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INTEGBATED PEST MANAGEMENT AND BIOLOGICAL CONTROL POTENTIAL 

 FOR STRAWBERRIES IN THE NORTHEASTERN UNITED STATES 



David T. Handley 

 University of Maine 



Strawberry producers in the northeastern United States are faced with a 

 number of arthropod pests with which they must compete in order to produce a 

 profitable crop. Applications of chemical pesticides has been the standard 

 method of control for many years, but is now being re-evaluated in view of 

 increasing costs, environmental contamination, the development of insect and 

 mite resistance, and the disruption of natural enemy complexes. Integrated 

 pest management (IPM) programs, developed for many major agricultural crops, 

 can improve pest control efficiency by exploiting all possible means of 

 management, including cultural, biological, and chemical, resorting to the 

 latter only when nonchemical methods cannot maintain pest populations below a 

 specific economic injury level. IPM may hold potential for strawberries grown 

 in the Northeast, but alternatives and supplements to chemical pesticides are 

 presently few. 



Cultural control techniques for strawberry pests include sanitation, e.g. 

 removing dead plant material and weeds that may harbor pests, adjusting 

 planting times or patterns to avoid peak pest populations, crop rotation, trap 

 crops, and mechanical control, such as burning or flooding. Strawberry 

 production has incorporated some cultural control measures into the general 

 management scheme, such as rotation with other crops that do not share the same 

 pest complex, and renovation, during which disease-infected foliage and insect 

 overwintering sites are destroyed or tilled into the soil. The time of plowing 

 under old beds can affect the status of overwintering pests species. The use 

 of trap crops has received little attention for strawberry pests, but may offer 

 a means of reducing early outbreaks of some insects (9). Physical barriers are 

 effective against some insects, but generally have been considered too 

 expensive or labor intensive to be used (4). However, the recent introduction 

 of lightweight, synthetic row covers and application machinery may stimulate a 

 re-evaluation of this technique. Strawberry plant resistance to certain pest 

 species such as root weevils, aphids, and spider mites has been observed. To 

 date, however, this is not thought to provide economic control (1,7,10). 



Biological control refers to the use of natural parasites and predators of 

 insect pests to maintain populations below economic thresholds. This technique 

 may involve searching out and importing exotic, natural enemies, and/or using 

 conservation and augmentation techniques to increase the effectiveness of 

 natural enemies, whether native or imported (3). 



Several problems are inherent with the practical application of biological 

 control of northeastern strawberry pests. The strawberry plant is native to 

 the northeastern U.S. The wild strawberry, Fragaria virginiana , is thought to 

 be a parent of the now popular cultivated strawberry, Fragaria ananassa (2). 

 Therefore, a native pest complex exists that is both established and well 

 adapted. This situation greatly reduces the probability of finding effective 

 exotic natural enemies. In nearly every successful example of control using 

 exotic natural enemies, the pest itself was exotic. Furthermore, success with 

 exotic natural enemies usually occurs in salubrious, stable, and undisturbed 



