ABSTRACT
Callus and union formation in Corylus are positively influenced by temperature. General consensus is that optimum temperature lies between 22–24°C. Under protection, Corylus are susceptible to Spider Mite, which must be controlled to avoid substantial loss of growth. Given appropriate temperature, Corylus produce copious callus and the knifesmanship involved is relatively straightforward. The genus has importance for nut production which is estimated at 600,000 tons of in-shell nuts world-wide. Hazelnuts are currently produced as bush grown plants in plantations, involving significant labour inputs for pruning and harvesting. Hazels are graftable in winter or mid- to late-summer. Winter grafting temperatures must be raised well above ambient to obtain acceptable results. Summer grafting is successful and particularly suitable for top-worked grafts for which the provision of hot-pipe conditions is difficult, and use of large poly-tents to house them during winter grafting increases heating costs.
