temperature (Table 3). In most cases, apples 

 kept in cold storage had less tunneling than 

 apples stored at room temperature. Cold stor- 

 age reduced the potential for AMF damage by 

 slowing larval growth and eventually killing 

 larvae. 



Conclusions 



From the combined results of the 1976 study 

 in New York by Reissig and this study, we 

 conclude that AMF larvae can cause at least 

 some detectable apple injury (in the form of 

 brown trails or tunnels) following essentially 

 any period when eggs are laid. For Mcintosh 

 and other cultivars ripening about the same 

 time as or later than Mcintosh, however, eggs 

 laid up to mid-July (in a growing season when 

 bloom occurs at a normal time) are less likely to 



result in detectable larval injury than eggs laid 

 thereafter. Thus, while it may be necessary to 

 treat early cultivars against AMF before mid- 

 July, it may not always be necessary to treat 

 Mcintosh or later-ripening cultivars until mid- 

 July. In most cases, placing fruit in cold storage 

 immediately after harvest will slow larval devel- 

 opment, will reduce tunneling injury, and will 

 eventually kill the larvae. In cases where apples 

 receive AMF oviposition stings, it would be wise 

 to put the apples into cold storage immediately 

 after picking and keep them there for at least 

 one month. 



References 



Reissig, W.H. 1979. Survival of apple maggot 

 larvae, Rhagoletis pomonella, in picked and 

 unpicked apples. Canadian Entomologist 

 111:188-187. 



Orchard Soils and Apple Rootstocks 



Peter L. M. Veneman and Wesley R. Autio 



Department of Plant & Soil Sciences, University of Massachusetts 



A good orchard soil is deep and well drained, 

 and yet retentive of moisture. In heavy soils 

 composed of fine particles, the spaces between 

 the particles are so small that water does not 

 drain out of the soil quickly following heavy 

 rains. Thus oxygen, which is necessary for root 

 development and growth, is excluded from 

 heavy, wet soils. Tree growth and fruit produc- 

 tion are very poor on such soils. Furthermore, in 

 soils which are composed of coarse particles, 

 water drains too quickly following rains. Trees 

 are therefore deprived of water, and under those 

 conditions tree growth and fruit production are 

 also poor. Both of these situations may be 

 modified by the grower. Poorly-drained soils 

 may be artificially drained to help alleviate 

 some of the problems, and likewise, excessively- 



drained soils can be irrigated to provide ad- 

 equate moisture to trees. Unfortunately, these 

 solutions are expensive. In many situations 

 alternative sites may be chosen, or alternative 

 rootstocks may be used which provide better 

 performance under adverse conditions. In this 

 article information provided in a previous Fruit 

 Notes article [1985, 50(3):l-4] is updated to 

 include a larger number of soils representative 

 of the entire New England region, and further 

 information on rootstock compatibility with 

 various soil types is provided. 



Size-controlling rootstocks are usually more 

 demanding than seedling rootstocks in respect 

 to drainage, depth of soil, and water-holding 

 capacity; therefore, when deciding on which 

 rootstock to use, it is very important to know the 



10 



Fruit Notes, Fall, 1991 



