Sugar Beet - Genetic Modification - Weed Control

Weed Control

Glyphosate-resistant

The ability to effectively and efficiently control weeds in glyphosate-resistant sugar beet is one of the many reasons why glyphosate-resistant sugar beet has been widely adopted in the United States. Elimination of weeds is important in sugar beet fields because they compete with the crop for water, nutrients and light. Weeds may be chemically controlled using glyphosate without harming the crop. After planting sugar beet seed, weeds emerge in fields and growers apply glyphosate to control them. Glyphosate is commonly used in field crops because it controls a broad spectrum of weed species and has a low toxicity.

Conventional

Prior to glyphosate, growers used other herbicides to control weeds in conventional sugar beet fields. While these chemicals are still available in small quantities, they are not as effective as glyphosate and require stricter application procedures. They also tend to injure the sugar beet crop.

Since herbicide options are limited in conventional sugar beet fields, growers rely on different methods to control their weeds. One method to reduce weed populations is mechanical control. Mechanical control uses tillage equipment to move soil and disturb weeds. Tillage equipment is necessary in both glyphosate-resistant and conventional sugar beet fields, but it is used more frequently in conventional systems. This may be problematic because greater use of tillage equipment directly correlates to higher input production costs as more fuel is required to run the equipment.

In addition to greater use of tillage equipment in conventional sugar beet fields, hand labor is another useful approach to control weeds. Each year, thousands of migrant workers travel around the United States to work in agricultural fields, including sugar beet fields. The widespread adoption of glyphosate-resistant sugar beet however has decreased the demand for migrant workers. Unlike conventional sugar beet, there is greater weed control in glyphosate-resistant sugar beet fields and migrant workers are no longer needed.

Yield

According to Monsanto, "Weeds that emerge prior to or with sugarbeets cause the most yield losses" because these weeds "can compete with the crop for nutrients, soil moisture and light, therefore reducing yield and sugar content" and glyphosate-resistance sugar beets allow the use of glyphosate to kill those weeds without harming the sugar beet. One study from the UK supports that contention, while another from the North Dakota State University extension service found lower yields.

Weed resistance

Many weeds in the United States and worldwide are resistant to glyphosate. Resistance develops when growers use the same herbicide, or mode of action, every year to control their weeds. Applying different herbicide modes of action reduces the risk of resistance.

The introduction of glyphosate-resistant sugar beet may contribute to the growing number of glyphosate-resistant weeds because sugar beet may be rotated with other glyphosate-resistant crops, such as soybean. If using all glyphosate-resistant crops, growers may control their weeds every year solely using glyphosate - a weed control strategy that is not recommended because it increases the likelihood of resistance.

Monsanto has developed a program to encourage growers to use different herbicide modes of action to control their weeds in all cropping systems. Growers receive financial support when purchasing multiple herbicides.