What's bugging you? May 31, 2017
By Jim Leser
Published Wednesday, May 31, 2017 7:44 am
Have you ever wondered what makes a weed a weed? It is often all in the eye of the beholder. Or it could be the old realtor saying: location, location, location.
What we have today is a tale of two plants in the same plant genus. The first is Portulaca oleracea, or the common purslane weed. The second one is Portulaca grandiflora, or the desirable flower, moss rose. They both are in the Purslane family.
Common purslane is generally not much of a weed problem although I have had my fair share of them in a formerly bare moist area of my yard. It is a fleshy, prostrate summer annual with reddish colored stems. Stems radiate out in a flat rosette up to a foot in diameter, often forming thick mats with adjacent plants. Leaves are somewhat teardrop-shaped.
Yellow flowers appear singly and only open in sunshine. Black seeds are formed in capsules that resemble flower buds. Each weed is capable of producing upwards to 240,000 seeds which can remain viable in the soil for up to 40 years. Good grief!
This weed was introduced from Europe and can be a problem in cultivated fields, gardens, low-maintenance lawns, and any moist bare soil areas. The key to control this weed is prevention. Remove seedlings before they can develop flowers and hence seeds. If hoeing is used to cultivate weedy areas, make sure you remove the plants or at least allow them and the soil to dry out. Otherwise they will re-root as transplants.
Pre-emergence herbicides such as trifluralin (Treflan® or Preen®) or Pendimethalin® may be needed where a huge soil bank of seeds is found. Otherwise there are foliar post-emergent herbicides such as Trimec®, Quadmec® or glysophate. The first two post herbicides contain combinations of 2,4-D, dicamba, MCPP and may or may not include MSMA.
Really, I find that common purslane is easy to control culturally and have never had to resort to herbicides. Mulches discourage this weed. Common purslane can be used as a crunchy addition to salads and purportedly has bioprotective nutrients such as antioxidants, vitamins, and amino acids.
Lest I leave you with only a review of the weed representative of the genus, Portulaca, I am providing a photo of the summer annual moss rose, a very desirable xeric annual flower for gardens, especially rock gardens. It can be a prolific self-seeder.
If you live in the Surface Creek area, please stop by the Cedaredge Tree Board's booth at the Celebrate Cedaredge street fair June 3. We will be signing up any one who may have a tree problem and desire a free yard visit consultation on our June 17 Sick Tree Day. Our expert for the day will be Vince Urbina, CSU community forester from Grand Junction.
Jim Leser retired to Cedaredge in 2007 after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a Colorado Master Gardener.