Welcome to the University of Georgia Weed Science Homepage.
The occurrence of herbicide resistance in Palmer amaranth and other weeds in Georgia is cause for
significant concern for the agricultural industry. Changes in cropping practices, specifically the
reliance on a limited number of herbicides, have streamlined weed management. However, the consequence
has been the development of herbicide resistance. An effective herbicide-resistant weed management plan
will require the integration of multiple herbicide chemistries in an effort to minimize selection
pressure and delay the occurrence of herbicide resistance in a field. Other control strategies, such as
tillage, extreme cover crops, narrow row spacing, hand-weeding, crop rotation, and mechanical cultivation
must also be included in an herbicide resistant weed management plan.
Effective alternatives to methyl bromide exist but selecting the ideal fumigant, mulch, and herbicide
program is challenging. Growers must better understand how soil texture, moisture, bed compaction, and
their cultural practices influence fumigant activity, planting intervals, and off-gassing concerns.
This circular is provided to assist growers with developing the most effective fumigant system for their farm.
Ryegrass threatens Georgia wheat production, with numerous populations resistant to Osprey, PowerFlex,
Axial and Hoelon. Aggressive resistance management programs must be implemented to ensure long-term
sustainability of grain production.
Crop rotation, tillage, and a sound herbicide program are all often critical components for long-term
success. This ciruclar focuses on developing sound herbicide programs while minimizing crop injury
for the following production systems: 1) transplanting into mulch, 2) transplanting into bareground,
and 3) seeding into bareground.
New herbicidal tools are being developed to assist growers in the battle against weeds in watermelon.
These tools are a result of cooperative efforts involving The University of Georgia, IR-4, The Georgia
Department of Agriculture, The Georgia Agricultural Commission for Vegetables, and Industry. This circular
is an effort to provide effective weed management programs for seeded and transplant watermelon.
It is imperative that growers continue to use
sound herbicide programs but also
integrate these programs with other control
measures, such as hand-weeding, to remove
escapes before seed are produced, deep turning
to reduce the number of plants emerging (ideally
wait 3.5 to 4 years before repeating), and/or
using a heavy mulch cover crop to suppress
emergence in conservation tillage systems.
Palmer amaranth is a highly competitive weed of field corn, cotton, peanut, and soybean and has been confirmed to be
resistant to glyphosate in nearly every agronomic county in GA. Glyphosate-resistant (GR) Palmer
amaranth’s establishment and spread has been assisted by its rapid growth rate, extensive rooting structure, high seed
production, physical seed movement (man, animal, water), and most importantly by pollen (wind) dispersal.
Tropical spiderwort is a noxious, exotic, invasive
weed that can spread quickly. Upon initial
observation, tropical spiderwort appears to be a grass. While not a grass, it is a monocot (in
contrast to broadleaf weeds, which are dicots) with
leaves and stems usually fleshy and succulent. The
stems will creep along the ground and root at the
nodes. Vegetative cuttings from stems are capable
of rooting and reestablishing following cultivation.
Tropical spiderwort will produce seed above and
We are continually adding new information to our website.
This website may contain research results of use patterns of herbicides, some of which may not be currently registered for the particular use. Such results are included for informational purposes only and should not be taken as recommendations for use. Additionally, the University of Georgia does not guarantee nor warrant the standards of the products, nor do they imply approval of the products to the exclusion of others which may be similarly effective. Official University of Georgia weed control recommendations can be found in the latest edition of the Georgia Pest Control Handbook (Special Bulletin #28).