The Online Gardener's Handbook 2010
Chapter 5: Fruit
Raspberry, Blackberry

Table of Contents

  1. Introduction
  2. Anthracnose
  3. Aphids
  4. Cane Borer Beetles
  5. Raspberry Crown Borers
  6. Fruitworms
  7. Fruit Rot
  8. Powdery Mildew
  9. Rust Diseases
  10. Raspberry Sawflies
  11. Sap Beetles
  12. Spur Blight
  13. Viruses
  14. Learn More

Introduction

In this chapter, a description of various raspberry pests will be provided along with suggested management options. These management options will not include the use of pesticides. Some biopesticides and certain reduced risk pesticides are still available to the homeowner for controlling weeds and pests in lawns and gardens. For more information, refer to Chapter 2 of this handbook and the Ministry of the Environment's website. For suggestions on managing specific weeds and pests, consult local horticulturalists, Master Gardeners or your local garden supply centre.

Anthracnose

Anthracnose mainly affects canes, causing numerous grey spots with purple borders. Bark may crack during winter and canes will dry out and break readily during fruiting. If severe, it can affect branches, fruit stems and leaves. Immature fruit may turn brown and dry up, while ripe berries become soft and misshapen.

Management Options

Promote air circulation. Cut old canes and severely affected young canes at ground level as soon as harvest is completed. Thin remaining canes to 15 cm apart and the row to no wider than 30-50 cm. Destroy all cut canes. Keep rows free from weeds.

Aphids

Aphids are soft-bodied, greenish to brown, 5mm, pear-shaped insects. They sometimes infest raspberry plants. For more information, refer to the Aphids section in Chapter 1.

Management Options

Small numbers of aphids can be removed or crushed by hand when they are discovered. Small, localized populations on leaves or stems can be pruned off - dispose of infested parts as you cut them in a bucket of soapy water. You will need to check plants frequently, as isolated aphids are easy to miss and populations can increase rapidly. For sturdier plants, a hard spray of water directed at the infested shoots can also wash away aphids. Do this earlier in the day so plants can dry off and do not become susceptible to disease. Do not overfertilize plants, as aphid outbreaks tend to be worse when nitrogen levels are high. Remove any weedy plants in and around your garden that may be harbouring aphids. Aphids are highly susceptible to a number of predators, parasites and fungal diseases. You will know parasites are at work in your garden if you see swollen, golden brown, papery aphids on your plants - these are mummies and contain the pupating parasite. Aphids infected with fungal diseases may change colour will appear fuzzy, shrivelled or covered in whitish strands. Promote the activity of these natural enemies by minimizing the use of pesticides in and around your garden, and by planting nectar-producing flowers nearby.

Cane Borer Beetles

In June and July, cane borer beetles fly from wild or neglected raspberries or roses to attack cultivated raspberries. The female is a black and yellow long-horned beetle with two black dots on a yellow thorax. It cuts a double row of punctures about 1.25 cm apart around the raspberry stem near the tip and lays an egg between the girdles. The tip wilts and the larva bores down into the cane about 5 cm where it hibernates. The following season it continues downward and pupates. The cane dies.

Management Options

Cut out and destroy wilting tips as soon as they appear. Make the cut about 15 cm below the girdles. Cut out wilted or dead fruiting canes. Destroy wild and neglected raspberries in the immediate vicinity.

Raspberry Crown Borers

Raspberry crown borers are 2.5 cm long, cream-coloured larvae with brown heads. They burrow at the base of the cane, in larger roots and crown. Affected canes wither and die, or growth is limited and fruit is small. The adult is a clear-winged moth with a wingspan of 2.5-3.0 cm. The yellow bands across its black abdomen make it resemble a yellow jacket wasp.

Management Options

If boring is seen above ground, probe the holes with a sharp knife to kill larvae. Remove more severe infestations in late September to early October after all the eggs have been laid. Burn affected canes, including large roots, and plow under the soil. Remove any neighbouring wild raspberry canes.

Fruitworms

The 4 mm brown fruitworm beetles skeletonize young unfolding leaves, destroy blossom clusters and eat holes in buds. Small 6 mm larvae feed inside buds and developing fruit.

Management Options

Till the soil in late summer or early fall to expose pupae to natural enemies. Hand pick adult beetles and dispose of in a bucket of soapy water.

Fruit Rot

Fruit rot may be a problem if rainy weather prevails between blossoming and harvest. Dark grey, black or olive-green moulds occur particularly on ripe berries.

Management Options

Do not space plants too closely to allow for adequate air circulation. Avoid overhead watering and water in the morning to allow time for plants to fully dry. Harvest fruit immediately after ripening. Remove and destroy any moldy fruit.

Powdery Mildew

Powdery mildew may occur during hot, humid weather. It appears as a white, powdery fungal growth on leaves at the tips of new shoots and on the berries. It causes stunting of young canes and distortion of leaves.

Management Options

Reduce shading and improve air circulation around the planting. Prune to keep rows narrow (30 - 50 cm) and canes spaced 15 cm apart.

Rust Diseases

Three rust diseases commonly affect raspberries and blackberries: yellow rust and late yellow rust occur on red raspberries; late yellow rust affects purple raspberries; and orange rust occurs on blackberries.

There are many symptoms of yellow rust and late yellow rust. Clumps of orange-yellow spores develop on the undersurface of leaves and occasionally on the fruit; leaves turn yellow, develop brown areas, and may drop prematurely. Severe premature leaf drop will predispose canes to winter injury. Yellow rust can also infect canes, causing overwintering lesions to become cankerous, and fruiting canes to break or dry the following summer. Yellow rust and late yellow rust fungi overwinter in infected tissues.

Blackberries infected with orange rust develop upright, spindly shoots. In the spring, a yellow coating develops on the undersurface of developing leaves, leaving them dwarfed and misshapen. This coating later breaks open to reveal bright orange spores, which spread the disease.

Management Options

Orange rust overwinters in the canes, crowns and roots of diseased plants. Diseased plants do not recover and should be dug up and removed when noticed.Yellow rust and late yellow rust are of minor importance in Ontario, causing problems only in years with late spring rains and cool, humid weather. Remove and discard infected canes and leaves in fall or early spring to reduce the spread of the disease.

Raspberry Sawflies

Larvae of raspberry sawflies are pale green and about 1 cm long when full grown. Their damage can be seen by late May or early June. Large irregular holes appear in leaves and all but the larger veins of the leaf can be destroyed. The damage is usually not harmful.

Management Options

Healthy vigorous plants can tolerate sawfly damage unless populations are extremely high. Control measures are usually not needed.

Sap Beetles

Sap beetles, also called picnic beetles, are 6 mm long and black with cream markings. They attack raspberries, tomatoes and sweet corn. They bore into berries when almost ripe, and may also invade picked berries. Large numbers make them very difficult to remove by hand.

Management Options

Remove picked fruit from the planting promptly. Use bait of mashed bananas, ripe melon, or chopped immature sweet corn placed in open containers in several places between plantings; renew regularly and destroy the beetles that have been trapped. Apple cider vinegar or a mixture of yeast, sugar and water combined with a few drops of liquid detergent will drown the beetles.

Spur Blight

Spur blight is most serious on the lower part of first-year canes where purplish-brown areas appear around joints of leaf stems and canes. On second-year canes, diseased areas are grey with small black pimples. Canes are weakened and may be killed during winter. Buds in affected areas produce weak branches and the leaves turn yellow and brown when berries are ripening.

Management Options

Promote air circulation. Cut old canes and severely affected young canes at ground level as soon as harvest is completed. Thin remaining canes to about 15 cm apart and the row no wider than 30-50 cm. Destroy all cut canes. Keep rows free from weeds.

Viruses

Viruses cause poor plant vigour, low yields, short-lived plantings and crumbly berries. Leaves may be mottled, puckered and curled. Affected plants are most visible in June. Most viruses of raspberries are spread by aphids.

Management Options

Spray water with force to wash aphids from developing new growth. Remove and destroy all infected plants. Replant with culture-indexed stock.

Learn More

 


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 25 July 2005
Last Reviewed: 28 June 2010