Leafy Spurge Control with Cultivation, Cropping and Chemicals

Abstract

T EAFY spurge is a perennial weed that is found in almost every L state north of the fortieth parallel and in the southern portions of most Canadian provinces. Heaviest infestations are found in Minnesota, the Dakotas and the Prairie Provinces. Hanson and Rudd (10) conducted extensive life history studies in North Dakota. They adopted the name Euphorbia virgata Waldst. & Kit.; however, Stevens (12), also of North Dakota, used the name 1Euphorbia esula L. two names apparently were usedl for the same species. Hanson and Rudd (10) described it as a long-livedl perennial herb, somewhat woody at the base, containing milk sap. It grows to a height of 14 to 40 inches and propagates by means of seeds and roots. Near Fargo, average plant height was 1/2 inch April 5, 1' 5 inches April 19, 31/2 inches April 23, and 121/2 inches April 30. Flowers began to appear by the end of May. This rapid early growth gives the weed a great advantage over most crop plants. The most formidable part of the plant is the root... It is well developed. large tap root begins to branch into a number of large, woody, brown-colored branches near the surface. fine roots are numerous, especially near the surface and when suitable conditions occur in deeper soil. maximum depth at which roots were found was at the water table at 8 feet. maximum lateral spread was 31/2 (10). This description is very similar to the description of the root system of field bindweed (Convolvultus arvensis L.) given by Frazier (9). main differences are that the leafy spurge root is more woody and less extensive in a clay soil than the root of a non-competing bindweed plant growing in a sandy loam soil. Pieces of leafy spurge roots as small as one-half inch long and one-eighth inch in diameter produced new shoots which grew rapidly (10). fruit is a 3-chambered capsule, explosively dehiscent, usually along the line of union of the carpels. Normally each carpel contains one seed. Nearly 50 percent of the fruits produce one mature seed, about 35 percent produce two, and 15 to 20 percent produce three. In the vicinity of Fargo, the fruits begin to ripen about July 10 and continue until September. Upon maturity the seeds are forcibly dlischarged up to a distance of at least 13 feet. In one test, they were uniformly distributed in an area extending from 1 to 13 feet from the parent plant (10). Thousands of acres of farmland are infested with leafy spurge.