Weed control in sweetpotatoes

Abstract

The sweetpotato (Ipomoea batatas (L.) Lam) crop, once established, requires little field management apart from weed control. Currently, weeds are minimised by a combination of hand-weeding, inter-row cultivation and the application of paraquat (100 g ai/ha) over the crop. In this study, alternative herbicide treatments were examined in a field trial. Hand-weeding produced the highest marketable yield (26.7 t/ha), significantly more than all other treatments apart from acetochlor (2.4 kg ai/ha), which produced 21.8 t/ha (P< 0.001). Weed numbers were significantly reduced to 3.5% (acetochlor) and 16.2% (paraquat) of the unweeded plots (P< 0.001). There was a strong negative relationship between early weed count and final total root yield (R 2 = 84.0%).

Identification of paraquatresistant <i>Solanum nigrum</i> and <i>S americanum</i> biotypes

“…Lewthwaite, unpubl. data), a much higher level than the 1.1% previously observed in a non-problematic field with a similar cropping background (Lewthwaite & Triggs 2000). If allowed to mature to flowering stage, S. nigrum plants from the poorly controlled field tended to display a more compact growth habit than those from other areas.…”

“…Sweetpotato growers in the Dargaville-Ruawai region became increasingly aware that their standard weed management techniques, based on the herbicide paraquat, were not controlling S. nigrum. Growers typically apply paraquat over the establishing crop at 100 g ai/ha (Lewthwaite & Triggs 2000). A survey conducted on a cultivated sweetpotato field with a history of poorly controlled S. nigrum estimated that this species comprised 46.9% of the weed composition (S.L.…”

“…Generally, low rates of the contact herbicide paraquat are applied repeatedly over the crop during early sweetpotato field establishment, until the sweetpotato plants are capable of forming adequate ground cover. Each paraquat application destroys successive batches of newly emerged seedling weeds, leaving the hardier sweetpotato transplants relatively unharmed (Lewthwaite & Triggs 2000). Paraquat acts in the presence of light, so sweetpotato growers apply the herbicide at dusk or early dawn to improve its selectivity for weeds within the crop.…”

A flora of agricultural and horticultural crops : a quick scan of selected crops in the Mekong Delta

“…Weeds are reduced to a minimum by a combination of hand-weeding, inter-row cultivation and the application of Paraquat (100 g ai/ha) over the crop. According to Lewthwaite and Triggs (2000) the herbicide Acetochlor shows a good control of the weed population without affecting sweet potato yield or quality, however Paraquat causes damage to sweet potato plants, although it effectively controls some weed species while other species, such as fathen, are not controlled [72].…”

Response of sweetpotato to pendimethalin application rate and timing

“…Although extensive research is available on PRE and PPI applications of pendimethalin in a variety of cropping systems, limited data are available regarding its effect on sweetpotato growth and root development. Lewthwaite and Triggs (2000) reported no injury to sweetpotato plants from pendimethalin applied at 990 g ha −1 1 d after transplanting (DAP) in New Zealand. The use of pendimethalin in sweetpotato would be beneficial to growers because it controls broadleaf weeds including Palmer amaranth and annual grasses.…”