Extension Educationin Wharton County

What is This Weed?

 By Corrie Bowen
County Extension Agent – Agriculture/Natural Resources
Wharton County

Its common name is Bushy eryngo.  Its scientific name is Eryngium diffusum.  The Extension Office has received numerous calls in the past two weeks from landowners wanting to know what this plant is, why it’s here, and what to with it.  The fact is, there is an abundance of Bushy eryngo this season.  Bushy eryngo is nothing brand new.  It’s native to Texas and Oklahoma, and we see Bushy eryngo almost every year, but just not in the numbers that we’re seeing this year.

So why so much this year?  Well, it’s because of last year’s drought.  Following a drought, grasses can be weak and less able to compete with vigorous weeds (especially annual species).  Many describe this plant as a star thistle.  Sure, it looks like a thistle, but it’s not a thistle.  Thistles are in the Aster family.  Bushy eryngo is in the Carrot family.  The good news is that it’s an annual.  It’s common to see normally occurring annuals in abundance following a drought.  This is just one of nature’s plants of choice along the Upper Gulf Coast following last years’ drought.

Annual plants are short lived.  They complete their life cycle in one season and come back from seed.  Mowing/shredding can be beneficial in controlling annual weeds. Mowing/shredding is best utilized when weeds begin to flower, but before seed set.  Leave at two to three inches of stubble height when mowing.  Mowing is an option if Bushy eryngo is the primary weed problem.  Herbicides will be more active on annual weeds at younger stages of growth (e.g. rosette stage) than at its current stage—flowering stage.  Evaluate and identify other weed species that are present along with the Bushy eryngo. 

Although the bushy eryngo may be too mature to get effective control from herbicides right now, other weed species (e.g. Marshelder, aka Sulfaweed) may dominate and constitute the feasibility of a herbicide application to better promote grass growth for the remainder of the year.   Growth regulator herbicides with combination active ingredients such as 2,4-D + dicamba, 2,4-D + picloram, and 2,4-D + dicamba + metsulfuron are active on many annual weed species, such as Bushy eryngo.  Rates of one to two quarts per acre may be necessary to obtain a level of control.  At the current maturity stage of this plant right now in early July, the plants will soon be turning brown on their own, and they will not continue to grow this year.  Mowing these plants may be the best option this year. You might see some Busy Eryngo plants return next year. If so, spray they when they are young and green, before they turn this purple color and develop a seed head.

-30-

Corrie P. Bowen
County Extension Agent – Agriculture & Natural Resources
Wharton County
979-532-3310
cbowen@ag.tamu.edu