Ambrosia artemisiifolia

Ambrosia artemisiifolia, commonly known as common ragweed, is an aggressive annual weed native to North America that has become a major invasive species in Europe, Asia, and parts of Australia. It is easily identified by its deeply lobed leaves and inconspicuous green flowers, which produce vast amounts of pollen known to cause severe allergic reactions and hay fever in humans. Ragweed thrives in disturbed soils, roadsides, agricultural fields, and construction zones, where it quickly colonizes and spreads.

This weed is especially widespread in the United States, Canada, Central and Eastern Europe, China, and parts of Russia. Although it is generally classified as a single species, regional populations exhibit ecotypic variation in height, leaf shape, branching patterns, and flowering time—traits that reflect local environmental adaptations but do not constitute formally recognized subspecies. Some variants are more competitive in arid zones, while others dominate in temperate climates with rich soils.

Ambrosia artemisiifolia significantly affects crops such as soybean, sunflower, corn, and various vegetables by competing for nutrients, water, and light, leading to yield reductions. Its early emergence and rapid growth make it difficult to control, especially in no-till farming systems. Management typically involves crop rotation, mechanical tillage, and selective herbicides, while biological control efforts—such as introducing leaf beetles—are being explored to curb its spread in regions like Europe and Asia.