Postemergentteja

Postemergentteja, or postemergent herbicides, are chemical tools applied after the crop and weeds have emerged to control actively growing weeds. They contrast with preemergent products that are applied before emergence to form a soil barrier. Postemergents can be selective, harming some species but not the crop, or nonselective, killing all vegetation they contact.

They may be systemic, absorbed and translocated to growing points, or contact, causing rapid tissue damage. Timing is crucial: applications are made after weed emergence and when weeds are susceptible, typically before crop stress or unfavorable environmental conditions.

Representative classes include auxin-mimics such as 2,4-D and dicamba, which disrupt growth regulation in broadleaf weeds; EPSP synthase inhibitors like glyphosate, which provide broad nonselective control; and other modes of action used in specific cropping systems. Some postemergents are crop-tolerant, enabling selective weed control in sensitive crops.

Use of postemergentteja requires consideration of resistance management, rotation of modes of action, and integration with cultural practices. Potential risks include non-target injury through drift, volatilization, or misapplication, and environmental concerns such as effects on non-target plants and aquatic ecosystems.

Regulatory status and approved uses vary by region; product labels provide guidance on crops, timing, rates, and tank mixes. They are commonly included in integrated weed management programs to tailor control to local weed flora and crop systems.