by LUIS RODRIGUEZ, UF/IFAS Polk Extension
Agricultural crops are susceptible to damage from a wide range of pests, including weeds. Among the most troublesome weed species are purple and yellow nutsedge, which can significantly reduce yield efficiency in many crops, including strawberries.
What Are Purple and Yellow Nutsedge?
As their names indicate, purple and yellow nutsedge are sedge weeds characterized by triangular stems and leaves arranged in three distinct ranks. Because of their similar appearance, sedges are often mistaken for grassy weeds, and if not properly identified, this can lead to the selection of ineffective or inappropriate Integrated Pest Management (IPM) strategies.
Purple and yellow nutsedge are perennial weeds, meaning that without effective management, they are likely to persist in the areas they infest. These species occur in both warm and temperate regions and can invade a wide range of environments, including landscapes, gardens, fields, crop land, and pasture fields. They are particularly problematic in agricultural systems, as they have the ability to penetrate plastic mulch used in the production of crops such as strawberries.
Yellow nutsedge is characterized by lighter yellow‑green foliage and yellow flower heads, whereas purple nutsedge has darker green leaves and reddish‑purple to brown flowers. In general, purple nutsedge is more difficult to manage than yellow nutsedge because it forms extensive chains of deep, long‑lived tubers that readily regenerate following control efforts.
Control Methods
Nutsedge is best controlled in strawberries by combining several Integrated Pest Management methods into a single, long-term strategy. Because this weed is perennial and spreads quickly, growers need to manage it all year-round; otherwise, populations can rebound rapidly and become widespread. Below are several management options to consider:
Fumigants – Fumigation can help manage nutsedge in fields where it has been a recurring problem, though results are not always consistent. Studies in Florida show that fumigants combining 1,3-dichloropropene and chloropicrin work better than using either product alone. Control improves further when this mix is paired with KPam® or Vapam®, known as the Florida 3-Way system. Getting even distribution is key, and methods like mini-coulter rigs or multiple drip tapes help prevent poor control along bed edges. Using TIF mulch also boosts fumigant performance compared with standard plastic films.
Before transplant – Nutsedge emerging through plastic mulch can be managed with directed applications of glyphosate, while pre-emergence herbicides applied in row middles can help suppress additional weed emergence.
In the Crop – Targeted herbicide applications are the most effective method for managing weeds, including nutsedge, within plastic-mulched strawberry rows. While hand weeding can provide short-term suppression, nutsedge readily re-emerges due to its ability to regenerate from underground tubers.
Postharvest – As previously noted, effective nutsedge management requires year-round attention. Even after harvest, the use of pre-emergent or post-emergent herbicides, as well as fumigants, can help growers reduce nutsedge populations and minimize infestations in the subsequent growing season.
Fallow Period – Cover crops are a recommended practice for fallow fields in Florida. However, although cover crops can suppress nutsedge growth, they will not reduce the overall population size. For this reason, it is also recommended to use rotating cultivation with glyphosate applications as the most effective way to reduce tuber density in the soil. Cultivation will break the rhizomes that the tubers are attached to and maximize nutsedge emergence. The emerged nutsedge can then be controlled with glyphosate applications.
Suppress Nutsedge to Minimize Impact
Purple and yellow nutsedge are persistent, difficult-to-manage weeds that can significantly reduce strawberry yields if not properly controlled. Because these perennial sedges spread rapidly through underground tubers and can penetrate plastic mulch, effective management requires accurate identification and a year-round, integrated approach. Combining fumigation, targeted herbicide applications, cultivation, and postharvest and fallow-period management practices offers the best long-term strategy to suppress nutsedge populations and minimize their impact on strawberry production.
For more information about nutsedge management, please access the following “Ask IFAS” publications:
Management of Purple and Yellow nutsedge in Florida Strawberry
Luis Rodriguez is the Polk County Small Farms and Pesticide Education Extension Agent. You can reach him at lrodriguezrosado@ufl.edu or 863-519-1049.