This article has been published in the 2000 April issue of Prairie Star
Integrated weed management (IWM) systems allow producers to implement strategies effectively in an economically and environmentally sound manner. The steps included in an IWM system are prevention, scouting, implementing a weed management plan, preparing rescue treatments in case the plan fails, and evaluate the effectiveness of the weed management plan.
Prevention is the most cost-effective component of an IWM system. Investing time in preventing weed invasion now decreases the amount of time and money involved in weed control in the future.
The prevention component of weed management involves the following: 1. prevent the introduction of new weed species into fields, 2. manage weeds in field margins, irrigation ditches, rights of way, and adjacent areas and 3. prevent current weeds from reproducing.
The classic idea of prevention is if you don’t have it, don’t get it. Planting clean seed is key to preventing new weeds from invading. In addition, clean tillage and harvest equipment when exiting fields infested with weeds.
Buying certified seed is one method to minimize the planting of weeds with seed. Certified seed is field inspected, tested for purity and germination, true to variety, conditioned through certified facilities, and quality assured. The Montana Seed Growers Association inspects seed production fields for weed seeds that are inseparable from the desired crop seed. . No jointed goatgrass or Persian darnel plants are allowed to be present in certified seed production fields.
For example, only 5 wild oat plants are allowed per acre in seed fields. Currently, the Montana Seed Growers Association has zero-tolerance for jointed goatgrass, wild oats, and Persian darnel in seed samples. Zero-tolerance means that they will not certify seed if just one wild oat, jointed goatgrass, or Persian darnel seed is found in the seed sample. For more information on the Montana seed law and other seed standards contact the State Department of Agriculture or the Montana Seed Growers Association. Certified seed is often slightly more expensive than non-certified seed; however, spending more money initially may reap long-term benefits in that less money will be spent controlling weeds introduced by contaminated seed.
Growers that use non-certified seed, should know the seed source. If the source is a neighbor, ask to inspect the field for weeds not present in your fields and weed escapes. Be particularly aware of weeds such as jointed goatgrass, Persian darnel, redstem filaree, fumitory, or other hard to control weeds. If you use your own source, hand-weed the seed field to ensure it is weed free. Additionally, take seed to cleaning plants to remove weed seed. Remember this seed will be spread across the entire seed acreage and controlling weeds by not planting them will be cheaper than spraying them later.
Also, to avoid introducing new weed species into fields, do not haul weed-infested straw or hay to areas where the weed is not present. If you must transport seed, straw, or hay cover the load to prevent weed from blowing off the truck. Furthermore, hay brought on to public land must be certified weed free. This is a law in Montana.
Finally, grind screenings and other by-products before feeding them to livestock. Grinding alone does not ensure that all weeds are eliminated from the feed. Pellet processing in addition to ground screenings is recommended in order to thoroughly clean the feed. It is thought that velvetleaf invaded the Yellowstone River Valley through contaminated feed screenings from the east. For more information on certified hay and other feed contact the Certified Hay Producers.
Manage weeds in field margins, irrigation ditches, rights of way, and adjacent areas to minimize further spread of these weeds throughout fields. Several options exist for managing neighboring areas including mowing, using selective herbicides, and planting barriers such as sod or mixed grasses.
Preventing already-established weeds from reproducing requires action at both the seed and the vegetative level. Annual plants reproduce by seed, whereas perennial plants reproduce by both seed and vegetative parts such as the roots. Completely preventing weeds already introduced in fields is impossible. The goal is to use current weed management practices to minimize the reproduction and spread of weeds. The challenge is to make short-term inputs improve economic return over the long-term.
Minimizing seed set may require management actions that will not protect against crop yield loss in the short-term, but increase long-term management as well as profitability of the system. For example, applying Roundup to escaped weed patches, such as jointed goatgrass, Persian darnel, wild oats, or kochia. Post-harvest management may also be required to prevent seed set by weeds that continue to grow after harvest (i.e. Russian thistle, kochia).
Further research needs to be conducted to quantify the costs and benefits of preventative measures for long-term management. Intuitively, investing time and money into preventative measures should ensure against increased future management expenses.
Categories: Weed, Integrated Weed Management, Jointed Goatgrass, Kochia, Persian Darnel, Russian Thistle, Velvetleaf, Wild Oat
Date: 04/28/2005