Herbicides plant-growth substances

D from MeOH. It is a plant growth substance, a herbicide and is TOXIC. [Beilstein 6IV 908.]... 

Auxins. Term for naturally occurring or synthetic plant growth substances which resemble the natural plant hormone auxin ( 3-indolylacetic acid) in their activities. In low doses A. have growth stimulating activities and at higher doses herbicidal effects. 

Pesticides are chemicals or biological substances used to kill or control pests. They fall into three major classes insecticides, fungicides, and herbicides. Others classes are rodenticides, nematicides, molluscicides, and acaricides. These chemicals can be natural compounds or synthetic ones. Pesticides may also be divided into contact and systemic pesticides. Pesticides that were earlier produced were of the contact type. They do not appreciably penetrate plant tissue, so they are susceptible to the effects of the weather and moreover new plant growth is not protected. Vice versa, most of the recently developed pesticides are systemically active. They move through the plant vascular system and thus they not only can protect a plant from attack but also inhibit or cure established infections. Systemic pesticides are not affected by weathering and also confer immunity to all new plant growth. In 1993, 57% of all the pesticides used in the United States were herbicides, while 23% and 12% were insecticides and fungicides, respectively [1]. 

Senesi N, Loffredo E (1994) Influence of soil humic substances and herbicides on the growth of pea (Pisum sativum L.) in nutrient solution. J Plant Nutr 17 493-500... 

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