Integrated Pest Management for 

 Commercial Strawberry Growers 

 In Massachusetts 



Sonia G. Schloemann and Daniel R. Cooley 



Department of Plant Pathology, University of Massachusetts 



The strawberry IPM program began in 1987 with 4 

 cooperating growers. This number expanded to 14 in 

 1988. This e.xpansion provided a better sample of 

 grower practices and improved overall contact with 

 Massachusetts growers. We also expanded the geo- 

 graphic base of the progi'am to include a wider area of 

 the state. Cooperating growers were chosen from 

 among those who had responded positively to a ques- 

 tion on the 1 987 gi'ower survey asking if they would like 

 to become involved in the IPM program. 



Fieldswere scouted for tarnished plant bug, straw- 

 beny bud weevil (clipper), and two-spotted mite. 

 Recommendations were also made for Botiytis gray 

 mold management. The sampling methods used for 

 monitoring insect populations were those generally 

 used by other IPM programs in New York and New 

 England. Relative yield impact due to pest injuiy was 

 monitored and comparisons were made between areas 

 under IPM management and ones under conventional 

 management. 



Tarnished Plant Bug 



For this insect, two scouting methods were com- 

 bined. It has been asserted that the immature stages 

 are the form of this insect that cause economic injury to 

 strawberries (Schaefers, 1980). Adults are present, 

 but in lesser numbers than nymphs, and are consid- 

 ered less of a threat. Nymphs are said to hatch around 

 bloom, the gi-owth stage most susceptible to TPB in- 

 juiy. White sticky traps were used for an indication of 

 adult activity (Coli, 1985). Thresholds are not available 

 for this method, because trap catches do not correlate 

 with resulting injury levels. However, traps can deter- 

 mine when adult tarnished plant bugs become active. 

 We are developing a database of trap catches over 

 several years to be used to develope thresholds. The 

 main sampling method used for making management 

 recommendations has been to assess nymph popula- 

 tions. This sampling is done by shaking flower trusses 

 and counting the number of nymphs that fall out. A 

 threshold number of 1 nymph per 25 flower trusses 

 was developed in New York (Schaefers, 1980) and has 



been used by our program for two years. Additional 

 information suggests that the threshold perhaps can be 

 raised substantially to 1 nymph per flower truss 

 (Mailloux and Bostanian, 1988). 



The situation is somewhat confounded by reports 

 that suggest that both nymphs and adults are causing 

 economic injuiy to strawberries in Massachusetts. 

 Adult insects cause much damage to strawberiy pro- 

 duction in Maine and New Hampshire, but are consid- 

 ered to be of little consequence in New York. New York 

 researchers consider nymphs to be the primaiy prob- 

 lem. Massachusetts may be at the inteiface of two 

 ecological regions, which suggests the need for further 

 research. 



Among our cooperating growers the average 

 number of insecticide applications for tarnished plant 

 bug control in 1987 was 1.8 sprays per season. Under 

 IPM practices, these same growers made 0.9 insecticide 

 applications in 1988, a 50 % savings. This level can also 

 be compared to non-IPM areas on the same farms this 

 year where 1.4 insecticide applications were made. 

 Here, IPM recommendations resulted in a 35% savings 

 (Schloemann and Cooley, 1988). No significant differ- 

 ences in injuiy to fruit were obsei-ved. 



Strawberry Bud Weevil 



Strawberry bud weevil is an insect which destroys 

 individual buds before the strawberries can form. This 

 pest is of gi'eat consequence in mid-western states and 

 is becoming of greater concern in New England. Of the 

 14 cooperating growers in 1988, 11 sampled positive for 

 the presence of strawberiy bud weevil (clipper). Only 

 4 of these gi-owers had levels of clipper high enough for 

 concern, though 8 typically spray for them. The sam- 

 pling method for clipper involved counting the number 

 of clipped buds per foot of row. A threshold of 0.6 

 clipped buds per foot was used (Schaefers, 1972). The 

 problem with this method is that it evaluates damage 

 after the fact. Work has begun in New York to evaluate 

 the efficacy of boll weevil traps for clipper. This trap- 

 ping may be a valuable innovation for the future. 



Fruit Notes, Spring, 1989 



13 



