Response of some monocotyledonous and broadleaf weeds to flaming

Abstract

This study aimed to evaluate the response of various weed species to single flaming treatments at different Liquefied Petroleum Gas (LPG) doses and growth stages by analyzing dry matter content in the above-ground foliage of weeds and making visual observations on weed control rates. A two-year field experiment was conducted using a weed flamer on a bare plot. Five distinct LPG doses (30, 45, 60, 75, and 90 kg ha-1) were applied at varying operating pressures and ground speeds with a range of 1.5-2.5 bar and 3.9-7.2 km h-1, respectively. Data were analyzed using log-logistic statistical models to assess the effects of flaming treatments on weed stem length and dry matter. For all tested weed species, an LPG dose of 60 kg ha-1 reduced the above-ground foliage weight by approximately 50% compared to untreated control plants at 14 days after treatment (DAT14). The rate of dry matter control increased significantly when the LPG dose was raised from 45-60 kg ha-1, mirroring the trend observed for stem length reduction. However, doses above 60 kg ha-1 applied at the 2-4 leaf (L) growth stage did not substantially improve the control rate. In contrast, for certain weed species at the 10-12 L stage, the response curve plateaued or even declined beyond a LPG rate of 90 kg ha-1. The findings indicate that achieving the desired physical control of weeds requires high LPG doses, which could escalate application costs. Based on current market prices in Turkey, flaming may be more cost-effective than herbicide use only when an 80% weed control rate is targeted for broadleaf weeds at the 2-4 L growth stage with LPG doses ranging from 60-75 kg ha-1. For other growth stages of broadleaf weeds and all stages of monocotyledonous weeds, herbicide application costs remain lower than those of flaming.