3.30 per kg (0.50-1.50/lb) in 1989.) Operating costs are unknown but should be relatively low; pawpaws require low levels of inputs, having excellent pest resistance and good drought tolerance5.

The major components of pawpaw yield are probably tree vigor, blossom density, and fruit set. Fruit set in pawpaw is determined primarily by pollination success, which depends on successful insect pollinator activity, pollen compatibility, and the normal development of the fruit (i.e., the absence of abortion). Of the components of fruit set, the problems of low yields are almost entirely related to the insufficient availability and abundance of pollinators (Willson and Schemske, 1980; Lagrange and Tramer, 1985) and to unsuccessful pollinations and/or fertilizations caused by pollen-incompatibility (Zimmerman, 1940; McDaniel, 1958). The low yields of the Annonas are likewise related to low rates of natural pollination, and in commercial practice are solved by hand-pollination (Thakur, 1965; Farooqi et al., 1970). Even in Israel, where labor is expensive, hand pollination is sometimes resorted to (Gazit et al., 1982).

Inadequate pollination can result from problems of the biology and ecology of the pollinators. Flies (Muscidae and Sarcophagidae) and beetles are believed to be the primary pollinators (Pammel, 1903; Kral, 1960; Davis, 1974; Willson and Schemske, 1980). Low levels of pollinator activity may be caused by inclement weather, predator interference, low nectar production, or the unattractiveness of the flowers. This area has not been studied. Nothing is known about the abnormalities that may occur in the course of embryo, seed, and fruit development in pawpaw that may cause fruit to abort. In the orchard setting at Wye, Maryland, U.S.A., pollination has not been a problem, fruit set has been abundant, and fruit abortion has been common (10-20%) in the first month. In the wild, where large groves may be composed of a single or a few clones, pollen-incompatibility can be a primary source of low yields. The pawpaw is an obligate outcrossing species, although there are occasional reports of self-compatible clones (Davis, 1974; Robinson, 1974).

Maintaining quality in the process of harvest is a problem, because pawpaws are soft and easily bruised. Fruits are difficult to see beneath the dense foliage, and being green in color are easily missed. Color change does not signal ripening of the fruit; ripeness is judged by softness and aroma. Because pawpaw trees normally grow 5 to 7 m high, some device will be required for picking higher fruits, but ladders seem unsuitable because of the weakness and flexibility of the tree.

Judging from the comments of many who have tried fresh pawpaw, the quantity of

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