Q: Can you identify this weed for me? It has spread all over my flower beds.

A: It would have been somewhat difficult without the flower, but since you brought in a nice section of the weed along with the blue flower I was able make a better determination of the plant. Spreading dayflower, Commelina diffusa, is commonly found in ditches and in low areas where water might accumulate. Of course, this weed can also be found in landscapes receiving too much water.

This weed is particularly troublesome as it can carry the virus responsible for cucumber mosaic virus disease (CMV). This virus is found throughout the world and can infect many plants in the cucurbit family such as cucumber, squash, cantaloupe, tomatoes and peppers. If you find creeping dayflower, it would be best to remove it or chemically treat it with an herbicide to keep it in check. Aphids feeding on the dayflower can easily transmit the virus from the weed to the food crop. The symptoms can be mild in which there may be slight, twisted formations of leaves to whole plant stunting and reduction of fruit production.

In the landscape, the growth habit is somewhat similar to crabgrass but the stems are more succulent. It is often confused with doveweed but the blue flower makes it easy to distinguish. The good news – it does not tolerate foot traffic, compacted soil or mowing well. I think the best advice in a flower bed is to pull it manually and consider reducing the amount of water the flower bed receives

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