherbage dans les rangées à l'aide d'herbicides ou de paillis de plastique, un travail du sol entre les rangées et enfin un témoin sans désherbage. Le désherbage a eu un effet positif sur la croissance annuelle en hauteur, la surface terrière et la hauteur des espèces agroforestières. Le désherbage a eu un impact significatif dans presque tous les cas en comparaison avec la situation sans traitement. Toutefois, les essences forestières n' ont eu les mêmes réac-tions aux divers ...

Black Plastic Mulch or Herbicide to Accelerate Bur Oak, Black Walnut, and White Pine Growth in Agricultural Riparian Buffers?

“…Hardwood species had the strongest growth response to the vegetation treatments and white pine had the weakest (Figures 4 and 5), which supports our second hypothesis and previous observations made in a nearby riparian buffer and in agroforestry systems of the Prairies [15,30]. In fact, stem volume, height, and diameter growth were not statistically different between the three vegetation treatments for white pine ( Figure 5).…”

“…However, despite the more favorable growth conditions provided by the mulch, the growth of all species was not statistically different between the herbicide and the mulch treatments ( Figure 5, Table 4). In the Canadian Prairies, herbicide and plastic mulch also provided similar growth gains for four-year-old agroforestry trees belonging to various genera [30].…”

Survival and Growth Response of Four Agroforestry Species to Post Planting Management Regimes

“…Besides, controlling weed signi cantly affected height and diameter of tree species (Naeem, and Schroeder, 2017). Weeds compete for light, moisture, and nutrients and thus, removal of weeds through frequent hoeing is essential for good early growth of seedlings (Vollmann et.al., 2010andRabbani et.al., 2011.Unless regular weeding is ensured, lapse in controlling weed during early stages of establishment caused reductions in growth and establishment of tree species (Alwi et al, 2020).…”

Assessment of a Chain Mower Performance for Weed Control under Tree Rows in an Alley Cropping Farming System

“…Schroeder and Naeem [12] observed that weed control positively influenced the annual height increment, total basal diameter, and height of the tested agroforestry tree species. Furthermore, the risk that some weeds spread from the under-row area towards the crop in the alley, leading to yield losses, should be considered [13][14][15].…”

“…Nevertheless, the proliferation of vegetation can create a too-competitive environment for the establishment and growth of trees [19]. On the other hand, the application of chemicals (i.e., herbicides), despite their effectiveness, not only causes environmental pollution but can also damage trees, making it necessary to shield them before treatments [12,16]. Mowing represents another weed control method commonly adopted in alley cropping systems.…”