NC State Extension Publications

Symptoms

Skip to Symptoms

Glyphosate (HG 9) inhibits the production of aromatic amino acids, precursors to essential plant enzymes and structures. Glyphosate is a non-selective herbicide that is applied postemergence and has no residual soil activity. Glyphosate is phloem-mobile in plants, resulting in injury being seen on new growth.

Injury symptomology includes chlorosis and necrosis. Glyphosate is phloem mobile which results in injury occurring a new growth. The development of glyphosate injury on soybeans will be a slow process. Early injury symptomology can be mistaken for nutrient deficiency. Injury will not be present on glyphosate-resistant soybean varieties (e.g. Roundup Ready), but will be evident on conventional and select glufosinate-resistant (e.g. Liberty Link) soybean varieties.

Glyphosate injury

Figure 1. Glyphosate applied to glyphosate-tolerant (i.e. Roundup Read) (Right) and glufosinate-tolerant (e.g.) Liberty Link) (Left). Glyphosate-tolerant soybeans were survived, while glufosinate-tolerant soybeans were killed.

Management

Skip to Management

Since glyphosate has no residual soil activity, non-glyphosate-tolerant soybeans cannot be injured via carry over. Injury will not be present on emerging soybean plants. Physical drift can be avoided by spraying when the average wind speed is less than 10 miles an hour and mid-day or –afternoon to avoid a temperature inversion.

Author

Extension Weed Specialist and Associate Professor
Crop & Soil Sciences

Find more information at the following NC State Extension websites:

Publication date: Jan. 11, 2021

N.C. Cooperative Extension prohibits discrimination and harassment regardless of age, color, disability, family and marital status, gender identity, national origin, political beliefs, race, religion, sex (including pregnancy), sexual orientation and veteran status.

NC Cooperative Extension prohíbe la discriminación por raza, color, nacionalidad, edad, sexo (incluyendo el embarazo), discapacidad, religión, orientación sexual, identidad de género, información genética, afiliación política, y estatus de veteran.

The use of brand names in this publication does not imply endorsement by NC State University or N.C. A&T State University of the products or services named nor discrimination against similar products or services not mentioned.

Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by NC State University or N.C. A&T State University nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your local N.C. Cooperative Extension county center.

N.C. Cooperative Extension prohibits discrimination and harassment regardless of age, color, disability, family and marital status, gender identity, national origin, political beliefs, race, religion, sex (including pregnancy), sexual orientation and veteran status.