“Chicle weed” primarily refers to Ambrosia artemisiifolia, widely known as common ragweed. This summer annual emerges in late spring and is a problematic garden weed. It is not associated with chicle gum production. Common ragweed is a pervasive plant that impacts gardens and human health.
Identifying Chicle Weed
Common ragweed typically grows as an erect, branched summer annual herb, reaching heights of 1 to 6 feet. Its stems are usually hairy and can range from green to light pinkish-red. The leaves are a key identifying feature, being fern-like and deeply divided, giving them a finely dissected appearance.
Young leaves may have purple speckling and are often hairy on both surfaces, while mature leaves might be less hairy. The first few pairs of true leaves are typically opposite, but subsequent leaves along the stem are arranged alternately. The root system of common ragweed is fibrous and shallow.
The flowers are small, inconspicuous, and green, appearing in late summer. Male flowers are produced in spikes at the tips of upper branches, while female flowers are found in the lower leaf axils. These male flowers release a significant amount of wind-dispersed pollen. After flowering, the plant produces small, woody, top-shaped fruits containing ridged seeds.
Where You’ll Find Chicle Weed
Common ragweed thrives in a wide range of environmental conditions, often found in disturbed areas like agricultural fields, roadsides, vacant lots, and garden beds. It is a pioneer species that prefers open, sunny habitats where competition from other plants is low.
The plant tolerates various soil textures and drainage conditions. While it grows best in warm, moist environments, it can adapt to poorer soils. Its seeds require a cold dormant period followed by light and alternating temperatures to germinate, typically emerging early in the spring. Seeds buried deeper than 2 inches generally will not germinate unless exposed to light through soil disturbance.
The Impact of Chicle Weed
Common ragweed significantly impacts human health due to its prolific pollen production. The plant is a primary cause of hay fever in late summer and early fall across North America. A single plant can produce a substantial amount of wind-borne pollen, triggering symptoms such as sneezing, runny nose, itchy eyes, and asthma in sensitive individuals.
Beyond its allergenic properties, common ragweed is a highly competitive weed in gardens and agricultural settings. Its rapid growth and early emergence allow it to outcompete desired plants and crops for essential resources like water, nutrients, and sunlight. This competition can lead to reduced crop yields and diminished vigor in garden plants.
Controlling Chicle Weed
Effective control of common ragweed involves a combination of methods, often referred to as integrated weed management. Manual removal is effective for small infestations, particularly when plants are young and before they produce seeds. Since seeds require light to germinate, burying them deeper than two inches through aggressive tillage, such as moldboard plowing, can prevent emergence. However, shallow tilling might bring previously buried seeds to the surface, stimulating new germination.
Cultural practices play a role in suppression. Mulching with a three-inch layer can prevent seed germination by blocking light. Planting competitive cover crops like fall-planted cereal rye can also suppress ragweed by shading the soil and competing for resources. Adjusting planting dates for garden plants to allow for early spring tillage or herbicide application can also reduce ragweed infestations.
For chemical control, various herbicides are available. Their effectiveness is maximized when applied to small, actively growing ragweed plants, typically under 6 inches in height. Herbicides like 2,4-D Amine are selective and can be used without harming desired vegetation when applied correctly. For resistant populations, a diversified herbicide program incorporating multiple sites of action, including pre-emergence and post-emergence applications, is recommended. Always consult herbicide labels for specific application rates and safety precautions.