Biology, competition, and control of smellmelon (Cucumis melo var. dudaim Naud.) in cotton (Gossypium hirsutum).

摘要

Laboratory experiments determined the optimum temperature, depth of planting, and simulated moisture stress on smellmelon germination and subsequent emergence. The optimum temperature for smellmelon germination was 30 C. Highest emergence occurred from 1 to 6 cm depths at 30 to 35 C. Smellmelon germination was 61% when the osmotic potential was reduced to -0.2 MPa and was further reduced to 48 and 7% with solutions of -0.4 and -0.6 MPa, respectively.;Field studies evaluating the competitiveness of smellmelon in cotton concluded differences in yield between 1999 and 2000. In 1999, yield reductions of 17% were observed with densities of 2 to 3 smellmelon plants per 10 m and 36% when densities were 5 to 10 plants per 10 m. In 2000, 2 to 3 plants per 10 m translated into a 26 to 31 yield losses and increased to 38---50% with densities of 5 to 10 plants per 10 m.;Additional experiments determined the critical period on competition between smellmelon and cotton. In 1999, smellmelon introduced 2 weeks after planting (WAP) did not reduce seed cotton yield. Cotton competed with smellmelon until 6 WAP without a yield loss. In 2000, smellmelon introduced 2 to 4 WAP reduced seed cotton yield 30--32% and by 4 WAP reductions were less than 5%. Smellmelon competing with cotton 2 WAP reduced seed cotton yield 24% and were further reduced 32 to 55% by 4 to 14 WAP.;Experiments evaluating different herbicides and application timings for smellmelon control indicated that glyphosate, pyrithiobac, and fluometuron + MSMA controlled 5 to 15 cm smellmelon 97%. Glyphosate only controlled 38% of smellmelon with 45 to 60 cm stem lengths. Control of larger smellmelon also decreased with fluometuron + MSMA to 72% but increased to 83% with pyrithiobac.;Experiments evaluating the effect of herbicide and crop rotation indicated that low input herbicide systems might not control entireleaf morningglory adequately at the end of three years. However, those systems including preemergence herbicides and postemergence applications of glyphosate controlled johnsongrass, entireleaf morningglory, and smellmelon each year. These studies also suggested that higher cotton yields are possible by including corn for at least one year in the rotation schedule.