Strawberry

Table of Contents

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

Black Root Rot

Black root rot is a soil borne disease causing roots of old plants to turn dark brown with no feeder roots present. The outer root covering peels off easily.

Treatment

Cultural control: 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.

Chemical control: None are known at this time.

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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.

Treatment

Cultural control: 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.

Chemical control: Start spraying just before first blossoms open, and repeat as indicated on the product label. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Leaf Spot

Leaf spot disease 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.

Treatment

Cultural control: Trim off diseased leaves when planting.

Chemical control: Spray one month after planting and repeat as indicated on the product label. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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Plant Bugs

Plant bugs pierce flower clusters and developing fruit, sucking the sap and causing small deformed berries. Adult tarnished plant bugs (TPB) are brown, while the four-lined plant bugs (FLPB) are greenish-yellow with four black stripes. Both are triangular in front, 6-7 mm long and about half as wide. They are very active, readily flying when disturbed. Young TPB are light green, while young FLPB are bright red, each with dark spots and markings. The TPB can be a problem throughout the season, while FLPB is prevalent in late spring and summer.

Treatment

Cultural control: Follow proper garden sanitation practices in fall and spring.

Chemical control: If there has been a problem in the past, spray just before blossoms open and repeat as indicated on the product label. If many blossoms have opened, spray during late evening to avoid killing bees.

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Red Stele

Red Stele is a common root rot disease causing 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.

Treatment

Cultural control: Where this disease is a problem, obtain certified young plants with cream-coloured roots every year and harvest during the following year only. Since this is primarily a disease of older plants, remove old plantings after harvest. Improve soil drainage and avoid soil compaction. Plant in a different location where space permits.

Chemical control: There are none known at this time.

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Slugs

Slugs are teardrop shaped, slimy and legless and create small to moderate holes in fruit and leaves, leaving telltale glistening trails. Damp rainy weather and mulches favour slugs.

Treatment

Cultural control: Remove materials that would provide daytime hiding sites such as plant debris, rocks, boards and logs. Promote air movement by thinning plants. Place shallow dishes of beer or juice as bait and replace frequently. Set out traps of 15 cm square boards and handpick slugs from the boards.

Chemical control: When injury is noticed, place bait in small amounts on soil at 1 m intervals; cover with boards or bricks. Keep bait moist. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

Caution: Bait is attractive and very poisonous to dogs and birds. Do not apply bait on edible parts of plants.

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Spittlebugs

Spittlebugs are 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.

Treatment

Cultural control: Pick off and destroy.

Chemical control: There are none known at this time.

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Strawberry Clipper Weevils

Strawberry clipper weevils are destructive, 2-3 mm long beetles with reddish snouts. They cut the stems of blossom buds, causing them to wilt and drop off or to hang by a thread. Observe strawberry buds closely, and spray when first clipped buds are noticed.

Treatment

Cultural control: None

Chemical control: If many blossoms have opened, spray in the evening to avoid killing bees. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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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.

Treatment

Cultural control: If infection is minor, remove affected leaves and destroy.

Chemical control: If past damage has been severe, apply insecticide using sufficient water to thoroughly wet plants during the first or second week of June and repeat as indicated on the product label. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

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White Grubs and Wireworms

White grubs are young June beetle or Japanese beetle, or European chafer. They are plump, white larvae with brown heads. Wireworms are orange, hard-bodied larvae with six legs. They both 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.

Treatment

Cultural control: If the area to be planted is in grass sod, till or dig the soil before mid-May and delay planting until the following year. During the fallow year, cultivate the area regularly, or plant the area with a crucifer crop (cabbage, broccoli, cauliflower, kale, Brussels sprouts, kohlrabi) or snap beans, as roots of these plants are not favoured by white grubs or wireworms.

Chemical control: None are known at this time.

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Related Links

• Berries
• Diseases
• Insects
• Master Gardeners
• Landscape Ontario

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