Using Herbicides to Manage Noxious Weeds
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Transcript Using Herbicides to Manage Noxious Weeds
Exploring Herbicides Used
to Control Invasive Weeds
Herbicide History
Chemical Weed Control
Chemical weed control
• Advanced human ability to manipulate
environment to our advantage
Herbicide development
• Stimulus:
realized chemical environment of plant easier to
manipulate than climatic, edaphic, or biotic
environments in which they grow
Herbicide Development
Herbicides used to:
• Reduce or eliminate labor and machine
requirement for ag production
• Modify existing crop production techniques
• Improve farm efficiency
• Reduce horse power and other energy
inputs
Capacity to do work
Obviously remembering herbicides are derived
from petroleum
Chemical Control History
Three ages of agriculture
• Blood, sweat, tears period
Fatigue, famine
• Mechanical age
1701 Jethro Tull; seed drill; horse hoe
1791 Eli Whitney; cotton gin
1834 Cyrus McCormick; Obed Hussey; reaper
1837 John Deere; steel plow
• Chemical age
Chemical Control History
1200 BC armies salt & ash fields
1000 BC Homer wrote about sulfur &
pest control
470 BC Democritus, clear forests
w/hemlock juice in which lupine flowers
soaked
400 BC Theophrastus, trees killed by
pouring oil over their roots
Chemical Control History
146 BC Romans sack Carthage & salt
crop fields
1st Century BC Cato, amurca (watery
residue after oil drained from olives)
for weed control
1594 salt used for selective & nonselective weed control
1676 soot used for moss control
1785 soap boiler’s ashes for weed
control
Chemical Control History
70 AD, 1759 ferrous sulfate known to
be phytotoxic
1804, 1821 copper sulfate shown to be
phytotoxic
1896 copper sulfate used to selectively
control mustards in cereals
1854 salt (NaCl) first recommended in
Germany
Chemical Control History
1855 sulfuric acid used in Germany in
cereals & onions
1865 Bordeaux mixture France in grapes
for downy mildew; blackens yellow
charlock
1902 sodium arsenite used by Army
Corps Engineers for water hyacinth, LA
Chemical Control History
1906 carbon bisulfide soil fumigant for
thistle and bindweed
1914 petroleum oils used
1923 sodium chlorate first used France
for bindweed
1930 sulfuric acid used in England
1932 introduction of first organic
chemical weed control; DNOC
Chemical Control History
1940 ammonium sulfamate for brush
control
1941 Porkony synthesizes 2,4-D
1942 2,4-D growth regulator, not yet
reported herbicidal
1944 2,4-D herbicidal properties
recognized
1945 MCPA first tested as herbicide
Chemical Control History
1946 first reported use 2,4-D for dandelion
control in turf
1951 monuron effective grass control
1958 atrazine & paraquat introduced
1960 trifluralin available
1960s pyridines introduced
1971 glyphosate introduced
Late 70s sulfonylureas introduced
1980s imidazolinones introduced
2003 pyrimidines introduced
Chemical Control Advantages
Economic
• Primarily due to decreased farm labor
Apply in crop rows where cultivation
impossible
• Also decrease tillage and subsequent injury
Preemergence treatments early season
weed control
Chemical Control Advantages
Decrease tillage soil destructive
effects
• Alterations to soil structure
Better perennial weed control
• Poorly control by hand labor
Decrease fertilizer, harvest, seed
conditioning costs
Chemical Control Disadvantages
Cost
• Although least expensive portion of weed
management
Toxicity
Environmental contamination
Restrict crop rotation
Non-target plant hazard
Weed shifts
Chemical Control Disadvantages
Encourages monocultures
Soil erosion – bare ground treatments
Over dependence
• Tendency to make up for other poor mgmt
practices
Application expertise & precision needed
Pest resistance
Inconsistent environmental interactions
Waste disposal