Control Of Weeds As A Plant, By Jethro Tull

Jethro Tull first coined the term “weed” in 1931 in the book “Horse Hoeing Husbandry”. A weed is a plant growing in a place where it is not desired (Buchholtz, 1967; Klingman and Noordhoff, 1961; Patil et al., 2010). The plants growing in agricultural fields having more negative values and competing with the main crops for soil, water, nutrients etc. are known as weeds (Ali et al., 2003; Muzik, 1970). Zimmerman (1976) believes that the term “weed” should be used to describe plants that have all the following characteristics: (1) they colonize disturbed habitats, (2) they are not members of the original plant community, (3) they are locally abundant and (4) they are economically of little value.
In the world there are 30,000 weed species, out
Mechanical control includes mowing, hoeing, and hand pulling. Chemical control involves the use of herbicides. Biological weed control is an approach using living organisms to control or reduce the population. The objective of weed biological control is not the eradication of weeds but the reduction and establishment of a weed population to a level below the economic threshold. Biological control (biocontrol) of weeds has a long history and a good success rate. Biological control of weeds is the intentional use of living organisms (biotic agents) to reduce the vigour, reproductive capacity, density, or the impact of weeds. Bioherbicides comprising microbial agents such as obligate fungal parasites, soil-borne fungal pathogens, non-phytopathogenic fungi, pathogenic and non-pathogenic bacteria and nematodes. Several selected microorganisms have been extensively evaluated and developed or are under development for commercial
There are several methods of weed control, which include 1) Cultural and mechanical weed control methods, 2) Chemical weed control methods, 3) Biological weed control methods (Tu et al., 2001). Commonly used weed control strategies such as hand weeding, mechanical weeding and chemical herbicides can control certain weed species. However, hand weeding is time-consuming and very expensive, while the use of chemical herbicides, on the other hand, not only are becoming more expensive, but also contribute to environmental pollution. Weeding, usually by hand, accounts for up to 60% of total pre-harvest labour input in the developing world (Webb and Conroy, 1995). The management of weeds is a necessary but expensive challenge, and chemical weed control accounts for over $14 billion spent annually on herbicides (Kiely et al., 2004). Weeds are the most important of the economic and environmental pest problems, and they are the target of much of the chemicals applied throughout the world. Thus, herbicides comprise 47% of the world agrochemical sales, and insecticides 29% and most of the rest being fungicides (Woodburn,