The parasitic plant Striga asiatica (L.) Kuntze is a common weed in central Madagascar and particularly problematic in the high altitude (800-1300 meters above sea level) rainfed upland rice-maize rotation systems, where it causes serious yield losses. Soils are characterized by low organic matter content and vulnerable to high degradation (soil erosion). To kill two birds with one stone, a 3-year integrated Striga management trial was initiated in the 2011/12 cropping season, to compare the conventional cropping system, mono-crop rice-maize rotation involving seasonal tillage and crop residue removal (System 1, S 1), with three rice-maize rotation systems combining zero-tillage and annual or perennial cover crops: a rotation with rice and maize intercropped with a Vigna unguiculata-Mucuna spp. relay-crop (S2), a rotation with rice and maize intercropped with Vigna umbellata (S3), and a rotation with rice and maize intercropped with the perennial cover crop Stylosanthes guianensis (S4). In S2-S4, crop residues are not removed. Three rice varieties were tested in parallel: the locally popular, but Striga-susceptible, B22; the locally adopted, Striga-resistant NERICA 4; and the locally newly released and moderately Striga-resistant NERICA 9. The hypothesis is that combining zero-tillage with intercropping will reduce the Striga infestation rates in both rice and maize, while protecting the soil and improving its organic matter content. The use of Striga-resistant rice varieties should enhance Striga suppression in these systems. In season 1, the mean Striga densities (at harvest) in rice variety B22 were 8 times higher than in NERICA 9, and 18 times higher than in NERICA 4 (P<0.05). In season 2, the mean Striga density (at 75 days after sowing; DAS) in B22 was 5.3 times higher than in NERICA 9, and 19.3 times higher than in NERICA 4. Moreover, a spectacular carry-over effect of Striga resistance from season 1 to season 2 was observed; where maize followed rice vari