17 



A few years ago, experience in developing and publishing the New England 

 Guide for Managing Diseases and Insects of Small Fruits (3) showed that there 

 was not a great deal of current knowledge on strawberry pest control. However, 

 a recent survey (5) has identified the most important pathogens. Several fungi 

 contributed to berry rots, and several other fungi contributed to root rots. 

 The most significant fruit pathogens (and the diseases they cause) were 

 Botrytis cinerea (grey mold), Phytophthora cactorum (leather rot), Haines ia 

 lytheri (tan brown rot), and Phomopsis obscurans (berry blight). The etiology 

 of each of these pathogens is distinct, but in general wet weather and 

 increasing fruit maturity cause more disease development. In unmanaged 

 situations, fruit rots can destroy the entire crop. Even using recommended 

 controls, adverse conditions can cause significant crop loss. For example, 

 gray mold causes between 20% and 60% loss in Quebec, depending on weather (4). 

 Leather rot losses in Ohio approached 40% in commercial beds in 1980 and 1981 

 (6). Gray mold is endemic in strawberry fruit, and Botrytis was frequently 

 isolated from all beds in the Massachusetts survey. Leather rot was also 

 frequently observed. 



The most damaging strawberry insect and weed pests in Massachusetts have 

 not been determined. According to growers, the most important insect pests are 

 tarnished plant bug ( Lygus lineolaris ), strawberry bud weevil or clipper 

 ( Anthonomus signatus ), white grubs ( Phyllophaga spp.), and strawberry root 

 weevil ( Otiorhyncus ovatus ). There is little doubt that tarnished plant bug is 

 the major contributor to misshapen strawberries (8). 



Several weeds cause economic problems in strawberries, including several 

 grass species, Galinsoga, and thistle. Though growers cite these as the 

 problem weeds, it is not clear whether this is the case, and if so, how much 

 damage is caused. However, it is clear that weeds are a major factor causing 

 beds to be taken out of production. 



Previous work supplies some tools to start an IPM program. Gray mold 

 epidemiology is partially understood. One study has shown that floral and 

 pedicel infections early in the season are more important to future berry 

 infections than direct infections occurring at or near harvest (7). A few 

 applications of a fungicide early in the season may be as effective as a series 

 of applications from bloom through harvest. Such applications could be made 

 more efficient by applying epidemiological data from Quebec which indicate that 

 temperatures from 15 to 20°C and relative humidities from 90 to 100% for at 

 least 28 hrs . are optimal for gray mold epidemics (4). An experimental model 

 for gray mold pressure is in the process of being published (1). A similar 

 model of temperature and moisture effects on leather rot infection has been 

 published recently (6). 



Another element in a fruit rot control program would involve studying 

 fungicide retention and redistribution. Presently, growers often apply 

 fungicides every 3 to 5 days around harvest if weather is wet, on the 

 assumption that this will increase protection against berry rots. On apples, 

 captan remains effective for 1 week regardless of rain (9). Frequent 

 applications of fungicide around strawberry harvest may be useless. 



Insect monitoring would be a key element in the program. Initial work 

 indicates that tarnished plant bug traps similar to those used in apple IPM (2) 

 could be successful in strawberry. One technique, using non-visual traps, has 



