RUSSIAN THISTLE

"TUMBLE WEED"

Russian Thistle

"Tumble Weed" 

Salsola tragus L.

Chenopodiaceae (Goosefoot family)

 

Overview

If you've ever seen a western movie you have probably seen the stereotypical tumble weed meandering down a dusty old barren road. While great for the ambience on the big screen it is considered an extremely troublesome weed that is well adapted for the Sonoran Desert. It is responsible for spreading wildfires and can be toxic to livestock when consumed at maturity for several weeks. It can also provide a home for another agricultural pest called the beet leafhopper (Ciculifer tenellus). The beet leafhopper can cause damage to tomatoes, melons, sugar beets, and many other crops because it acts as a vector (meaning it spreads disease) for curly top diseases (members of the virus family Geminiviridae). In addition, Russian Thistle can take over fields quickly sapping crops of nutrients and sunlight, severely reducing both yields and profits.

 

Lifecycle

Russian Thistle is a summer annual but can grow essentially all year at lower elevations in arid climates. It becomes a three-foot bush at maturity in just a few months. When fully grown, it can spread thousands of seeds in long rows as it breaks off its stem, becomes a tumbleweed, and rolls across the surface of the soil. It creates seeds in only a few weeks and should be removed from your fields before it flowers. If they go to seed however, you should avoid tilling your field until they are removed by hand and discarded away from your farm or garden because these seeds can stay viable in the soil (seed bank) for decades.

 

Management

While many chemical options exist to eradicate both seeds and the plant, we don't use any pesticides in our Beyond Organic systems. Prevention is key here so we recommend placing these weeds straight into a thick yard waste bag as you hand pick them. This ensures you don't spread seeds as you walk across your field. If they haven't gone to seed yet you can just opt to use a wire or stirrup hoe and leave in the field. Flame weeding works well too for young plants if it doesn't interfere with your crops. But as a general rule its always best to remove weeds if feasible.

 

Another option is to use synthetic mulches such as tarps or agricultural fabrics over sections of effected land.  If you've already harvested your crops you can simply lay them over the whole field and use sand bags to hold them down. If crops are still in the ground just put synthetic mulches down the rows. If your crop hasn't been seeded or transplanted yet you can pre-irrigate fields with over-head sprinklers to germinate weed seeds in the weed seed bank. Synthetic mulches can then be laid over the field with drip irrigation in place to smother the weeds. Continue to drip irrigate with the mulch on top of the drip line to germinate other weed seeds. In just a few weeks the seeds in the top layer should have been germinated and terminated depending on the climatic conditions. We don't recommend using natural mulches because they are largely ineffective and can in some cases make the problem worse by trapping in heat and moisture.

 

All these management methods can be used in conjunction with each-other. For instance, you can pre-irrigate, then flame weed, and finally cap it off with synthetic mulch. Throughout the growing season you could then manage weeds with a hand-hoe. Be creative and remember the old-adage, "one year's seeding makes seven years of weeding." Happy weed hunting!