The plant has deep roots on which develop nut-like tubers 10 to 15 inches below the surface and are difficult to remove from the soil. This plant is a legume, the stems of which are 8 to 12 inches high, with a tuft of leaves at the base. The leaves are twice divided, 3 to 5 inches long, and there are usually 3 to 5 pairs of leaflets. The leaflets are oblong in shape, and from 1/12 to 1/4 inch long. The leaves have characteristic glandular dots. The flowers are of the pea-type, yellow or orange-red, and about one half inch long. The ovary of the flower is covered with peculiar tack-shaped glands. The pods are flat, about 1 to 1 1/2 inches long, and few to several seeded.
Pignut Control Practices
Control shall mean preventing the production of viable seed and destroying the plant's ability to reproduce by vegetative means.
Cultural Control Practices
Cultivation - Cultivate three to five inches deep at intervals so as to permit the weeds to grow not more than 10 days after each emergence of first plants, but not to exceed intervals of three weeks. Cultivation shall be continued until the plants have been eradicated or have been suppressed to such an extent that remaining plants may be more economically destroyed by other treatment, as the application of approved chemicals to individual plants or by hand cultivation.
Grubbing - Small infestations should be grubbed out, taking care to remove all the tuberous nut-like roots.
Herbicides Approved for Controlling Pignut
The following herbicide may be used for cost-share with landowners. Other products labeled and registered for use on this noxious weed in Kansas may be used in accordance with label directions but are not available for cost-share. Be sure to follow all label directions and precautions. For additional information consult the current KSU publication of AChemical Weed Control for Field Crops, Pastures, Rangeland, and Noncropland@.
Picloram (Tordon 22k). Restricted use pesticide. Do not apply to cropland. Follow label directions and precautions.
Biological Control Practices
There are no biological controls approved for use on Pignut at this time.