Comparison of three herbicides and combinations for weed management in citrus

Ben Faber,Jose De Soto,Oleg Daugovish,Travis Bean,Anna Howell

doi:10.4322/crt.icc129

Abstract

At a clay loam site near Santa Paula, California, was examined the weed control efficacy of two products with the active ingredient indaziflam, applied at two rates (Alion 200 SC at 365 ml ha-1 and Alion 500 SC at 146 ml ha-1). These were applied alone and in combination with rimsulfuron (Matrix) at 146 ml ha-1, which was also applied alone at 292 ml ha-1, for a total of five herbicide treatments plus an untreated control for fall and spring application timings (November 2015 and February 2016, respectively). Treatments were applied to clean row middles that had been previously treated with glyphosate and shallow cultivation. Weed control was evaluated at two, four, and six months after treatment. The most common weeds in the plots were species of Malva, Conyza, Convolvulus, Euphorbia and Chenopodium. For all species combined, both indaziflam products plus rimsulfuron, Alion 200 SC alone, and Matrix alone had lower weed densities than untreated control regardless of time since treatment.

Highlights

Weeds can impact cultural operations, tree growth, and yields by altering the spray pattern of low-volume irrigation systems, intercepting soil-applied chemicals, reducing grove temperatures during freeze events, and interfering with pruning and harvest operations
Herbicides used in a citrus grove are generally divided into two groups: 1) soil-applied herbicides that should be applied to fairly clean soil surfaces prior to weed emergence, and 2) foliar-applied herbicides that are applied after weeds have emerged (Futch et al, 2016)
Treatments were applied to 6 m × 7 m plots with CO2-pressurized backpack sprayer at spray volume 470 l ha-1 to clean row middles that had been previously treated with glyphosate and shallow cultivation one month prior to trial treatments

Summary

Introduction

Weeds can impact cultural operations, tree growth, and yields by altering the spray pattern of low-volume irrigation systems, intercepting soil-applied chemicals (fertilizer and agricultural chemicals), reducing grove temperatures during freeze events, and interfering with pruning and harvest operations. Weeds growing around tree trunks may create a favorable environment for pathogens that infect the trunk and roots (Futch et al, 2016). Weed species compete with citrus trees in many ways and with varying intensities; management of more competitive weeds such as Conyza bonariensis (L.) Cronq. While some weeds (e.g., Tribulus terrestris L., Xanthium strumarium L., Urtica urens L., Cirsium vulgare (Savi) Ten., and Picris echioides L.) may have low competitive effects on citrus trees, they can hinder labor operations and may rank high for active management. Herbicides used in a citrus grove are generally divided into two groups: 1) soil-applied herbicides (pre-emergence) that should be applied to fairly clean soil surfaces prior to weed emergence, and 2) foliar-applied herbicides (post-emergence) that are applied after weeds have emerged (Futch et al, 2016)

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Conclusion