on the south and west. Ten unmanaged apple trees, 

 some annually bearing fruit, stand 200-250 yards from 

 the orchard. Insofar as possible, the orchard was 

 designed from the outset to maximize genetic-based 

 host plant resistance to pests, minimize influx of pests 

 arising from habitats bordering the orchard, and 

 maximize influx of natural enemies of pests from 

 bordering habitats. Annually, the orchard was pruned 

 in March and received lime and fertilizer based on 

 annual soil pH and leaf nutrient analysis. 



The only key apple pest in Massachusetts which 

 can be managed effectively solely through host plant 

 resistance is the fungus that causes apple scab. Ail 50 

 trees were scab-resistant cultivars: 'Liberty' (35), 

 'Prima' (5), 'Priscilla' (5), and 'Freeedom' (5). All 

 four cultivars also were sufficiently tolerant of three 

 other pathogens to obscure, over the entire study, any 

 symptoms of disease caused by them: the fungus that 

 causes powdery mildew, the bacterium that causes fire 

 blight, and the fungus that causes cedar apple rust. The 

 only exception was moderate susceptibility of Prima 

 to cedar apple rust. 



Most important arthropod pests of apple orchards 

 in Massachusetts are capable of dispersing into 

 orchards from distances of several hundreds of yards, 

 either by flight or passive wind-aided dispersal. 

 However, the majority of females of one key insect 

 pest, codling moth, was known from earlier work in 

 Switzerland to move less than 100 yards within a single 

 generation. Therefore, all unmanaged principal host 

 trees of codling moth (apple, pear, hawthorn and 

 quince) within 200 yards of the orchard perimeter were 

 removed in 1980 to create a host-free zone sufficiently 

 broad to discourage immigration of codling moth 

 females. It was also hoped that such host removal might 

 discourage immigration of lesser appleworm, which is 

 closely related to codling moth, and several species of 

 leafrollers. 



Beneficial parasitoids and predators of several 

 different apple orchard pests can provide effective 

 biological pest control when allowed or encouraged to 

 build on plants in habitats bordering orchards or on 

 understory plants within orchards before moving into 

 apple trees. Consequently, a decision was made to 

 encourage the proliferation and growth of rosaceous 

 plants (except the above) adjacent to the orchard. The 

 supposition was that plants in the same family as apple 

 (Rosaceae) would be the most likely to support non- 

 pest species of arthropods that foster buildup of natural 



enemies of apple pests, particularly of foliar pests such 

 as mites, leafminers, leafhoppers and aphids. No 

 attempt was made to manage orchard understory plants 

 in a way conducive to buildup of beneficial arthropods. 

 Beginning with the first fruit-bearing year (1981), the 

 orchard annually received a variety of practices 

 designed to minimize the impact of pests in as 

 ecologically sensitive a manner as practical. 



Arthropod management 



Several arthropod pests, active early in the growing 

 season and for which no alternative management 

 approaches were known or feasible, were managed 

 through application of pesticide. This was 

 accomplished by spraying orchard trees using a 

 shoulder-mounted, motor-driven mist blower. 

 Horticultural oil was applied annually throughout the 

 20 years at the tight cluster stage of bud development 

 against overwintering nymphs of San Jose scale and 

 overwintering eggs of European red mite. Phosmet 

 was applied annually throughout the 20 years at or 

 shortly after petal fall and again 10-17 days later, 

 primarily against plum curculio and European apple 

 sawfly. Phosmet was chosen because it afforded a better 

 combination of effectiveness against plum curculio and 

 relative safety to humans and beneficial predators of 

 apple pests than any other insecticide available in 198 1 . 

 These two annual applications of phosmet also were 

 intended to suppress larvae of green fruitworm and 

 first-generation adults, eggs and/or larvae of codling 

 moth, lesser appleworm and leafrollers arising from 

 immigrants unaffected by removal of unmanaged apple, 

 pear, hawthorn and quince trees within 200 yards of 

 the orchard. 



Apple maggot flies were managed behaviorally by 

 capturing females on unbaited red spheres, 3 inches in 

 diameter and coated with Tangletrap^"^. They were 

 deployed each year for 20 years at the rate of 1-3 per 

 tree (according to fruit load) from early July through 

 harvest. Insects and debris were removed from spheres 

 twice (at monthly intervals) until harvest. 



In an attempt to minimize within-orchard buildup 

 of codling moth, lesser appleworm and apple maggot 

 (all of which feed as juveniles inside of fruit), fallen 

 apples (drops) were picked up weekly from early or 

 mid-August until harvest and taken to a distant part of 

 the farm. 



Other than the pre-bloom spray of oil against 



Fruit Notes, Volume 66, 2001 



