Selectivity of the Herbicide Chlorimuron Ethyl on Young Coffee Plants

Abstract

The great interference of weeds in coffee plants, due to competition for water, light and nutrients, makes their control essential. Among these control methods, the chemical stands out, due to its high efficiency and low cost. However, as a function of application failures, phytotoxicity is frequent in coffee plants due to herbicide drift. Aiming to search for active ingredients selective to coffee, the objective of this study was to evaluate the selectivity of the active ingredient Chlorimuron ethyl in coffee seedlings, and its effects on plant morphology, anatomy and physiology. The experiment was carried out in a greenhouse with ‘Topázio MG 1190’ coffee plants (<em>Coffea arabica</em> L.), grown in 11-L pots. The statistical design was in randomized blocks, with four replications and four herbicide doses. Each plot consisted of three plants. The treatments were: 0%; 50%; 100% and 200% of the recommended commercial dose of the herbicide Chlorimuron ethyl. Evaluations were performed at 120 days after treatment application. Morphological, physiological and anatomical characteristics were evaluated, besides possible phytotoxicity symptoms inherent to herbicide application. The herbicide Chlorimuron ethyl caused phytotoxicity symptoms in coffee seedlings, evidenced from the leaflet dose, through leaf deformation and cracking, with growth losses not exceeding 10%, but without damage to plant physiology and anatomy.

Phytotoxicity and leaf anatomy of young coffee plants subjected to herbicides exclusively and in associations

“…As well as the symptoms of phytotoxicity, the time factor is also crucial for observing changes in anatomical leaf characteristics in coffee plants submitted to herbicide application. In this work, changes in anatomical leaf characteristics were identified at 65 DAA, despite that, Voltolini et al (2019) and Castanheira et al (2019a) did not find influence of these characteristics at 120 DAA of the herbicides fluazifop-p-butyl and chlorimuron-ethyl respectively.…”

“…One of the main mechanisms that confer the natural tolerance of some plant species to ALS-inhibiting herbicides is metabolism at the non-target site (Yu;Powles, 2014), which explains the deformity of the leaves of coffee trees when treated with this group of herbicides, showing that phytotoxic effects occur at the application site. Castanheira et al (2019a) reported deformations and fissures in the leaves of coffee seedlings 120 days after the application of chlorimuron-ethyl. In the same way, Ronchi and Silva (2003) observed mild symptoms that appeared late in newly planted coffee trees after simulated drift of this herbicide.…”

“…Even though it can translocate, the rapid contact action of saflufenacil, causing the death of cells (Dalazen et al, 2015;Grossmann et al, 2010), prevented its effect on the coffee tree's paradermic and vascular bundle characteristics. The results of ALS and ACCase-inhibitorscan be explained by the crop tolerance mechanism, where their potential for damage is minimized (Castanheira et al, 2019a;Yu;Powles, 2014).…”

“…Acetyl-CoA carboxylase (ACCase) inhibiting herbicides appear as an alternative to glyphosate, which is a non-selective full-action herbicide for coffee trees, as well as the possibility of association with ALS-inhibiting herbicides. In this context, Castanheira et al (2019a) and Voltolini et al (2019) observed that the herbicides chlorimuronethyl (ALS) and fluazifop-p-butyl (ACCase) did not cause significant changes in growth and physiological characteristics and morphological characteristics of coffee seedlings even submitted to high doses of these herbicides.…”