Crop growth habit complements weed management effects on weed emergence and growth patterns. In particular, pendimethalin-based integrated weed management systems (P-IWM) are beneficial in both okra [Abelmoschus esculentus (L.) Moench cv. Jokoso] and Indian spinach (Basella alba L.). This study compared the preliminary influence of P-IWM systems, namely P1 (pendimethalin at 0.33 kg a.i./ha applied pre-emergence, PE), plus weeding once at 3 weeks after sowing (WAS) (P1 + W3), weeding once at 5 WAS (P1 + W5), or PE atrazine at 2.05 kg a.i./ha (P1 + A1), P1 alone, weeding once at 3 + 5 WAS (W2) and no weeding (Wy), on relative weed growth in okra and B. alba in a humid tropical environment. A randomized complete block design using three replications per treatment was used. Both crops compared well in ecological weed growth, in terms of weed dominance/relative importance value (RIV) and diversity (H’). However, weeds were slightly more important, diverse and varied more widely with P-IWM in okra than in B. alba. Okra had distinctly more weed associates (58.8%) and perennial weeds (20%) than B. alba (41.2 and 7.1%, respectively) during crop establishment. Annual broadleaves and grasses were considerably more in B. alba (64.3 and 28.6%, respectively) than in okra (50 and 25%, respectively). Weed associates of crops were diverse but Synedrella nodiflora was distinctly persistent in both crops and more important in B. alba (RIV= 42.5%) than in okra (33.1%). It is concluded that differences in ecological weed growth arising from P-IWM were due to crop growth habit, especially canopy cover.

Key words
Vegetables, IWM, pendimethalin, growth habit, weed flora

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