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The mature leaves of 38 apple (Malus domestica Borkh.) (Rosaceae) cultivars were screened for resistance to laboratory colonies of Epiphyas postvittana (Walker) and Planotortrix octo Dugdale (Lepidoptera: Tortricidae) by measuring larval survival and development rate, and pupal weight, in no‐choice laboratory bioassays in early summer. There were few cultivar effects on larval mortality but Nevis 1, A40R04T119, and ‘Sir Prize’ reduced survival of E. postvittana. Effects on development time and weight were correlated, and were integrated into a single measure of resistance Rc. Rc varied greatly between cultivars for both leafroller species, and identified 15 and 11 cultivars with partial resistance to E. postvittana and P. octo, respectively. A further experiment with three of the cultivars in midsummer, using the laboratory colonies in comparison with new colonies (from field collected larvae), produced similar results for E. postvittana, but there was no survival of new colony P. octo larvae on two cultivars. These results for P. octo are consistent with other recent research showing extreme cultivar resistance and critical colony and seasonal influences. A series of 4‐year field trials with the 38 cultivars showed poor correlation between laboratory and field resistance for the dominant leafroller species in the field, E. postvittana. The combined data, however, identified ‘Red Dougherty’, ‘Sir Prize’, and A40R04T119 as potentially useful in breeding for resistance to this species. The implications of these findings for integrated pest management (IPM) programmes and for the breeding of leafroller‐resistant apple cultivars are discussed.

Apple leafcurling midge (Dasineura mali) (ALCM) can seriously damage apple tree leaves. Insecticides may be applied to the soil in spring to kill ALCM emerging from overwintering sites. ALCM emergence was studied in the Waikato, Hawke's Bay, Nelson, Canterbury and Central Otago over two seasons (1998/99 and 1999/ 2000) using cages placed over the soil beneath apple trees. ALCM and its egg parasitoid (Platygaster demades) emerged over a similar period of time. Emergence in southern districts began later and over a shorter period. A single soil treatment with diazinon, reduced the numbers of ALCM emerging from treated soil, but also very few P. demades emerged.

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