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Potential increases in the yield of agronomic crops through enhanced light interception have led many growers to consider using narrow rows in lima bean (Phaseolus lunatus L.). However, no information is available on how narrow row spacing affects weed management or fits into an integrated pest management strategy. To address this, field studies were conducted in Delaware and Maryland in 1996 and 1997 to evaluate the effects of row spacing (38 vs. 76 cm) on weed control, and on yield and quality of lima bean. Weed management inputs were also evaluated with labeled or reduced pre-emergence rates of metolachlor plus imazethapyr applied broadcast or banded. Only 76-cm rows were cultivated according to the standard practice for this production system. In general, row spacing, herbicide rate, and herbicide application method had no effect on lima bean biomass or yield, on weed density, control, or biomass production, or on economic return. However, weed control consistency was improved when wide rows were used, even with reduced herbicide rates, possibly because of cultivation. Using reduced herbicide rates and band applications resulted in 84% less herbicide applied without affecting weed control. Chemical names used: 3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide (bentazon); 2-[4,5-dihydro-4-methyl-4-(1-methylethyl-4-(1-methylethyl)-5-oxo-1Himidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid (imazethapyr); 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); 2-[1-(ethoxyimino)butyl]-5-[2-ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one (sethoxydim).

Mustard seed meals of indian mustard [InM (Brassica juncea)] and yellow mustard [YeM (Sinapis alba)], alone and combined, were tested for effects on tomato (Solanum lycopersicum) plants and for suppression of southern root-knot nematode [RKN (Meloidogyne incognita)] and weed populations. In the greenhouse, with all seed meal treatments applied at 0.25% total w/w soil, low tomato plant stands (up to 60% dying/dead) resulted from amendment with 3 YeM:1 InM, 1 YeM:1 InM, and YeM, applied right before transplant. Compared with untreated controls, low numbers of RKN eggs per gram root were consistently recorded from amendment with 3 YeM:1 InM. In a 2012 field study, incorporation of 1 YeM:1 InM (1700 lb/acre) resulted in lower tomato root biomass than fertilizer application (504 lb/acre), YeM or InM (each 1700 lb/acre). All treatments were applied with added fertilizer to achieve 100–102 lb/acre nitrogen, 7.4 lb/acre phosphorus, 74.7 lb/acre potassium, 6.0 lb/acre sulfur, and 1.0 lb/acre boron. The lowest numbers of RKN eggs per gram root (harvest 2012) were collected from plots amended with InM (1700 lb/acre), YeM (850 lb/acre), and 3 YeM:1 InM (1700 lb/acre), but the numbers were not significantly different from fertilizer only (504 lb/acre) controls. Highest and lowest tomato yields (numbers of fruit) in 2012 were recorded from YeM (850 lb/acre) and 3 YeM:1 InM (1700 lb/acre) amendments, respectively. In 2013, there were no significant differences among treatments in eggs per gram root or in tomato yields. No mustard seed meal treatment affected weed populations. At the tested rates, YeM seed meal showed potential for use in tomato beds but results were inconsistent between years.