This document describes symptoms of several blueberry diseases including: 1. Botrytis blight of blueberry causes gray sporulation of Botrytis cinerea fungus and is treated only after frost or cold spells damage blooms. 2. Mummy berry disease causes small cup-shaped fungal structures on berries and leaves and mummified berries that overwinter and spread infection the next spring. 3. Alternaria leaf spot appears as circular brown lesions with red borders on leaves during cool, wet weather and can defoliate plants or damage post-harvest fruit. 4. Several other diseases that cause leaf spots, stem cankers, wilting, and root rot in blueberries are also

2. Blue Diseases
A
Lecture To Berry ToT trainees ( FFS)
By
Mr. Allah Dad Khan
Provincial Coordinator IPM KPK
MINFAL Pakistan

3. Botrytis Blight of Blueberry
Symptoms
Gray sporulation of Botrytis
cinerea.
 Botrytis will usually cause
losses early in the
growing season, but a lot
of rainy weather during
the spring may also lead
to Botrytis problems. It is
not recommended to treat
preventatively for this
disease. Treat only if there
is a frost that damages
blooms or if there has
been a significant cold
spell.

4. Mitigating Mummy Berry Disease of
Blueberry
Symptoms
Mummy berry disease of
blueberry.
 During the first, the blighting
stage, small, cup-shaped
structures bearing the fungus'
spores sprout from berries
concealed among leaf litter in
the ground. Wind spreads the
spores to nearby plants,
infecting newly emerging
shoots and leaves. During the
second phase, the fungus
penetrates the berry, causing it
to shrink, shrivel and turn
whitish-hence the "mummy"
reference. Eventually, the
mummified fruit drops to the
ground and overwinters, setting
the stage for a new round of
infection the following spring.

5. Mummy Berry Disease of Blueberries
Symptoms
Fruit infection stage of the mummy
berry
disease
 Mummy berry, a disease
caused by the
fungusMonilinia vaccinii-
corymbosi, is an important
pathogen in many blueberry-
growing regions of the
United States. Infected
berries are unsightly and
unmarketable.Severely
infected fields can suffer
heavy yield losses. In
addition, severe blighting of
emerging leaf shoots and
flower clusters can occur on
susceptible cultivar

6. Alternaria Leaf Spot of Blueberry
Symptoms
Alternaria Leaf Spot (Alternaria
tenuissima) occurs primarily in the
spring during prolonged periods of cool
wet weather, when spores are
produced in abundance. In most cases
only lower leaves are affected;
however, instances do occur when
severe infection completely defoliates
the plant. Because of its importance as
a postharvest fruit decay organism, an
increase of the fungus on blueberry
leaves in May can result in
considerable damage to fruit after
harvest. Leaf symptoms appear as
circular to irregular-shaped brown to
gray lesions surrounded by a red
border. Prolonged periods of high
humidity favor disease development.

7. Bacterial Leaf Scorch of Blueberry
Symptoms
 Symptoms on southern
highbush blueberries
include: marginal
scorching of the leaves,
premature leaf drop,
yellowing of stems and
eventual death of the
plants

8. Septoria Leaf Spot of Blueberry and
Grape
Symptoms:
 Small to medium brown
leaf spots with purplish
margins.
 Lesions on succulent
green stems.
 Premature defoliation of
bushes.

9. Leaf Rust of Blueberry
Symptoms
 The disease first appears as
yellow leaf spots on the
upper leaf surface of new
blueberry leaves.
 Spots later turn reddish
brown. Entire leaves may
turn brown, die and drop
prematurely if infections are
severe.
 Yellowish orange pustules
become visible on the lower
leaf surface about mid-
summer. This disease also
occurs sporadically on
highbush blueberries after
harvest.

10. Botryosphaeria Stem Canker of Blueberry
Symptoms
 Early symptoms are small
red lesions on succulent
stems. The lesions
become swollen and
broadly conical in about
six months. On
susceptible cultivars,
large, swollen cankers
develop, with deep cracks
and numerous fruiting
bodies, after two to three
years. Stems may be
girdled and killed.

11. Stem Blight of Blueberry
Symptoms.
 Plants exhibit a rapid wilt
with browning or reddening
of leaves on individual
branches, sometimes
followed by death of the
entire plant as the fungus
spreads downward through
vascular tissue to the base
of the plant. Wilting occurs
so rapidly that the stem does
not defoliate before dying,
resulting in “flagging,” a
dead or dying stem with
attached brown leaves.

12. Armillaria Root Rot of Blueberry
Symptoms
 Infected plants are low in vigor and
may appear to suffer from a
nutrient deficiency.
 Leaves are small and cholortic.
 Branches wilt suddenly.
 Plants decline over several years
or die within a short time.
 Black shoestring-like strands
(rhizomorphs) may be attached to
the roots or trunk or growing freely
in the soil.
 Yellowish brown mushrooms
(honey mushrooms) are
sometimes produced in clumps at
the base of the bush.

13. Phytophthora Root Rot
Symptoms
 Early above-ground symptoms
include:
 Leaves turn yellow.
 Leaf margins burn.
 No new leaf growth
 As disease progresses:
 Terminal leaves become small
 Excessive defoliation occurs
because of severely damaged roots.
 Stunted and wilt-prone leaves.
 Restricted root system that allows
plants to be easily rocked back and
forth, or pulled up.
 Dead or prematurely defoliating
bushes.
 Defoliation and poor growth follow
the contours of the low areas where
excessive moisture is present.