Influence of Understory Growth 

 and Quantity of Drops on the 

 Establishment of Voles in 

 Apple Orchards 



Ronald Prokopy and Jennifer Mason 



Department of Entomology, University of Massachusetts 



When abundant, meadow voles and pine voles can 

 cause severe damage to the bark or roots of apple trees, 

 sometimes causing tree mortality. Growers are well 

 aware that problems with voles can be especially great 

 during winter. 



Under second-level IPM, a strong effort is made to 

 integrate pest management practices across all classes 

 of pests, including vertebrate pests such as voles. We 

 report here on the effects on vole establishment of two 

 IPM practices directed mainly at other kinds of pests. 

 The first practice concerns management of understory 

 growth (weeds) by mowing or herbicide application. In 

 particular we wondered whether or not allowing imder- 

 story growth to remain at a substantial height during 

 autumn months would encourage vole establishment. 

 The second practice concerns picking up drops during 

 and after harvest. This practice is 

 directed primarily at reducing 

 emergence from drops of pest in- 

 sect larvae such as apple maggot, 

 codling moth, and lesser 

 appleworm. Reduction in larval 

 emergence from drops translates 

 into reduced numbers of larvae 

 overwintering within the orchard 

 and hence reduction in threat to 

 next year's crop. We wondered if 

 allowing large numbers of drops 

 to remain beneath orchard trees 

 during autumn months would 

 lead to vole establishment. 



Methods 



gust of 1993, we placed an asphalt roofing shingle (1 1 

 X 36 inches) beneath each of 10 perimeter-row apple 

 trees in each of 12 second-level IPM test blocks and 

 each of 12 nearby first-level IPM check blocks. The 

 shingles were spaced evenly around the perimeter of a 

 block. In October of each year, we lifted each shingle 

 and examined the ground beneath for signs of vole 

 establishment, either a trail or a hole into the earth. At 

 the same time, we measured the height of grass or other 

 foliage beneath the tree and categorized the number of 

 drops in a range from few to many. 



Results 



There was no detectable difference in average plant 

 height or average number of drops between second- 



In August of 1992 and Au- 



10 



Fruh Notes, Fall, 1994 



