The Online Gardener's Handbook
Chapter 5: Fruit
Blueberry, Currant, Gooseberry
Table of Contents
- Currant and Gooseberry
- Learn More
In this chapter, a description of various berry 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.
Eggs of this pest are laid in small green fruit, and the larvae that emerge from them feed on the developing fruit. One larvae ties clusters of several fruit together with silk and damages many berries. Messy feeding sites, with external sawdust-like excrement and webbing, are characteristic of the damaged fruit. The caterpillar is greenish, with brownish red tinges on the back and about 9.5 mm long when mature. Adults are V-shaped with a pointed head, and are greyish-brown with white markings.
Handpick and dispose of larvae. Keep blueberry bushes free of debris. Frequent cultivation of the soil between plants can help keep numbers of this pest down.
Phomopsis and Fusicoccum Stem Cankers
Several stem cankers affect highbush blueberries. Fusicoccum forms distinct elliptical cankers on the lower half of the stem. Phomopsis cankers are less defined than fusicoccum, and appear as flattened and elongated areas on the stem. Both cankers can result in rapid wilting and dying of the two to three year old blueberry canes. Leaves turn reddish brown and remain attached to the cane.
Prune out and burn diseased canes as soon as they appear. Blueberry plants are more susceptible to phomopsis if they are over-fertilized with nitrogen, are grown in poorly drained soils, suffer from winter injury or are damaged or wounded.
Currant and Gooseberry
Aphids are often a serious problem on currants, especially red currants. They cause leaves to pucker, curl and show red blisters.
For more information, refer to the aphids section of Chapter 1.
For management options, see Raspberries.
Currant Borers, Currant Stem Girdlers
Currant borers and currant stem girdlers cause injury to the wood of the canes. Affected shoots look sickly with small, yellowed leaves. Eventually, the shoots will die.
Shoots should be cut out and destroyed when symptoms are noticed at any time of the year. Shoots older than three years are less productive and should be removed in spring before leaf buds break to minimize the potential for attack. Apply manure to promote vigorous growth of new canes.
Currant Fruit Flies
Maggots in the fruit are larvae of currant fruit flies. Infested berries ripen prematurely and many drop to the ground.
Remove and destroy infested berries to reduce risk the following season.
The larva of the sawfly is 2.5 cm long, green, with many legs and a black spotted body. It eats the leaves of gooseberries and red or white currants (not black currants) as plants come into full leaf. The adult is a small black wasp-like insect.
Inspect plants regularly beginning in the spring and remove any larvae by hand.
Fungal leaf spot diseases are often the cause of early defoliation. Spots are first brown and later grey; leaves yellow and drop.
Gathering and destroying infected leaves after they have dropped can be a very effective sanitation method if done thoroughly. If mulch is used, apply fresh mulch after leaf fall.
Powdery mildew is a problem mainly on gooseberry and black currant. The fungus initially appears as a white fluffy mildew that later turns to a brown, felt-like coating on leaves, twigs, and fruits. Hot, humid weather favours the disease.
Reduce shading and improve air circulation around the planting. Prune to keep rows narrow (30 - 50 cm) and plants spaced 15 cm apart.
The rust fungus spends part of its life cycle on white pine, but requires the currant or gooseberry as a host to complete its life cycle. Only the black currant, however, is defoliated. Orange spots, later growing into pimples, appear on the lower surface of leaves.
The Consort black currant is resistant to white pine blister rust. Avoid planting currants and white pine near each other.
Scale insects, particularly San Jose scale, are often found on shoots. The scales are up to 4 mm across, round, with a greyish, nipple-shaped projection in the centre that contain lemon-yellow, sack-like insects. For more information, refer to the section on scale insects in Chapter 1.
A light infestation may be kept in check by birds and beneficial
insects. Scale biological controls are commercially available, and
may help to reduce populations.
For more information:
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