Raspberries, which naturally contain vitamins A and C, have a distinct flavor and shape that makes them easy to identify. The berries are used in everything from yogurt to fruit drinks. Raspberries may be eaten fresh, frozen or cooked. Any black substance on raspberries is a bad sign that may make them inedible.
Proper raspberry care prevents the pests and diseases. Plant raspberries in well-drained soil. Standing water encourages fungal growth. Manage weeds that appear either with herbicide or by hand. Thin the raspberry plant out every year, pruning canes and dead growth. Always dispose of old canes. Do not place them in the compost pile or make them into mulch. Diseases and pests may linger on dead canes and branches.
Many fungal problems create black spots and growths on raspberries. Anthracnose begins with dark, reddish-purple spots that are oval. Later, these spots turn gray and purple. Dark purple-brown spots, almost black in color, may appear on the leaves. Anthracnose causes canes, leaves, flowers and fruit to die. Cane blight is a spore-borne disease that generally begins in the canes. Black, gray and brown lesions appear on the canes, weakening them and causing breakage. Canes, branches and buds die if cane blight is not treated. Fireblight is a bacterial disease that kills raspberry fruits and shoots. Canes turn dark green in early stages of fireblight, but later become black and distorted.
Raspberry cane maggots are smaller than the standard housefly but seriously damage. The maggots damage canes, making them turn purple or black where they burrow inside. Sap beetles, also known as picnic beetles, are black insects that eat raspberry fruits. They may be seen with the naked eye, often grouping up on raspberries as they feed.
Treat fungal problems and bacterial diseases with fungicide. Use copper- or sulfur-based fungicide to treat raspberries regularly once a year as a preventative measure. Treat pests with pesticide and keep plants pruned and weed free to prevent pest infestations. As soon as signs of damage become apparent, prune all parts damaged by pests or diseases and discard them immediately.