Be on the lookout for new watergrass in California

new watergrass species
Full plant sample of unknown water-
grass species (Echinochloa spp.). This
plant headed in late July — photos by
Whitney Brim-Deforest

University of California Cooperative Extension farm advisor Whitney Brim-Deforest has been to several farm calls in the past few weeks about an unknown grass weed.

Between last season and this, she has seen seven fields that appear to have bad infestations of a new watergrass species (Echinochloa spp.).

“We are unsure of the exact identification yet, but we know it is in the watergrass family,” she says.

The weed is maturing around mid- to late-July. It is small seeded, and the awns are long and purple.

All of the plants so far have seed heads that are completely awned, which makes it different than barnyardgrass, which has seed heads that are variably awned.

How to ID:

• Every seed head has awns (unlike barnyardgrass)

new watergrass species
Seed head of unknown watergrass species (Echinochloa spp.) Notice visible purple awns.

• Should already be headed (by mid- to late-July)

• Awns are purplish in color (see photos)

• Seeds are small (smaller than late watergrass)

Please call Whitney Brim-Deforest (541-292-1553) or Luis Espino (530-635-6234), if you suspect you have this weed in your field. They would like to collect seed samples to see what can be done to control it.

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