Landscape and turf professionals are being asked by their customers if there are alternatives available for glyphosate. These requests come as a result of the perceived health risks associated with glyphosate. Glufosinate, which is very similar to glyphosate as it is a non-selective, postemergence herbicide, has very different characteristics, leading to different use patterns and efficacy on specific weed types and species. The most common glufosinate products available are FinaleTM (EPA reg # 7969-444) and Cheetah ProTM (EPA reg # 228-743). Other suggested alternatives include the herbicides diquat dibromide (RewardTM: EPA reg # 7969-444) and pelargonic acid (ScytheTM: EPA reg # 10163-325). Also mentioned are several non-chemical products that contain acetic acid, clove oil, citric acid or D-limonene appearing singly and in combination. Many of these non-chemical products are Section 25(b) herbicides. These herbicides contain active and inert ingredients considered minimum risk and are registered under Section 25(b) of FIFRA (Federal Insecticide, Fungicide Rodenticide Act). They are not required to have an EPA registration number and are exempt from EPA regulations on efficacy and toxicity. The exemption from federal registration is allowed only if the manufacturer uses approved active and inert ingredients. When using an herbicide, it is very important to read, understand, and follow the product label.
|Table 1: Herbicide characteristics comparison of non-selective herbicides: glyphosate, glufosinate, diquat dibromide, pelargonic acid and the non-chemicals Section 25(b) (acetic acid, clove oil, citric acid or D-limonene).|
|diquat dibromide||pelargonic acid||non-chemicals|
|Translocation: movement within plant||strong translocation1||very limited translocation1||contact herbicide, no translocation1||contact herbicide, no translocation1||contact herbicide, no translocation|
|Effect on summer annual life cycles weeds||excellent control||fair to good control when weed is young||good control when weed is young||good control when weed is young||fair to good control when weed is very young|
|Effect on winter annual life cycles weeds||excellent control on all growth stages||fair to good control when on seedling weeds||good control when on weed seedlings||good control when on weed seedlings||fair to good control when on seedlings|
|Effect on simple/solitary perennial life cycle weeds (lacking vegetative propagation)||excellent control||fair to poor, good control when young||good control on seedling weeds only||good on seedling weeds, otherwise fair||good on seedling weeds, otherwise very poor|
|Effect on creeping/spreading perennial life cycle weeds (vegetative propagation)||excellent control||good control when on weed seedlings, otherwise fair||good on seedling weeds, otherwise very poor||good only on seedling weeds, otherwise very poor||good only on seedling weeds, otherwise very poor|
|Appropriate for turf renovation||Yes||No||No||No||No|
|Appropriate for landscape directed spray||Yes, beware of drift injury to leaves and to damaged bark on woody trees and shrubs.||Yes, drift injury risk lower than glyphosate; can cause sunken bark cankers on young thin barked plants, leaves, and damaged bark.||Yes, only on seedling and very young weeds.||Yes, only on seedling and very young weeds.||Yes, only on seedling and very young weeds.|
|Appropriate for invasive plant management||excellent on invasive plants that are controlled by this herbicide||good on seedlings only, otherwise poor||good to fair on seedlings only, otherwise very poor||good only on seedlings, otherwise very poor||good only on seedlings, otherwise very poor|
|1Translocation characteristics from Weed Science Society Herbicide Handbook, Tenth Edition 2014, published by Weed Science Society, 810 E. 10th Street, Lawrence, KS 66044-8897. ISBN 978-0-615-98937-2.|
UMass Extension recognizes that there is public debate about glyphosate. Our relevant expertise is in agriculture and horticulture, not in public health, medicine, or environmental contamination. For this reason, the information presented above focuses on known data regarding the efficacy for weed control by some active ingredients. These active ingredients are registered with the EPA and the Massachusetts Department of Agricultural Resources (MDAR) and have met the public health and environmental standards developed by those agencies. UMass Extension is committed to the principles and practices of Integrated Pest Management (IPM) and much of our research and education is dedicated to reducing the use of pesticides.
For additional glyphosate information:
US Environmental Protection Agency (EPA) - For more information on glyphosate go to https://www.epa.gov/ingredients-used-pesticide-products/glyphosate.
Weed Science Society of America (WSSA) - Founded in 1956, the Weed Science Society of America (WSSA), is a nonprofit scientific society intended to encourage and promote the development of knowledge concerning weeds and their impact on the environment. On August 9, 2019, the WSSA released a position statement paper on glyphosate, which can be viewed on the society’s website at http://wssa.net/2019/08/wssa-position-on-glyphosate.
Submitted by: Randy Prostak