Walla Walla County Extension

Weed of the Month

Puncturevine

Puncturevine (Tribulus terrestris L.) Is a summer annual; introduced from southern Europe, .5 to 2.5 feet prostrate spreading multi branching stems from base. Flowers are small, yellow, with five petals and borne in the leaf axils. It flowers and produces seed burs (goatheads) from July to October. Seed burs are two to four seeded with long woody spines. Its simple taproot, which divides into fine rootlets, allows it to take advantage of low moisture areas and/or germinate and survive in drought conditions.

Impacts: A weed that some people believe to be one of the worst weeds in the western U.S. Its sharp spines seed pods are very painful when stepped on by humans or livestock. The spines easily penetrate bicycle tires.

Control: Control is fairly good using chemicals, but eradication is difficult due to the persistence of the seed. It has the ability to remain dormant in the soil for 4-5 years. Gylosophates have had excellent results. 2,4-D has had good results.

Mechanical control measures are not very effective in that the seed will fall off plants and get buried in the soil through disturbance.

Manual control is best if you dig or pull the plant, seal it in a garbage bag and send it to the dump. Handle the plant gently as the seed pods fall off easily.