Integrated pest management procedures are vital to accomplishing environmentally sound pest management.It is important to recognize all the parts of integrated weed management when employing any weed control program.These integrated approaches include mechanical, cultural,physical,chemical,and biological methods. Herbicides have been an important tool for management of weeds in urban and rural environments for many years.Since the 1940 ’s, herbicides have become more sophisticated with regard to what weeds they control,length of control,and how they might affect desirable vegetation.Although the use of herbicides is widely accepted and practiced,it is probably the least understood segment of an integrated weed management program.There are many publications available that describe how herbicides work and their mechanism of selectivity. Classification of herbicides by mode-of-action gives us an in-depth appreciation of how the herbicide affects susceptible plants from the time it is absorbed until plant death.Knowledge of herbicide mode-of-action helps us to understand the relationship that some herbicides have to others with regard to activity and selectivity.It also helps us to recognize what type of noticeable effects herbicides will have on plants either at lethal or sublethal doses. Although there are many ways to classify herbicides,using and understanding herbicide mode-of-action can help diagnose injury problems.Mode-of-action groups include growth regulators,photosynthetic inhibitors,pigment inhibitors,seedling growth inhibitors,cell membrane disrupters, lipid synthesis inhibitors,and amino acid synthesis inhibitors. It must be understood that other symptoms caused by insects,diseases,and abiotic stresses can mimic the effects of some herbicides.Therefore,diagnosis of herbicide injury should include a careful consideration of other biotic and abiotic possibilities.The following information describes some of the common herbicide injury problems to cotton.Remember to always carefully read and follow label instructions for safe and effective use of herbicides.

Dinitroanilines (Treflan ®,Prowl ®)
These herbicides interrupt mitosis (cell division), which stops root growth.Susceptible plants will die due to their limited ability to take up sufficient water and nutrients to sustain growth. Cotton root growth and development will be severely limited in the herbicide zone,and roots in the herbicide zone will be stubby and thick, especially the first-order laterals.Normal roots can be found above and below the treated zone. Callus tissue (tumors)may form on the stem at the soil surface if these herbicides are not properly incorporated.This may result in lodging due to the stem breaking.Affected plants will appear dark green and may be stunted.

Chloroacetamides (Dual ®)
These herbicides act on germinating seeds.They disrupt protein synthesis,which slows cell division and enlargement.Injury may be observed as root growth inhibition,although most of the symptomology will be improper leaf unfurling,leaf cupping,crinkling,and overall plant stunting.Some plants will produce leaves that do not emerge above the soil surface.

Phenoxy Acetic Acids (2,4-D)
These herbicides upset the normal hormonal balance that regulates plant processes such as cell division,cell elongation,protein synthesis and respiration.It is easy to see aerial drift characteristics,as the leaves will appear strapped.However,it is more difficult to see slight injury initiated from soil uptake.Cotton roots will be twisted (epinasty),swollen and appear disoriented.Roots that penetrate into a herbicide area from a spot treatment will cease growing and the root tip will swell and turn necrotic.Callus growth may appear on roots as well as stems.

Benzoic Acid (Clarity ®)
This is similar to the phenoxy acetic acids above. Leaves will be cupped more than strapped.The root characteristics are similar to the phenoxy acetic acids.

Carboxylic Acid (Tordon ®,Paramount ®)
This is also similar to the phenoxy acetic acid damage described above.In general,these herbicides are considered more herbicidally active pound-for-pound compared to the benzoic and phenoxyacetic acids.

Prowl ®


Dual ®


Dual ®


Normally Developed Root