A century of progress in weed control in hardwood seedbeds
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Weeds have existed in nurseries since before the time Bartram grew hardwoods during the 18th century. Hand weeding was the primary method of weed control during the first part of the 20th century. From 1931 to 1970, advances in chemistry increased the use of herbicides, and advances in engineering increased the reliance on machines for cultivation. Many managers now rely on chemical treatments, including methyl bromide, chloropicrin, and various selective herbicides. The last 3 decades of the 20th century saw an increase in regulation of chemicals due to health and environmental concerns. If soil fumigation becomes impractical due to governmental regulation, hand-weeding times in hardwood seedbeds will likely increase unless managers adapt to the change. Some managers will increase their use of sanitation practices and herbicides. Although a few herbicides are registered for use on hardwoods, many herbicides that may be used on food crops cannot be legally applied to hardwood seedbeds. In general, grasses can be effectively controlled with properly timed, selective herbicides. The germination of many small-seeded broadleaf weeds can be suppressed with preemergence herbicides. Several perennial weeds and various broadleaf weeds, however, are difficult to control with pre-emergence herbicides. For some difficult-to-control weeds, a few nursery managers use shielded herbicide sprayers to apply non-selective herbicides between drills.