Dallas Morning News – March 29, 2018
PAWPAWS HAVE PROBLEMS
Pawpaw or custard apple is a nice looking small tree that produces a delicious fruit. I like it a lot. It will grow well here in north Texas – but it has a little bit of a problem that can be frustrating.
Asimina triloba
(ah-SIM- ee-ah tri-LOBE- ah) is a deciduous tree for shade or part shade. It grows to a height of 15-30’ with a spread of 15-20’. The leaves are large, somewhat floppy and have very nice yellow fall color. The purplish-green flowers in March or April are quite interesting. The delicious creamy-yellow custard tasting fruit is 3-5 inches long, shaped like a fat banana, green when young, then coppery brown when mature and edible late summer to fall.
Pawpaw is native to the eastern United States and Canada and to the deep acid soils of east Texas, but it also grows well in the black and white alkaline soils. Large spear-shaped leaves have nice yellow fall color. Young shoots and leaves covered with rusty colored down texture. Pawpaw is the largest edible fruit known to be native to America.
Pests are rare on this plant – so what’s the issue. Well- it’s very difficult to get the plant to set the wonderful fruit. Poor pollination happens in nature as well as in domestication. Pawpaw flowers are perfect, meaning they have both male and female reproductive parts, but they are not self-pollinating. The female flower stigmas mature and are no longer receptive when the male pollen is released. Also, pawpaws can’t self-pollinate. They require cross-pollination from other unrelated pawpaws.
Also, bees have no interest in pawpaw flowers so the job of pollination is left to species of flies and beetles and they are less efficient. It is possible for the home gardener to hand pollinate, using a small, soft artist’s brush to transfer pollen to stigmas. Pollen is ripe for gathering when the ball of anthers is brownish in color, loose and friable. Pollen grains should appear as small beige-colored particles on the brush hairs. The stigma is receptive when the tips of the pistils are green, glossy and sticky, and the anther ball is firm and greenish to light yellow in color. Too much trouble? I don’t – the fruit is mighty good.
Even without the fruit, pawpaw makes an excellent ornamental tree for the garden. For more information on this interesting plant see the library entry:
https://www.dirtdoctor.com/garden/Pawpaw_vq2313.htm