BIOLOGICAL CONTROL IN THE PHYLLOSPHERE

This article considers biological control in the leaf-surface habitat within a broad ecological context, with emphasis on plant-microbe interactions. The form of biocontrol discussed is microbial antagonism by epiphytes or en­ dophytes. Thus, for the sake of some focus, I do not consider mechanisms such as induced resistance, cross protection, and related phenomena, despite their importance and potential for disease control. I interpret the phyllosphere loosely and include examples from other similar aerial habitats such as the anthoplane (floral surfaces; 96). This article should be viewed against the wealth of literature on biocontrol in general and on the microbiology of leaf surfaces (II, 20, 55, 75, 148) in particular (Figure 1). Biocontrol specifically in the phyllosphere (or aspects of the topic) has been extensively reviewed since 1980 (6,22,25,26,48,62, 72, 104, 168 , 176). Elner & Vadas comment that "A high ratio of review to research papers on a particular topic should be regarded as indicative of data starvation and, perhaps, an unconscious need to perpetuate a set of paradigms by repetition" (65, p. 121). As we have reached that point in biocontrol , why another review? Rather than a conventional review, I try here mainly to synthesize information from diverse fields and to draw analogies with other ecological systems, which I hope prove useful in developing general princi­ ples and plotting future directions.