LOCALLY ESTABLISHED BOTRYTIS FRUIT ROT OF MYRICA-FAYA, A NOXIOUS WEED IN HAWAII

Faya (Myrica faya) is an introduced weedy tree threatening native ecosystems in Hawaii. Classical biological control has been investigated for several years but has yielded few insect pests or pathogens, none of which currently offers control in the field. As an alternative, attention was recently given to identify locally established insect pests and pathogens. Botrytis cinerea causes widespread fruit rot and is the first pathogen reported from faya in its nonnative habitat. Infection of flowers and foliage is rarely observed. Fruit rot occurs on trees of all sizes in a variety of habitats throughout the Hawaiian range of faya. In 1992, over 49 and 51% of mature fruit at two sites were infected. Similar percentages of immature fruit were infected or infested with B. cinerea. Adults and fruit-feeding larvae of Amorbia emigratella and Cryptoblabes gnidiella collected from infected fruit clusters in the field were heavily infested with viable conidia and may serve as vectors. Selection of more aggressive or ecologically fit strains or introduction of large numbers of Botrytis-infested insect vectors early in the fruiting season may enhance faya biocontrol.