Pstachio diseases A Lecture on ToT By Allah Dad Khan

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

5. Alternaria late blight (Alternaria leaf spot)
Symptoms
•
• Black angular to circular lesions of leaves which
enlarge and coalesce, forming tan patches; small
black lesions on immature nuts; lesions enlarge and
coalesce; staining on hull; moldy kernels; severe
infestation on leaves can cause premature
defoliation
• Cause
• Fungus
• Comments
• Disease emergence favors high temperature and
high humidity; fungus survives on plant debris
• Management
• The disease is difficult to control and all pistachio
cultivars used commercially are susceptible;
applications of appropriate fungicides may help to
reduce the incidence of the disease; good irrigation
practices should be followed; practices that reduce
the wetness of the ground around plants is
recommended

6. Armillaria root rot (Oak root fungus) Armillaria mellea
Symptoms
• Small, discolored leaves which drop early;
death of branches; death of plant; clusters of
honey-colored mushrooms may sprout at
base of plant
• Cause
• Fungus
• Comments
• Fungus can survive on dead roots
• Management
• Armillaria root rot cannot be effectively
controlled once it has become established in
an orchard; diseased or dead plants should
be uprooted and removed; planting resistant
rootstocks is the most effective method of
preventing the disease
•

7. Powdery mildew Phyllactinia guttata
Symptoms
• Small powdery white patches on leaves
and fruit which can expand to cover the
entire leaf or fruit surface; small black
fungal fruiting bodies are often visible
in the white patches
• Cause
• Fungus
• Comments
• Disease emergence favored by
moderate temperature, poor air
circulation around plant and shady
conditions
• Management
• Disease does not cause severe damage
to pistachio and control is not
warranted

8. Pistachio Botryosphaeria Panicle and Shoot Blight
Symptoms
• Vegetative and flowering buds that
were killed during the previous fall
or winter do not emerge in spring.
In mid-spring (end of May to June)
buds that were partially infected
the previous season produce fruit
clusters and shoots that develop
blight from the fungus in buds. The
rachises of these blighted clusters
turn black as do the shoots. When
temperatures increase in May
through July, the fungus moves into
shoots of the previous year, causing
blighting of fully developed
clusters. These blighted shoots,
leaves, and clusters turn brown.

9. Pistachio Phytophthora Root and Crown Rot
Pathogens: Phytophthora spp.
SYMPTOMS AND SIGNS
• Pistachio is subject to root and crown
rots and trunk and branch cankers.
Trees show poor vigor; leaf yellowing,
wilting, and scorching; and shoot and
branch dieback. Infected roots become
necrotic, with dark brown to black
discoloration of the cortex and stele.
Small roots eventually disintegrate.
Cankers develop at the root crown and
may extend above the soil line. Infected
pistachio bark turns brown to black.
Active cankers often ooze and release a
light cream exudate in balls, strands, or
puddles. The exudate is not diagnostic
because other diseases and injuries to
the trunk will result in sap release

10. Pistachio Verticillium Wilt Pathogen: Verticillium dahliae
SYMPTOMS AND SIGNS
• Generally Verticillium wilt
causes a rapid desiccation
and death of one or more
scaffolds or the entire tree,
usually in late spring or
early summer. The first
symptoms are interveinal
patches of yellowing or
scorching of the leaves on
affected branches.

11. Pistachio
Fruit Pathogens: Alternaria alternata,
Fusarium spp., Stemphylium sp.,
Symptoms
• Alternaria causes deterioration of
fruit epicarp (see
also ALTERNARIA LATE BLIGHT
DISEASE). Small or large black
lesions develop that may expand
over the entire hull surface.
Depending on the degree of
colonization, A. alternata can
invade the kernel, causing kernel
discoloration and decay. Whether
or not the kernel is
infected, Alternariacan damage
the quality of the nut by causing
brown to black stain marks on the
shells.