Terbufos residues in wheat and barley

Area of Science:

• Agricultural Science
• Environmental Chemistry
• Pesticide Science

Background:

• Terbufos is an organophosphate insecticide used for soil pest control.
• Understanding pesticide residue levels in crops is crucial for food safety and environmental assessment.

Purpose of the Study:

• To quantify terbufos residues in wheat and barley following in-furrow application.
• To determine the dissipation rate of terbufos residues in crop foliage and grain.

Main Methods:

• Granular terbufos (Counter 15G) applied at 1.5 and 3.0 kg/ha during planting.
• Foliage, grain, and straw samples analyzed for total terbufos residues (as terbufoxon sulfone) at various time points.
• Residue analysis conducted on wheat and barley crops.

Main Results:

• Maximum wheat foliage residues were 7.4 and 10.6 ppm at 10 days post-seeding for the lower and higher application rates, respectively.
• Residues in wheat foliage decreased to 0.32-0.58 ppm by 53 days post-seeding.
• Barley foliage showed lower residues than wheat, with maximums of 4.4-7.0 ppm at 10 days and 0.21-0.34 ppm at 53 days.
• Grain samples contained 0.01 ppm or less terbufos residues at harvest.
• Straw samples had up to 0.75 ppm total terbufos residues at harvest.

Conclusions:

• Terbufos application resulted in transient residues in crop foliage.
• Minimal terbufos residues were detected in harvested grain, suggesting low potential for dietary exposure.
• Further monitoring may be warranted depending on crop type and application rates.