Impact of site-specific management on Sorghum halepense control and maize yield

Abstract

Sorghum halepense (Johnsongrass) is a weed that tends to spatially distribute in an aggregated manner in maize crops. In a two-year study conducted at La Poveda (CSIC, Madrid), the effectiveness of Precision Agriculture (PA) in controlling this weed was investigated by: 1) monitoring the spatio-temporal dynamics of Johnsongrass patches in a maize field using UAV aerial image processing; 2) site-specific application of the herbicide nicosulfuron according to the early-stage map generated from aerial imagery; and 3) quantification of crop yield in Johnsongrass treated and untreated areas, as well as weed-free. The analysis of the map prior to herbicide treatment in 2022 revealed a random distribution of Johnsongrass, with patches averaging 0.4 m² in size, ranging from 0.01 m² to 5 m². Site-specifically treated plots showed spatial growth control, evidenced in the subsequent season (2023) with an average patch size of 1.0 m², ranging from 0.02 m² to 12 m². In contrast, untreated patches significantly increased in size (average 3.8 m²; ranging between 0.01 m² and 122 m²). There was a notable decrease in yield in untreated infested areas compared to treated and/or Johnsongrass-free areas. These findings underscore the advantages of PA in Johnsongrass control, demonstrating how detection and site-specific patch management can reduce herbicide use by up to 95% and mitigate competition with the maize crop.