Weed Watchers


Citizen Scientists to Report Season’s First Sighting of Noxious Weeds

We are tracking the emergence behavior of three noxious weeds this spring, Mugwort (Artemesia vulgaris), Japanese Stiltgrass (Microstegium vimineum), and Crabgrass (Digitaria spp.).                 

Become a Weed Watcher and help us track these weedy villains!

How you can become a Weed Watcher

We are interested in WHEN these weeds emerge on Long Island.  When you FIRST see them in spring-

Snap a photo and email it to us along with this info:

  • Date photo was taken
  • Location (physical address or GPS coordinates)
  • Habitat where weed was growing (lawn, landscape bed, roadside, etc.)

Send to Andy Senesac, afs2@cornell.edu


Look for it Mid March through April

Rhizomatous perennial, reproduces by rhizome or seed

Mugwort leaves resemble mugwort leaves Mugwort emerges

Leaves resemble chrysanthemum

Leaves silvery on bottom, green on top
Emerges early in spring


Look for it Early April to Early May

Sprawling annual grass that appears a few days before crabgrass

Stiltgrass leaves
Stiltgrass seedlings
Stiltgrass looks similar
Leaves 2-4" long

Broad, round-bladed seedlings can be mistaken for broadleaf plant

Looks similar to crabgrass but has shorter leaves


Look for it Late April through May

Summer annual grass that spreads by seed and root nodes

                crabgrass til2
    crabgrass skel2

Germinating near weed skeletons

Last updated November 14, 2019