Experimental orchard at Lansing NY: The trial compares four different ground cover management strategies in the apple tree rows, pre-emergence herbicide application, postemergence herbicide application, biannual bark-mulch application and a mowed grass cover. Over the past 13 years, both herbicide treatments lead to reduced soil-organic matter content in the upper soil layers, whereas mulch application more than dublicated the soil organic matter content. Presently we are conducting seedling-biotests to evaluate the effect of the groundcover management on the ARD-complex.