Boron deficiency or toxicity can reduce yield and quality of vegetables. Seven vegetable crops, varying from low to high boron requirements were grown in field plots at Corvallis in 1987. Leaf-B and yield components of green bean, cucumber, potato, carrot, tomato, broccoli and table beet were examined under conditions of fall or spring soil applied B at a 5 kg/ha rate on two soil types. Soil tests on control plots indicated B levels of .39 mg/kg and .20 mg/kg in the top 23 cm of soil in the silty clay loam and sandy loam soil, respectively. Fall or spring application of B increased soil B levels in the top 23 cm on the silty clay loam soil to .68 mg/kg and .37 mg/kg, and on the sandy loam soil to .81 mg/kg and .42 mg/kg, respectively. Boron application had no effect on yield or yield components except in green beans where spring applied B on the sandy loam reduced percent of premium grade pods (sieve sizes 1-4). Leaf-B levels were not affected in cucumber, carrot, or tomato on either soil. Boron application on both soils had a significant effect on leaf-B levels in bean, broccoli and table beet. Potato leaf-B was significantly affected only on the sandy loam soil. / Graduation date: 1993

Inter-row mechanical cultivation was proposed as a supplement to or substitute for conventional weed control methods currently used in snap bean, carrot and lettuce production. Several types of cultivators were assessed and compared. The effect of mechanical cultivation on crop yield and quality was studied by counting, weighing and grading bean pods, carrot roots and lettuce heads. The effect of mechanical cultivation on disease incidence was studied by surveying fields during the season and by determining the number and weight of diseased pods, roots and heads at harvest. The relationship between the level of Cercospora blight on carrots and potential impacts on yield was also investigated by measuring plant characteristics and the amount of force needed to separate carrot foliage from root. The effect of mechanical cultivation on the phenology of snap bean flowering was studied by determining how long it took for a plant to produce 50% of its flowers and counting how many flowers and pods a plant produced. In general, mechanical cultivation did not affect normal crop production and may be used to replace or complement conventional weed control methods. There was little variation among different cultivators within one season, but cultivator effects differed among crops and from one year to the next.

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