Integrated pest management resources for Michigan Michigan State University home IPM Michigan home
Weed Identification in Christmas Trees

Search
Resources
bulletChristmas trees
bulletField crops
bulletFruit
bulletHome and yard
bulletNursery and landscape
bulletTurfgrass
bulletVegetable

Related pest diagnostic/management programs
Diagnostic Services ● Soil/Plant Nutrient Lab ● Enviro-weather ●Regional IPM Center ● Pesticide safety ● Organic: New Ag Network ● Invasive species ●Sustainable ag & food systems

Organizations
MSU ANR departments ● MSU Extension ● Site index ●Contacts/permissions
Horseweed (marestail) - Conyza canadensis (L.) Cronq.
 
Horseweed rosette
Horseweed rosette.
Horseweed flowers
Horseweed flowers.
Life cycle: Erect winter or summer annual.

Leaves: Cotyledons are egg- to spatula-shaped and hairless. Seedling leaves initially develop from a basal rosette; mature leaves are alternate and numerous, and crowded along an erect central stem. Leaves are hairy and linear to lance-shaped with smooth to toothed margins, gradually becoming smaller toward the top of the plant.

Stems: Erect, hairy central stem arises from a basal rosette, then branches to flower, reaching up to 7 feet tall. Flowering branches resemble a horse’s tail.

Flowers and fruit: Numerous clusters of small, white flower heads are found on many short branches near the top. Each seedhead is capable of producing thousands of small seeds; each seed is enclosed in a single-seeded, wind-disseminated fruit.

Reproduction: Seeds.
Horseweed seedhead Horseweed plant
Horseweed seedhead. Erect central stem of horseweed.
The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the Michigan Agricultural Experiment Station, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.
Email the web developer.
Updated: 1/31/07