Weeds control invasive

With the first invasion of resistant weed populations, prompt action has been essential to avoid serious and permanent problems. Preventive action to avoid herbicide resistant weeds from evolving in the first place is definitely the best strategy. It is virtually essential in all cases of herbicide resistance to have other classes or types of herbicides, with alternate sites, modes of action and degradation available. In some countries, because of failure to respond promptly, the lack of suitable alternatives, or for other reasons, triazine resistant weeds have not been controlled, resulting in rapid spread,.leading to the almost total loss of effective weed control with these herbicides (1). 

Control of broadleaf weeds with 2,4-D has posed a new problem, the invasion of fields by true grasses, which will need specific herbicides. 

The water hyacinth Eichhornia crassipes originates from Brazil, and although it represents one of the most troublesome and invasive of water weeds, it is also one of the best phytoremediants of polluted water. The biomass becomes saturated with pollutants, which can then be removed from the water by harvest of the biomass and its composting, a process which achieves a substantial reduction in the mass requiring further processing (e.g., incineration under controlled conditions). The species is highly susceptible to frost, but in frost-free environments, its introduction is risky as it can readily become uncontrollable. 

Other workers have examined the use of insects to consume troublesome weeds. Again there are problems associated with the selection of an insect that is specific to the weed and has no other disadvantages such as the sensitivity of some people. Such systems are unlikely to become widely used in agriculture but do find small niche markets, especially with the home gardener. Workers in South Africa have evaluated several insects for the control of the invasive weed Lantana camara and the aquatic fern Salvinia molesta with encouraging results.9 The grass carp has also been recommended for control of a number of submerged aquatic weeds. 

One exception, however, is the kudzu vine (Puer-aria lobata), native to Japan and introduced to the southeastern United States as a forage plant and for use in controlling erosion. This species is considered to be a serious, invasive weed in some places. Control methods for the kudzu include the use of herbicides and the excavation of its large, underground, roots. 

Herbicides are applied to roadways and railroad rights-of-way to control weeds and other plant life for safety and fire prevention purposes. Though arsenic herbicides were used for more than half of the twentieth century, these have been largely replaced by 2,4-D, triclopyr, and picloram. These herbicides have been found in wells adjacent to the application points. Pesticides and herbicides are also applied directly to surface water for the control of insects, algae, and invasive weeds. 2,4-D, glyphosate, and copper sulfate are the pesticides most commonly applied to surface water)... 

Control of insect pests and invasive weeds has become very sophisticated. Knowledge of the interaction between insects and host plants is critical to development of effective control strategies diat are friendly to the environment. We must also understand how insects communicate with each other. What are the semiochemicals (signal substances such as sex pheromones) and how do they function Research efforts in this fast-growing field involve organic chemists, analytical chemists, entomologists, biochemists, microbiologists, formulation experts, and statisticians. 

Steps in accomplishing the goal of utilizing pheromone semiochemicals from insects to control pests and invasive weeds include 1) establishing laboratory cultures of the insect species having economic impact on agriculture... 

Pesticides and herbicides are also applied directly to surface water for the control of insects, algae, and invasive weeds. 2,4-D, glyphosate, and copper sulfate are the pesticides most commonly appfied to surface water [9]. 

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