They are the most used pesticides and are essential components of many agricultural systems. However, some herbicides can kill all vegetation that they come in contact with, including the crop. Usually, the list of susceptible plants is printed on the herbicide label, which is a legal binding document . There is little if any residue left in the soil. Main symptoms of contact herbicides are rapid kill of the target plants, and foliar chlorosis followed by necrosis within hours after application.
Contact herbicides are most effective against annual weeds.
Often, symptoms are not immediate and take time to develop. Systemics are effective against all types of weeds, but most importantly against perennials. Crop injury - injury sustained by a nontarget vegetation or crops in which a herbicide was registered for use. Mode of action is the physiological and biochemical processes by which herbicide brings injury or death to the susceptible plant. Thirteen herbicides are going to be evaluated for this lab.