Above Ground Root Collar Excavation

Evaluate and mechanize Above Ground Root Collar Excavation as a strategy to mitigate losses in peach due to Armillaria infection.

Excavated peach roots.A short-term solution to ARR diseases is Above Ground Root Collar Excavation (AGRCE), a horticultural practice that promises significantly longer tree survival on ARR-infested replant sites. In this practice, soil is removed from around the lower trunk of the tree (root collar) thereby exposing the primary roots. Following root collar excavation, the fungus retreats from already colonized roots due to drying and long term exposure to heat. Although this increases tree longevity, methods need to be refined to maintain the excavated area from continuously filling in with soil. The Schnabel lab (Clemson University) more recently developed and examined a new approach, resulting in peach trees with above-ground excavated root collars and eliminating many of the challenges of the earlier methods of root collar excavation. Pilot studies have demonstrated the potential of AGRCE for ARR management, but the larger scale commercial viability of this new planting technique must be investigated. Furthermore, the current method to excavate soil from the root collar is a difficult, labor and time intensive operation. Thus, the development of an alternate strategy to accomplish root collar excavation is critical for commercial production.

Air spade to excavate roots

The first objective is to address the need to determine and demonstrate the commercial viability of AGRCE, along with the development of a new mechanical root collar excavation system. Field trials were established throughout South Carolina in 2011 on ARR-infested replant sites. Overall tree health and performance are currently being assessed to determine the viability of the new system for commercial production. Currently, an air spade is used to excavate the soil from around the root collar (pictured left). A new mechanical system is also being evaluated to excavate the root systems in an efficient manner.

modified Levee plow preparing berm.

Grower demonstrations have been organized throughout the Southeast to educate growers on berm preparation and tree maintenance. Here, the levee plow is utilized to create the raised beds.