Introduction to Non-Selective Herbicides
NSH’s are used under different patterns according to the crop:
In plantation crops (rubber, oil palm, orchards, vines) they are applied on weeds growing between the trees for several purposes: to facilitate passage in tropical crops, to save moisture in vines and orchards, to reduce or erosion associated with cultivation. Typically these herbicides can be applied without damage to the bark of trees but not to the leaves.
In annual crops in several modes:
Preplanting to eliminate weeds prior to planting. The objective is also to reduce cultivation
Early post planting prior to emergence
Post planting, interow spraying with spray guards to protect the crops
Preharvest to desiccate weeds and crops
Post harvest to reduce perennial weeds
NSH’s mostly belong to two groups according to their properties:
Contact herbicides (and or desiccants) only affect the area sprayed, they are usually fast acting and rainfast. They work well on annual species and are adapted to quickly remove the vegetation prior to especially in tropical environment. Glyphosate is a good example of this class. Systemic herbicides: the product moves within the plant from the point of contact, typically towards the growing points the will be destroyed. They are well adapted to controlling perennial species that have strong root systems.
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