Synopsis Rotary hoeing performed when weeds were germinating but not emerged, and repeated once or twice at approximately 5‐day intervals, reduced weed infestations 70 to 80% and soybean stands about 10% in solid‐seeded and row‐planted soybeans. Bean yields were only slightly less than those from weed‐free plantings. When hoeing was delayed until weeds had emerged, both weed control and bean yield were impaired 50%. Wet soil conditions before or after hoeing reduced its effectiveness.

The effect of surface corn (Zea maysL.) plant residue on weed control with atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] or alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] was studied in the field and greenhouse. Plant residue did not significantly affect weed control when herbicides were applied at recommended rates but had an increased influence on control as herbicide rates were reduced. In the greenhouse, simulated rain improved the control of velvetleaf (Abutilon theophrastiMedic.) and foxtail millet [Setaria italica(L.) Beauv.].

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In spite of proven yield advantages for corn (Zea mays L.) planted in narrow rows or at equidistant spacings, equipment expense and weed control disadvantages have slowed acceptance of these cultural practices. Improving plant spacing uniformity by decreasing the intra‐row spacing variance should be as effective in increasing yields as improving spacing uniformity by decreasing row width. To aid in determining what investment may economically be made to improve intra‐row plant spacing uniformity, the effect of such spacing on individual plant yield and total yield was investigated. Yields and plant‐spacing statistics also were obtained for corn planted with V‐type runner and double‐disk furrow openers. A relationship between individual plant yield and distances to adjacent plants was developed from plants harvested individually. This relationship, combined with a frequency function of distances to plants adjacent to the harvested plant, was used to compare yields of corn from conventional plant spacings with the yield of corn from a theoretical uniform intra‐row spacing. The type of planter furrow openers investigated had little effect on yield or on intra‐row plant spacing uniformity. Intra‐row plant spacing accounted for only a small amount of the variance in individual plant yield. The study indicates that on a field scale, with corn planted in 76‐cm rows, improving intra‐row plant spacing may not significantly improve total yield. Therefore, it may not be economical to improve upon the intra‐row plant spacing uniformity obtained with conventional planters.

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