The Christmas tree industry is a million-dollar industry in the United States. Like all crop production systems, Christmas trees are also affected by weeds. Noxious plants such as Canada thistle, horsenettle, poison ivy, and pokeweed compete with Christmas trees not only for light, space, moisture, and nutrients but also harbors pests and pathogens. Additionally, they attract wild animals like deer which are detrimental to this tree production. Large weed species create significant difficulty in crop management practices and intercultural operations. Christmas trees are more prone to damage from weeds in the seedling beds and the first three years in the field after transplantation. Young trees often suffer moisture stress due to weeds and succumb to drought. Once established, weeds are very difficult to manage, particularly the management of vining and woody weeds without damaging the Christmas trees is almost impossible. In severe cases, they devastate the whole production system and cause unbearable losses to growers. The most commonly used method for weed management in Christmas tree production is the application of chemical herbicides. Herbicides can cause severe injury to Christmas trees if applied inappropriately and can cause environmental issues. In addition, repeated use of the same herbicides can trigger herbicide resistance in weed species. Chemical mowing is a weed control technique that has been implemented in Florida citrus production, and it has been successful. Chemical mowing consists of the use of sublethal rates of postemergence herbicides in conjunction with mechanical mowing. However, there is no data or research showing whether this can be implemented in the flat land Christmas tree production system. How can chemical mowing help prevent weed shifts and herbicide resistance from developing? These significant knowledge gaps have led to the development of this master’s research proposal. Hence the objectives of this research proposal are: Developing a chemical mowing strategy in Christmas tree production by evaluating the efficacies of three different postemergence herbicides at lower rates combined with mechanical mowing; Evaluating their phytotoxic effects on two different varieties of Christmas trees; Determining the optimal moisture range for efficient chemical mowing. The preliminary results showed that an effective weed control can be achieved in Christmas tree production at sublethal rates of postemergence herbicides. Also, no significant injury was observed in Christmas trees due to chemical mowing.
