So, what is branched broomrape? It is an obligate parasite that grows on the roots of a broad range of broadleaf plants (i.e. weeds); however, it can parasitize crop plants such as tomatoes, eggplant, potato, cabbage, sunflower, celery, bean, onions and carrots. It was first described in written material in 1753, evolving in the northern hemisphere now reaching into South Australia. It has straw colored stems lacking chlorophyll, so it is NOT green in color and is unable to conduct photosynthesis. The seeds of the plant are minute in size, so they spread like dust, and they can survive in the soil for over ten years.
Branched broomrape was first discovered in Karnes County in 1981, and it is thought to have been brought here via the marijuana drug trade. This parasitic plant occurs on roughly 1094 acres in the county, and small infestations have been located through the years in Goliad, Bee, DeWitt and Atascosa counties. This plant does not pose a serious threat to Karnes County, but it could be harmful to the vegetable production in the Winter Garden and Rio Grande Valley.
In 1982 the United States Department of Agriculture- Animal Plant Health Inspection Service (USDA-APHIS) initiated and coordinated an eradication/control strategy, which it handed over to the Texas Department of Agriculture (TDA) in 1995. TDA coordinated the project from 1995 to 1998 when they handed it over to Karnes County. Karnes County has handled the project since that time with the funding originating at the USDA-APHIS, coming through TDA then to Karnes County. Karnes County has handled the program with great diligence since the threat of full agriculture quarantine on the county if the plant were to become more prevalent. In 2008, budget cuts eliminated the funding for the program.
Governmental funding for control of this noxious weed is no longer available. Eradication is unlike since the broomrape seeds live in the soil for up to seven years. Control can be achieved by spraying a 1% rate of Glyphosate, the active ingredient in Round-Up, on its host weeds. The pesticide is translocated through the roots to the broomrape plant preventing it from setting seed. As well, some studies have shown that the broomrape particularly strikes in areas of low fertility with high weed populations. Improving fertility and promoting grass growth in affected areas will also provide a second level of control.
For any questions, comments or concerns please contact the Karnes County Extension office at (830)780-3906.