Hilling is the only Tillage operation necessary in the production ofpotatoes. The objective of hilling is to cover the daughter tubers with sufficient soil to prevent, minimize infection with late blight, minimize frost damage, improve drainage in the area of tuber formation and to facilitate harvest. Rotary hose, discs, mouldboards, or power hillers equipped with a metal mould are commonly used to shape loose soil into a hill. The hilling implement should be adjusted to produce a wide, flattened hill ideal forprotecting the tubres from sunlight, late blight spores and frost (figure 3.6-5). To effectively control weeds, hilling must take place before the weeds get past the two true leaf stage. Hilling can be performed pre or post emergence. Regardless of the hilling implement used, emerged plants should not be covered with soil. This sets the plants back and delays growth. It is recommended that power hilling be carried out prior to emergence to avoid covering the plants. Post-emergent hilling, other than power hilling, should be completed before the plants are 8 inches (20 cm) in height to avoid damage to the roots and foliage.