Crop residue and rainfall timing effect on pre-emergence herbicides efficacy using different spray nozzle types

Abstract

Weed control success with pre-emergence (PRE) herbicides is affected by environmental factors including rainfall and plant residue. Two greenhouse experiments were conducted to evaluate PRE herbicide efficacy against johnsongrass [Sorghum halepense (L.) Pers.], prickly sida (Sida spinosa L.) and velvetleaf (Abutilon theophrasti Medik.). One experiment investigated herbicide efficacy under two crop residue amounts (2500 and 5000 kg ha⁻¹) and the second examined herbicide efficacy influenced by simulated rain at two, four, and eight days after application (DAA). Five herbicides (pendimethalin, metribuzin, clomazone, imazethapyr and pyroxasulfone) and four nozzles types (XR, ULD, TTI and TTI60) were used. Nozzle type did not affect weed control across residue levels. Pendimethalin better controlled S. halepense under the low residue level. Imazethapyr efficacy for S. spinosa and A. theophrasti increased under high residue level. Imazethapyr applications for S. spinosa and A. theophrasti control were more effective when sprayed with the TTI nozzle regardless of rainfall timing. Longer periods without rain after application improved pendimethalin efficacy against S. spinosa and A. theophrasti, while pyroxasulfone better controlled S. spinosa with rain two DAA. Metribuzin and clomazone provided the best weed control among herbicides for all residue levels and rainfall scenarios.

Keywords:

• Droplet size
• weed control
• weeds
• herbicides
• soil

Disclosure statement

We do not have no conflict of interest.

Funding

This work was supported by the United States Department of Agriculture (USDA) Hatch Project Funding “MIS-522070” but was not supported with industry funding.

Data availability statement

The data that support the findings of this study are available from the corresponding author, PHUF, upon reasonable request.