Orobanche crenata is a major constraint for winter pea production in Mediterranean and East Asian countries. Screening for resistance performed under field conditions in 20 field pea cultivars showed that very low levels of genetic resistance were available. The resistance proved to be highly influenced by environmental conditions and needs to be supplemented with other control measures. Infection is greatly reduced in later sowing being highest in plots sown by October-December, and much reduced in plots sown by January-February. Imazethapyr applied pre- and post-emergence of the late crop sowings significantly reduced the infection and increased yield. (C) 2003 Elsevier Science Ltd. All rights reserved.