The Online Gardener's Handbook 2010
Chapter 5: Fruit

Table of Contents

  1. Introduction
  2. Black Root Rot
  3. Fruit Rot or Grey Mould
  4. Leaf Spot
  5. Plant Bugs
  6. Red Stele
  7. Slugs
  8. Spittlebugs
  9. Strawberry Clipper Weevils
  10. Strawberry Leafrollers
  11. White Grubs and Wireworms
  12. Learn More


In this chapter, a description of various strawberry 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.

Black Root Rot

Black root rot is a soil borne fungal disease causing roots of old plants to turn dark brown with no feeder roots present. The outer root covering peels off easily. Above ground portions of the plant will be less vigorous and may die.

Management Options

Avoid heavy, poorly drained soils with high water tables to prevent roots from becoming waterlogged or frozen. Use certified plants to reduce the risk of introducing root diseases and viruses into the garden. Before planting, check plants to ensure the roots are healthy and cream coloured.

Fruit Rot or Grey Mould

Fruit rot, also called grey mould, is common during wet weather between blossoming and harvest. Berries rot when almost ripe, although green fruit may also be infected. Control is difficult when disease is established; prevention is more effective.

Management Options

Protect blossoms from frost injury with straw mulch. Remove infected berries from fruit clusters when observed. If irrigation is necessary, water thoroughly in the morning to allow time to dry before evening. Pick all fruit at the end of harvest to reduce the incidence the following year.

Leaf Spot

Leaf spot is a fungal disease that causes red-purple spots on leaves of first- and second-year plants. Spots enlarge and centres become grey. If spots are numerous, leaves may be killed and yield reduced.

Trim off diseased leaves when planting. Choose resistant varieties, if available. Plant in well drained soil in a sunny area with good air circulation.

Plant Bugs

Plant bugs pierce flower clusters and developing fruit, sucking the sap and causing small deformed berries. For more information, refer to the Plant Bug section in Insects and Diseases Attacking Many Vegetables.

Red Stele

Red Stele is a common root rot fungal disease that causes the inner roots to turn rusty red in April-May and September-October and have a rat-tailed appearance. Plants are stunted because roots function poorly and berries are small though not deformed.

Management Options

Where this disease is a problem, obtain certified young plants with cream-coloured roots every year and harvest during the following year only. Inspect plants closely and do not plant if roots exhibit any symptoms. Since this is primarily a disease of older plants, remove old plantings after harvest. Improve soil drainage and avoid soil compaction. Rotate plants among different locations, where space permits. Plant resistant varieties, where available.


Slugs create small to moderate holes in fruit and leaves. For more information and management options refer to the slugs sections of Chapter 1 and Chapter 5.


Spittlebugs are small, sap-sucking insects. In their immature stages, they cover themselves with a frothy saliva-like protective mass. The adults are brown and inconspicuous, and they jump easily when disturbed. Stunting and distorting of the new growth are the most common signs of damage. They are present in May and early June with usually one generation per season.

Management Options

Pick off and destroy. Spittlebugs can be washed off plants with a strong jet of water.

Strawberry Clipper Weevils

Strawberry clipper weevils are destructive, 2-3 mm long, reddish-brown beetles with long snouts. Adult weevils poke holes and lay eggs in strawberry buds and partially cut the stems below the buds, causing them to wilt and drop off or to hang by a thread.

Management Options

Remove and destroy any fallen stems, or those that are hanging by a thread, as these may contain weevil eggs.

Strawberry Leafrollers

Strawberry leafrollers are small, greenish or bronze 1.25 cm long caterpillars that fold or roll leaflets with fine silken threads. Overwintering as pupae, small greyish or brown moths emerge in mid-to-late May to lay eggs on the undersurface of the leaves. The larvae migrate to the upper leaf surface when half-grown, roll the leaves for protection and continue feeding. A second generation occurs in mid-August.

Management Options

If infection is minor, remove affected leaves and destroy. Natural enemies are often present and help keep populations in check.

White Grubs and Wireworms

Wireworms and grubs may cause extensive damage to new strawberry plantings as the larvae feed on the roots. Usually plants collapse during the fruit-sizing period. They are often present in new gardens when sod is converted to garden. For more information refer to the Soil Pests section of Chapter 1.

Management Options

For management options, refer to the White Grubs section of Chapter 5.

Learn More

For more information:
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