Plants growing on the orchard floor become weeds when they compete with citrus trees for water, nutrients, and light contribute to pest problem, interfere with cultural operations, or increase frost hazard. Competition may vary with weed species and density but is particularly strong in newly planted orchard; stressed young trees grow slower and may become less tolerant of damage from insects and diseases. Weeds around tree trunks may create a favorable environment for pathogens that infect the trunk and roots. As the trees grow older, the tree skirts and canopies shade part of the orchard floor and reduce weed growth....