ORIGINAL ABSTRACT

Eucalyptus stands out as one of the most productive tree species for large-scale cultivation. However, like all cultivated crops, it requires specialized management practices, including the control of weeds, pathogens, and pests. Glyphosate is the most widely applied herbicide used in the essential weeding effort, and it ensures the sustainable management of eucalyptus cultivation in Brazil. Given the sensitivity of eucalyptus to glyphosate, existing weed control methods in young eucalyptus farms predominantly rely on protected mechanical or/and knapsack spraying. Both methods contribute to herbicide drift, which compromises tree yield and increases chemical waste due to uneven spraying. This study provides a detailed observation of the physiological parameters and long-term field performance of glyphosate-tolerant (HT), genetically modified (GM) eucalyptus developed by FuturaGene/Suzano S.A. and approved in Brazil for operational deployment. The HT GM eucalyptus events were meticulously evaluated to ensure high levels of glyphosate tolerance. This involved the direct application of herbicide on seedlings in greenhouse studies and on young trees in field conditions. The herbicide-treated GM eucalyptus in all trials demonstrated consistent growth and maintained physiological parameters comparable to their respective non-sprayed wild-type (WT) counterparts. The HT GM eucalyptus represents a significant advancement by enabling the direct application of glyphosate over the top of the trees to control the weeds within the planting row. This innovative approach minimizes the need for frequent mechanical and manual interventions, thereby lowering worker herbicide exposure, reducing the environmental impact of mechanical operations, and enhancing the overall efficiency and sustainability of HT GM eucalyptus stands.