Pesticides and Pest Control

This question is essentially identical to 228906. Weedicides are sprayed during the vegetative growth of weeds before flowering occurs. This prevents seed production and breaks the weed life cycle. The timing is critical - applying weedicides after flowering allows seeds to mature and disperse, reducing effectiveness.

 Pyrethrin is a safe insecticide of plant origin.

Citronella oil is an insect repellant.

The larvae of the darkling beetle and the rhinoceros beetle are commonly eaten. Thus, it is economically important as food.

The chemical substances which are used to kill the insects are called insecticides. For example: DDT

Mycotoxin is a toxic secondary metabolite produced by organisms of fungi.

Statement 1 is wrong because alachlor is a herbicide used to control the growth of broadleaf weeds and grasses in corn and many other crops. Statement 2 is correct because it mixes well with other herbicides. It is used mainly to control annual grasses and broadleaf weeds in corn (maize), soybeans and peanuts. Statement 3 is correct. Alachlor is slightly toxic because, when it is exposed to levels above the maximum contaminant level (MCL), there occurs slight skin and eye irritation and at lifetime exposure to levels above the MCL, it causes potential damage to liver, kidney, spleen, lining of nose and eyelids.

The advantages of using biopesticides:

Agrobacterium radiobacter is an effective, commercially applied, biological control agent for the prevention of crown gall disease caused by many virulent strains of Agrobacterium tumefaciens and Agrobacterium rhizogenes. Trichoderma harzianum is an effective biocontrol agent against several fungal soil borne plant pathogens.

DDT (Dichlorodiphenyltrichloroethane) is a synthetic organochlorine insecticide used to control mosquitoes and agricultural pests. It is not a herbicide (kills weeds), fungicide (kills fungi), or rodenticide (kills rodents).

Pesticides are chemical substances primarily used to destroy or control insects that damage crops. While they can affect other organisms, their primary agricultural use is insect pest management. The word is derived from 'pest' - mainly insects that harm agricultural produce. Herbicides (for weeds) and fungicides (for fungi) are different categories.

DDT (Dichlorodiphenyltrichloroethane) is a synthetic insecticide that was widely used to control mosquitoes and other disease-carrying insects. It works by disrupting sodium ion transport in nerve cells, leading to paralysis and death. Herbicides kill weeds, fungicides kill fungi, and rodenticides kill rodents. DDT's use is now restricted due to environmental concerns.

Freon (chlorofluorocarbons) is not a pesticide; it is a refrigerant and propellant that was phased out due to ozone layer damage. BHC (benzene hexachloride), Malathion, and DDT are all organochlorine or organophosphate pesticides used in agriculture and public health.

Seeds are treated with fungicides to avoid seed-borne diseases. So, this is the correct answer.

Weedicides are used to kill weeds.