Organic Weed Control in Perennial Navajo Tea Greenthread

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2009: $15,000.00
Projected End Date: 12/31/2010
Region: Western
State: New Mexico
Principal Investigator:


  • Additional Plants: herbs


  • Pest Management: flame, integrated pest management
  • Production Systems: general crop production


    Navajo tea greenthread is a native herb, with an extensive history of use among Native, Hispanic and Anglo residents of the Colorado Plateau as a favorite herbal tea, dye plant and medicinal herb. Though it is commonly wildcrafted, as an alternative herb crop it is unfamiliar among growers of the region. At my farm, however, it has proven to be a high-value crop requiring few agricultural inputs in order to thrive in the harsh, marginal agricultural lands near Gallup, NM. Once established, the herb’s demands are low for fertility, irrigation and protection from extremes of temperature, aridity and wind, resulting in a low-input crop capable of sustainably producing harvests unattainable in the wild.

    But how labor-intensive is it? As with any perennial crop, organic weed control is an issue, the default approach being hand-weeding. This project explores the effectiveness of three organic, in-row weed control methods implemented to reduce hand weeding required: the Williams Tool System’s spring tine weeder, flame weeding and the application of organic corn gluten meal.

    The spring tine implement used in the trials, the Williams Tool System, resembles a Lely finger weeder (85? bent tines) for in-row cultivation, but with the addition of a tool bar for between-row cultivators and gauge wheels. It requires the use of a tractor moving at relatively high field speed, though horsepower requirements are very low. Flame weeding was done with a backpack flamer moving at a walking pace down the row. The corn gluten meal was applied and mixed either by hand or with a drop spreader and the spring tine implement.

    My project resulted in data that compares the amount of time spent implementing each method on sample rows of the crop and time spent on the remaining hand-weeding needed before harvest. The most complete data came from the second season of the 16-month project. The spring tine implement proved as effective as properly applied corn gluten meal in keeping down the weed population and preventing extensive hand-weeding. Both reduced hand-weeding time by as much as 45%. The equipment cost of tractor and implement is much greater than the up-front investments required of the other methods, but its flexibility in timing is likely to be more attractive to the average small-scale grower than corn gluten meal. I plan to rely mostly on the Williams Tool System as my primary weed control method for my greenthread crop in the coming years.

    Project objectives:

    To conduct field trials to compare the effectiveness of three methods of organic weed control in an established greenthread field, including:

    (a) flame weeding

    (b) corn gluten meal as pre-emergence organic herbicide

    (c) mechanical, in-row cultivation using a spring tine weeding implement

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.