This document discusses two diseases that affect strawberry crops: gray mold/blossom blight/fruit rot and anthracnose/black spot. Gray mold is caused by the fungus Botrytis cinerea and leads to a velvety gray growth on fruit surfaces. It spreads through spores produced on plant debris. Anthracnose is caused by several Colletotrichum fungi and affects leaves, stems, flowers and fruit, causing dark brown or black lesions. It survives in soil for up to 9 months and spreads through splashing water and soil. Management strategies for both diseases include removing infected plant material, improving air circulation, applying protective fungicides, and rotating crops or fumigating soil to reduce
3. GREY MOULD/BLOSSOM BLIGHT/FRUIT ROT
Caused by: Bortrytis cinerea
This disease occurs on a wide range of flowers, vegetables and fruit, including strawberries.
The fungus usually produces a velvety gray growth on the surface of the fruit, but, in high
humidity, the surface growth may be cottony and white, with little or no spore production.
6. Favorable Conditions
Low temperature, high humidity and frequent rain
Survival and spread:
• The fungi over-winters on plant debris and infects flower parts, after which it either rots the
fruit or remains inactive until the fruit ripens further.
• Spores, which are produced continuously throughout the fruiting season, germinate to infect
plants
• By wind and splashing water from rain or overhead irrigation
7. MANAGEMENT
Remove and destroy all dead or infected material.
Grow fruit under plastic, use plastic mulch to reduce fruit contact with soil.
Plant in areas where wind will rapidly dry wet plants and fruit.
Plough crop debris into soil after harvest.
Protective fungicidal sprays are helpful for the control of gray mold fruit rot during periods of
moderate disease incidence such as Captan or thiram.
The proper spacing of plants and correct timing of fertilizer applications are the most important
preventive measures.
9. STAGES OF DISEASE
• Leaf spot
• Round black or light gray lesions on
leaves.
• Numerous spots may develop but
leaves do not die.
10. • Runners and petioles
• Dark brown or black sunken, circular lesions
on stems, petioles and runners
• Plants may be stunted and yellow
• Plants may wilt and collapse
• Internal tissues discolored red
Fig.:Anthracnose lesion on strawberry
runner
11. • Bud rot
• Damp, firm dark brown to black rot on
buds.
• Plants with single buds may die.
• Plants with multiple crown may wilt as
disease progresses.
• Flower blight
• Dark lesion extending down pedicel
which girdles the stem and kills the
flower; flowers dry out and die.
• Infection after pollination may result in
small, hard, deformed fruit.
12. Fruit rot
Light brown water-soaked spots on
ripening fruit which develop into firm
dark brown or black round lesions.
14. • Survival and spread:
• This is a major disease of strawberries, affecting most parts of the plant.
• It can cause serious losses throughout the season.
• Plants that are planted in infected soil become infected by splashing water and soil
• Fungus survives in soil for up to 9 months.
• Favourable conditions:
• It is favoured by warm wet weather
15. MANAGEMENT
Fumigating soil may help reduce soil inoculum.
Solarizing soil may destroy soil inoculum
Rotate to non-host crops if fumigation or solarization is not possible; wash all soil from plant
crowns prior to planting
Plant only disease free transplants
Do not use excessive amounts of nitrogen fertilizer