Wells and streams in 10 North Dakota counties were surveyed for picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid), the major herbicide used to control leafy spurge (Euphorbia esula L. # EPHES). Three rivers and 144 wells were sampled in 1985. Picloram concentration ranged from <0.1 to 12.4 ppb in the water from five wells in five counties and from <0.1 to 6 ppb in two rivers. An additional 44 wells were sampled in 1986; they were located within 2 km of the five wells where picloram was detected in 1985. Picloram concentrations in 1986 ranged from non-detectable to 6.7 ppb in the original contaminated wells and was 0.97 ppb in water from one of the additional 44 wells. Picloram concentration in the river water was lower in 1986 than in 1985 but was detected farther downstream. All contaminated wells were within 1.5 km of an area treated for leafy spurge, but picloram had been spilled accidentally or misapplied near all but one of the wells. The concentrations detected were at least 100 times below suggested tolerance levels for water.

Strategies to prevent chemical contamination of groundwater will be more effective and cost less than cleaning up groundwater. Advances in weed control technologies have improved timing of herbicide applications, have reduced application rates from kg/ha to g/ha, and have distributed herbicides better within the weed-crop complex. These technologies include microbial pesticides, controlled-release formulations, herbicide chemistry, improved integrated weed management systems, and bioeconomic weed-crop models that reduce herbicide use. These new technologies should reduce the quantity of herbicides used by farmers and lessen the chances of groundwater contamination.

When Scotland was under an imminent Viking invasion, the Scots piled the beaches with thistles and waited. During the night of the invasion, the sandal-clad Norsemen leaped onto the thistle-strewn beach and let out cries of pain and curses. Warned of their approach, the Scots drove the Norsemen back to their ships. Small wonder that the thistle became Scotland's heraldic emblem and the source of her motto, “Touch Me Who Dares”. Since 1687, induction into Scotland's Order of the Thistle has been a great honor. Linnaeus named Scotch thistle, Onopordum acanthium L. # ONRAC, from the Greek onos, or donkey, and perdo, to consume; the species name is from the Latin acanthus, meaning spiny. Thus it is a spiny plant eaten by donkeys.