Ornamental willow growth response across five concentrations of controlled-release fertilizer

Abstract

Growth response of five ornamental willows (Salix), with sales potential for the cut-stem industry, was assessed in a 1-year container trial studying various concentrations of fertilizer. Plants were grown in 3-gal nursery containers fertilized with five concentrations of 18N-2.6P-6.6K controlled-release fertilizer (100-day release period) with micronutrients, applied as top dressings at 0, 10, 20, 40, and 60 g/container. Yield data were collected on the commercially important parameters including total stem length, stem quantity, and fresh weight of stems. Additional effects of fertilization on the timing of tip abscission and floral bud burst were also evaluated. Total stem length and fresh weight increased for all willows in the fertilized treatments compared with control; however, treatments above 40 g/container did not result in an increase of these parameters. Kori-yanagi willow (S. koriyanagi) had the highest yields across all treatments of fertilization. Fertilizer applications extended the period of stem elongation by delaying tip abscission for all willows, and for 'The Hague' willow (S. gracilistyla × S. caprea) tip abscission was delayed by 44.0 days at 40 g/container treatment compared with control. Floral bud burst dates, which differed greatly among willows, were unaffected by applications of controlled-release fertilizer.