populations occur during harvest. Spraying during this 

 time is not recommended and growers can wait and get 

 adequate control simply with renovation when the foliage 

 is mowed off. However, for growers who feel they must 

 spray before harvest or after renovation one or two sprays 

 of kelthane or plictran may be used. Both of these 

 materials were removed from the market during 1987, but 

 some formulations of kelthane are available for use in 1988. 



Two-spotted spider mites overwinter as adults 

 and become more active as temperatures increase during 

 the summer. Dry, hot weather favors these mites. There 

 is a danger that populations can explode in a very short 

 period of time. The strawberry 1PM program is refraining 

 from making recommendations for mile control based on 

 threshold numbers, because there is little agreement 

 among researcherson what population levels are tolerable. 

 We will, however, report levels to growers. The current 

 concern is the lack of availability of milicides for those 

 growers who want to control mites. We plan to explore the 

 use of biological control of two-spotted mites with the use 

 of indigenous predacious mites (Anihlysciiis fallacis) (8). 

 This type of control can be accomplished cither by encour- 

 aging the growth of natural populations of these predators 

 or by the release of artificially-reared populations to aug- 

 ment the naturally occurring ones. In addition, the use of 

 "soft" pesticides such as insecticidal soaps, which have 

 been successful in greenhouse settings, will be evaluated 

 for efficacy in strawberries during 1988. 



normally used from bloom through harvest. 



In Ontario, grey mold has been shown to overwin- 

 ter in the green leaf tissue under the winter mulch (2). This 

 fact, if it is also true in New England, has significant 

 implications for disease management. According to the 

 Ontario work, spores from infected crop residues land on 

 newly formed and expanding leaves in the fall. The spores 

 germinate and invade the leaf tissue and then enter a 

 quiescent state for the winter protected by the winter 

 mulch. At that time there are no visible symptoms of 

 infection. Then, in the spring when these leaves begin to 

 sencsce and die, the fungus grows and produces new spores 

 which are available to infect the tender blossom petals, 

 which then infect the fruit. Using this information, one can 

 protect the leaves from infection in the fall or knock back 

 the initial inoculum in the spring before the blossoms 

 appear. This treatment eliminates the need for numerous 

 sprays, and the potential for any fungicide residues on the 

 fruit. Since no developing fruit will be present at the time 

 of sprays, they cannot accumulate fungicide (13). Leaf 

 protection can be accomplished by applying fungicides to 

 the surface or by providing competitive organisms which 

 will inhibit the ability of the fungus to germinate or pene- 

 trate the surface of the leaf tissue (5). Two yeast species and 

 one bacterial species which occur naturally on the surface 

 of strawberry leaves and provide effective biological con- 

 trol of grey mold in Ontario have been identified (13). The 

 Strawberry IPM program is determining the efficacy of 

 these methods in Ma.ssachusetts. 



Key Disease Organisms and Their Damage 



Grey mold (Botrylis cinerea). This fruit rot is, by 

 far, the problem of most concern to Massachusetts growers 

 in terms of potential for yield reduction (12). The Botrytis 

 fungus infects the Hower petals or sepals and then prolifer- 

 ates in the developing fruit causing it to rot. The berries 

 may rot on the plant or shortly after they have been 

 harvested. Grey mold can cause very heavy losses in years 

 with damp wet weather in the spring, especially if it occurs 

 during bloom. If not managed, under these conditions a 

 nearly complete crop loss is possible. Even under a 

 fungicide spray program a significant yield reduction may 

 occur. Current practices include 1 to 12 sprays per season 

 with captan, benlate, captan/benlate, or ronilan. 



During 1987 an IPM spray regime consisting of 3 

 bloom sprays of captan or ronilan was compared with a 

 typical spray regime. We found no significant difference in 

 the amount of berry rot found with either regime (12). 

 These results concur with work done by other researchers 

 (3) and suggest that 3 well-timed bloom sprays are as 

 effective for grey mold control as the 4 or more sprays 



Grey mold management presents a major chal- 

 lenge to pesticide reduction strategies. We are targeting a 

 reduction in the number of sprays, adjusting spray timing 

 to early season, and exploring the potential for biological 

 alternatives to reduce the pesticide load on the environ- 

 ment. Our approach is especially timely since captan's 

 registration is under special review and grey mold has 

 developed resistance to benlate and ronilan in some areas. 

 Furthermore, benlate has been shown to adversely affect 

 populations of predacious mites in apples and may do the 

 same in strawberries. 



Black root rot is a complex of organisms which 

 results in the decay and blackening of the perennial and 

 feeder roots. The causal fungus, RItizoctonia fragariae 

 (Ceratobasidium sp.), commonly is associated with straw- 

 berry roots. R.fragariac invades strawberry roots by direct 

 penetration, causing cortical decay and rootlet death. This 

 injury results in reduced plant vigor, and degeneration and 

 premature death of plants. 



Black root rot is difficult to manage with existing 

 measures. In Massachusetts, we suggest planting in well- 



