Published online by Cambridge University Press: 12 January 2011
Legumes such as white lupin (Lupinus albus L.) provide a valuable nitrogen source in organic agriculture. With organic farming hectarage increasing and white lupin interest increasing in the southeastern USA due to newly released winter hardy cultivars, non-chemical weed control practices in lupin are needed. A two-year experiment was established at two locations in Alabama. Five weed control practices were evaluated: one pre-emergence (PRE)-applied herbicide (S-metolachlor), two mechanical (hand hoed) and two cultural (living mulch utilizing two black oat cultivars) weed control treatments. Fourteen weed species were encountered. S-metolachlor provided above 80% control of most weed species present in this experiment. The cultivation treatments and black oat companion crops also provided good weed control of many of the weeds encountered. Crop injury of all treatments was low on a 0 to 10 scale with 0 representing no injury: <2.0, <1.3 and <1.2 by S-metolachlor, the cultivation treatments and the black oat companion crops, respectively. Grain yield of cultivars ABL 1082, AU Alpha and AU Homer were 1540, 1130, 850 kg ha−1, respectively, when treated with the conventional treatment, S-metolachlor. Grain yield in the organic treatments was equivalent. The cultivation treatments and black oat companions were successful alternative weed control practices in white lupin production.