AGRICULTURE

1. History
(herbecide)
2,4-D, was first discovered and synthesized
by W. G. Templeman at Imperial Chemical
Industries. In 1940, he showed that
"Growth substances applied appropriately
would kill certain broad-leaved weeds in
cereals without harming the crops." By
1941, his team succeeded in synthesizing
the chemical. In the same year, Pokorny in
the US achieved this as well.[3]

2. Further discoveries
• The triazine family of herbicides, which includes atrazine, were
introduced in the 1950s; they have the current distinction of being
the herbicide family of greatest concern regarding groundwater
contamination. Atrazine does not break down readily (within a few
weeks) after being applied to soils of above neutral pH. Under
alkaline soil conditions, atrazine may be carried into the soil profile
as far as the water table by soil water following rainfall causing the
aforementioned contamination. Atrazine is thus said to have
"carryover", a generally undesirable property for herbicides.
• Glyphosate (Roundup) was introduced in 1974 for nonselective
weed control. Following the development of glyphosate-resistant
crop plants, it is now used very extensively for selective weed
control in growing crops. The pairing of the herbicide with the
resistant seed contributed to the consolidation of the seed and
chemistry industry in the late 1990s

3. Glyphosate
• a systemic nonselective herbicide, is used
in no-till burndown and for weed control
in crops genetically modified to resist its
effects

4. Weed
• is a plant considered undesirable in a
particular situation, "a plant in the wrong
place". Examples commonly are plants
unwanted in human-controlled settings, such
as farm fields, gardens, lawns, and p"weed"
has no botanical significance, because a plant
that is a weed in one context is not a weed
when growing in a situation where it is in fact
wanted, and where one species of plant is a
valuable crop plant,