1 Leaf spot

: Mycosphaerella fragariae

2 Fruit rot

: Botrytis cinerea

1. Common Leaf spot
: Mycosphaerella fragariae
Class : Dothideomycetes
Order : Capnodiales
Family : Mycosphaerellaceae
Synonames: Ramularia leaf spot, Strawberry leaf spot,
Bird’s-eye spot, Gray spotness, and White spot

Economic importance:
Leaf spot is one of the most common diseases of
strawberries, occurring worldwide in most cultivars.

 Initially, small, deep purple, round to irregularly
shaped spots appear on the upper leaf surface
 These enlarge to between 3–6 mm in diameter. They
retain a dark red margin, but the centers turn brown,
then grey and finally white. Spots may join and kill
the leaf
 The fungi also attacks the petioles, stolons, fruit stalks
and fruit as shallow black spots.

Symptoms: Fruit:
 Superficial black spots (6 mm in diameter) form on ripe
berries under moist conditions.
 These spots surround groups of seeds (achenes) on the fruit
surface. The surrounding tissue becomes brownish black, hard
and leathery. The pulp beneath the infected area also becomes
discolored, however, no general decay of the infected berry
occurs. Usually only 1-2 spots occur on a berry but some may
have as many as 8-10 “black-seed”. Symptoms are most
conspicuous on white, unripe fruit and on ripe fruit of light
colored cultivars. Economic losses in this case are due to
unattractiveness of “black seed” spots on fruit, rather than
fruit rot.

Favourable condition:
 Extended wet periods, particularly in late spring

Disease cycle:
• infected leaves from current and previous strawberry
• Splashing water from rain and overhead irrigation

Spores (conidia), are produced in small dark fruiting bodies (pseudothecia)
within leaf lesions, and serve as inoculum. In this instance infection is a
continuous process with older lesions producing conidia to infect young
leaves during each season. Conidia landing on leaf surfaces produce germ
tubes which penetrate through natural leaf openings (stomata) on upper and
lower surfaces of leaves.
New conidia are produced on clusters (fascicles) of conidiophores which
grow out through stomata. These are carried to new leaves by rain splash,
and the disease cycle begins again.

 Choose disease resistant cultivars
 Start with certified, disease-free plants purchased from a
reputable nursery
 These cultural practices help reduce infections
 Plant in full sunlight in well-drained soil with good air
 Prevent weed growth by cultural or chemical methods.
 Take care in spacing runner plants in matted-row culture. Do
not allow an over-population of plants.
 Always remove the old infected leaves from runner plants
before setting.
 Apply nitrogen fertilizers only at renovation time.
Applications of nitrogen in the spring produce an
overabundance of young leaf tissue susceptible to leaf-disease

 Follow a fungicide spray schedule recommended for the
control of leaf diseases and fruit rots.
 The first spray should be made in the spring just before the
first blossoms open. For June-bearing cultivars, repeat the
fungicide applications at 7- to 10-day intervals through to final
harvest. An additional fungicide application should be made
on June-bearing cultivars a week or two after renovation.
Spray ever bearing cultivars at 7- to 10-day intervals during
the primary fruiting periods. The spray intervals can be
lengthened to two or three weeks for the remainder of the
 In seriously infected plantings, mow, rake, and destroy (burn)
all diseased strawberry debris at renovation time immediately
after harvest. In such plantings, fungicides should be applied
immediately after renovation and at 2- to 3-week intervals
until new foliar growth ceases in the fall

For organic strawberry growers
weekly applications of an OMRI-approved
copper or potassium bicarbonate have been
shown to be effective in mitigating strawberry
leaf spot.

2. Fruit rot
: Botrytis cinerea
Class : Leotiomycetes
Order : Helotiales
Family : Sclerotiniaceae

Economic importance:
The disease is serious problem in grapes, vegetables
and berries world-wide, especially when grown under


 The fungi will attack flowers, fruit, petioles, leaves
and stems
 Flowers and fruit stalks infected during flowering die
 Green and ripe fruit develop brown rot
 This spreads over the whole fruit, which becomes
covered with masses of dry, greyish spores
 The rot may start on any portion of the fruit, but is
found most frequently on the calyx end or on the
sides of fruit touching other rotten fruit

A: Mycelium growth on flower. B: An advanced floral infection.
C and D: Infections of fruit at different stages. D: An infected petal.
E and F: Browning of leaves

Favourable condition:

Low temperature, high humidity and frequent rain

Disease cycle:
• The fungi over-winters(Sclerotium) 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

 Remove and destroy dead or infected plant material
 Growing strawberries in plastic tunnels has proven to
effectively reduce the incidence
 Using plastic mulches to prevent berry-soil contact
also reduces disease except where water puddles
under the fruit on the plastic
 Neem oil or Liquid copper fungicides spray at seven
to ten days from the onset of flowering through
harvest to protect plants
 Potassium bicarbonate is also effective


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