Economic Importance of Weeds: A Review

Abstract

Weeds are plants that are unwanted in a given situation and may be harmful, dangerous or economically detrimental. They are responsible for substantial losses of farm production and extensive damage to the environment. Weeds, through competition with other plants, would almost always have deleterious effects on them and can have a lethal effect on livestock through consumption of weeds containing poisonous chemicals in the pasture. Weed invasion has become the most dreaded and deleterious impact of weeds in nature; it adversely affects agriculture, alters the balance of ecological communities, disrupts the natural diversity and interferes in the aesthetic value of the environment. Weeds can interfere in water management, thereby reducing the economic value of water. Weeds, however, besides their deleterious impacts in nature, have many beneficial properties, which include, but not limited to benefits of weeds to companion plants, ethnomedical and ethnopharmaceutical uses of weeds, ethnobotanical uses of wild edible weeds, and the use of weeds as feed for livestock. In the light of myriads of deleterious effects and benefits accompanying weeds, it is suggested that more studies should be carried out on weed control and weed management. Also, further explorations on the potential uses of weeds to man, his environments and livestock should be undertaken.

Detection and mapping of Amaranthus spinosus L. in bermudagrass pastures using drone imagery and deep learning for a site‐specific weed management

“…High pressure of weed encroachment negatively affects pasture productivity mainly because of competition for limited resources including nutrients, water, and light (Herbin et al., 2020). In grazing systems, weed encroachment can impose costs through weed control, reducing herbage allowance, stocking rates, and cattle performance (Ekwealor et al., 2019). Additionally, the health and performance of animals may be impacted by poisonous components or injuries from spines (Ekwealor et al., 2019; Ghanizadeh & Harrington, 2019).…”

Effects of Weed Control Methods on Weeds and Productivity of Range Grasses in Semi-Arid Kenya

“…In East Africa, large tracts of land in semi-arid areas are infested with weeds which compete with favorable grasses for space, light, nutrients and moisture, limiting the success of reseeding and pasture establishment (Mganga et al, 2021), consequently affecting livestock production. Some weeds in hay pastures can be poisonous (Ekwealor et al, 2019), necessitating the need for eradication before they are mowed together for baling. Smelly weeds in harvested hay may limit the intake of feed in livestock compromising productivity.…”

Weed control and weed biomass influenced first cutting forage accumulation and nutritive value of spring‐seeded alfalfa

“…While arguments like this are important for sustainable weed management, no thresholds have been established for weed biomass or compositions that optimize forage accumulation without reducing forage nutritive value. In addition, weeds from certain genera, such as Amaranthus , Chenopodium , Solanum , and so forth, may accumulate compounds such as nitrates, which may be toxic to livestock if the nitrate levels exceed certain thresholds (Bolan & Kemp, 2003; Ekwealor et al., 2019). The objectives of this study were to (1) evaluate the effect of weed control treatments on alfalfa forage accumulation, weed biomass, and nutritive value of the first cutting of spring‐planted alfalfa and (2) assess the relationship between the proportion of individual weed species biomass on nutritive value components and nitrate accumulation of the forage mixture.…”