Objective:
Suppression from Arugula, as a green manure and trap crop, on parasitic nematodes and fungal pathogens will be quantified initially in the greenhouse and then in the field. The effect of Arugula on non-target organisms will also be evaluated. Arugula grown alone or in combination with reduced pesticide rates will be compared with traditional pesticide management strategies both from the economic and management point of view.

Approach:
Four treatments will be imposed in the greenhouse and in the field: 1) control, 2) Arugula alone (roots; foliage; and roots plus foliage), 3) pesticides alone, and 4) Arugula plus pesticides at half the commercial rate (the nematicide will be applied in some of the plots 2-3 weeks after Arugula incorporation while fungicides will be applied in the spring after potato planting). In the greenhouse study, soil cores containing nematodes and fungi, 120 in total, 20 x 144 cm in size, will be collected from the above field. Arugula grown in our fields will be incorporated in some of the cores as follows: 1) control (no Arugula or pesticides); 2) Arugula alone (only roots; only foliage; and roots plus foliage) to find out where the pesticide compounds are located; 3) Telone II at commercial rate 37.8 liters/hectare; 4) Arugula plus 1,3 dichloropropene (Telone II) (applied 2 weeks after Arugula incorporation at half the commercial rate plus Chlorothlonil (Bravo) at half the commercial rate when potatoes grow 10 cm tall. All cores will be planted to potatoes in the greenhouse and plants, soils and potato tubers will be evaluated for nematode (root knot, lesion and dagger) and fungal pathogen (Verticillium, and Rhizoctonia) damage. In the field study, arugula will be seeded in August at a rate of 7.3 kg ha-1. The experimental plots will be 3 m wide by 130 m long with treatments arranged in a randomized complete block design with 12 replications across the field. Each treatment will intersect a minimum of 25 grid locations covering the range of nematode and fungal densities occurring spatially within the field. In the end of October, Arugula will be tilled into the soil. The Arugula treatments that were found effective during the greenhouse study (i.e. Arugula roots only; foliage only; and/or roots plus foliage) will be used in the field study. The field treatments will be as follows: 1) control (no Arugula or pesticides); 2) Arugula alone (only roots; only foliage; and/or roots plus foliage); 3) Telone II at commercial rate 37.8 liters/hectare; 4) Arugula plus Telone II (applied 2 weeks after Arugula incorporation, approx. middle of November, at half the commercial rate, plus Bravo at half the commercial rate applied in the spring when potatoes grow 10 cm tall. Soil sampling will take place at Arugula pre-plant (August) and Arugula post-incorporation (October). In spring 2006, additional spatial sampling for nematodes, fungi, and soil microorganisms will be conducted to assess treatment effects on their densities prior to planting potatoes. At each grid point, 12 soil sub-samples will be obtained and combined for analysis of nematodes, fungi and soil microbes. Soil samples will be assayed for nematodes, fungi and microbes and plants and tubers will be evaluated for degree of damage by (root knot, lesion and dagger) and fungal pathogens Verticillium, and Rhizoctonia).