Clammy cuphea

Clammy cuphea (Cuphea viscosissima) is an annual herbaceous weed belonging to the Lythraceae family. Although sometimes studied for its oil-rich seeds, it is considered a problematic weed in agricultural settings, particularly in North American soybean and corn production fields.

The plant is distinguished by its sticky, glandular hairs that cover the stems and leaves, providing it with its common name. It typically grows in moist, open habitats, including disturbed soil areas, field margins, and cultivated crops. Its sticky nature often leads to debris accumulation, making it a nuisance during harvest operations.

The primary economic impact of clammy cuphea is its competition for vital resources such as sunlight, soil moisture, and nitrogen. In high densities, the weed significantly reduces crop yields by suppressing the early development of host plants and establishing a dominant presence in the field canopy.

Biologically, the plant is highly prolific, producing numerous seeds that can persist in the soil seed bank for several years. Germination usually occurs from late spring through summer, allowing the weed to emerge consistently even after early-season control measures have been applied.

Integrated management is essential for effective control. This includes deep tillage to bury seeds, rotating crops to disrupt the life cycle of the weed, and the application of post-emergence herbicides. Pre-emergence chemical treatments are also highly recommended to prevent the initial establishment of cuphea populations in sensitive crop fields.