Yellow Starthistle

A very obnoxious weed with a pretty name: Yellow Starthistle (YST). This scourge on the land of the western U.S. was discovered in the Tehachapi area and BVS in the early 1990s by Chuck McCollough (founder of Triassic Legacy Winery).

In Northern California, yellow starthistle is out of control, wasting over 15 million acres of range and farm land. We do not want it to get any more out of control here. This very invasive weed is unpleasant, as it has sharp needles around each flower, which neither man nor beast should walk into. It will out-compete native and other invasive plants and weeds, as it has a very deep tap root. It will suck the soil around it dry to a dangerous extent, possibly affecting the water table. Plants bolt and flower continuously throughout the summer months, requiring constant monitoring.

I encourage you to look online to see pictures of YST at all of its stages, so that you can recognize it at its earliest stages on your property. For the earlier YST is identified, the easier it is to control.

Before flowers appear, the YST may be removed by cutting it off at ground level-I find a shovel is easier than a hoe to accomplish this. The plant may be left on the ground. However, once flowers (seed) are present, the plant must be carefully disposed of: DO NOT place it in any green waste; instead, carefully bag it so as not to drop seeds (the flower) and place the bag in the trash. I recommend accumulating it on a tarp then placing it into a trash bag.

Before many YST flowers appear, spraying with Milestone herbicide works well. Milestone is very concentrated and only takes 1 teaspoon per gallon of water in your gallon hand sprayer or 5 teaspoons in your 5-gallon backpack sprayer. Milestone is available by the quart to homeowners (Amazon for $90) or Tractor Supply online, also Abate-A-Weed in Bakersfield for somewhat more. But it is so concentrated that this quart will probably be your first and last. Once any flowers erupt, a much stronger concentration of the herbicide is required; and, when fully flowered, the plant can no longer be effectively controlled by spraying. The best solution at this stage, if hand-removal is not possible, is to mark the area of infestation with colored stakes or ribbons for pre-emergent spraying maybe just after the holidays next winter, to allow the herbicide to be watered into the ground from rain and snow to prevent the YST from ever germinating (PRE-emergent, PRE- growth).

Never mow or weed-whack YST, as the stem will be left and it will simply re-grow closer to the ground. And, if the plant is in flower, it will spread the seeds.

If you have any further questions, you may call Laurie Rude Betts at (661) 821-1904.