Cucumber (Cucumis sativus L.) accessions which had demonstrated allelopathy under controlled environmental conditions were evaluated in the field. Plant introduction (PI) 169391 suppressed proso millet (Panicum miliaceum L.) fresh weight and population 58 and 84%, respectively. Total overseeded and volunteer weed population was reduced 54% when grown in association with PI 169391. Plant introduction 169391 was approximately twice as effective as PI 285605 in suppressing proso millet growth. Inhibition of weed species did not occur consistently in the field. The allelopathic effect of cucumbers was suppressed during periods of increased rainfall. However, these tests demonstrated that allelopathic activity could be obtained under certain edaphic and environmental conditions.
