This document summarizes several common diseases that affect avocado trees: - Anthracnose causes chlorotic and necrotic spots on leaves and fruit and can lead to defoliation. It is caused by the fungus Glomerella cingulata and spreads through rain splash. Management includes pruning dead material and maintaining dry conditions. - Scab appears as brown or purple spots on fruit and is caused by the fungus Sphaceloma perseae. High humidity encourages its spread. Copper fungicides and tolerant varieties can help control it. - Phytophthora root rot causes black lesions on roots and leads to premature leaf drop and yield decline. The oomycete Phytoph

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

3. Anthracnose symptoms Anthracnose symptoms
Anthracnose
Glomerella cingulata

4. Anthracnose symptoms Anthracnose symptoms
Anthracnose

5. Anthracnose symptoms Anthracnose symptoms
Anthracnose

6. Symptoms
 Chlorotic and necrotic spots; dead
leaf tip; defoliation; brown or purple
lesions on new shoots
 Cause
 Fungus
 Comments
 Spores spread by rain splash; high
moisture and warm temperatures
encourage spread
 Management
 Prune dead twigs and branches from
tree before fungi produce spores;
knock dead leaves out of canopy;
keep harvested fruit dry and cool
Chloratic Disease

7. Avocado scab Scab symptoms
Scab Sphaceloma perseae

8. Symptoms
 Oval or irregular brown or
purple spots on fruit with
rough texture
 Cause
 Fungus
 Comments
 High humidity encourages
scab growth and spread
 Management
 Plant tolerant varieties; spray
with copper containing
fungicides
Purple Spot

9. Symptoms
 Elongated black streaks on bark; cankers
parallel to growth of limbs; black blotches
with distinct margins on green wood;
cankers on bark cause cracks which ooze
sap; removal of bark over cankers reveals
dark discoloration underneath
 Cause
 Unknown
 Comments
 Disease emergence favors adverse growing
conditions for avocado; more common in
Guatemalan cultivars
 Management
 Avoid stressing trees by following good
fertilization and irrigation practices
Black streak Avocado black streak

10. Symptoms
 Black lesions on roots; black, brittle roots;
small, yellow leaves; premature leaf drop;
decline in fruit yield
 Cause
 Oomycete
 Comments
 Wet soils encourage Phytophthora
infection; plant in a well draining soil.
 Management
 Minimize water splash between trees by
not working in a wet orchard; prune out
dead limbs and twigs; remove fruit from
the ground; dispose of dead wood and
fruit away from trees
Phytophthora root rot and crown rot
Phytophthora cinnamomi

11. Fruit symptoms of P.
citricola
Tree trunk with symptoms
of Phytophthora citricola.
Phytophthora

12. Symptoms
 Shrivelled tissue at stem end; dark brown
or black lesions at stem end and
eventually over entire fruit; fruit covered
in mycelium
 Cause
 Fungi
 Comments
 Environmental conditions may determine
which fungal species is most common;
spores can spread by wind or rain.
 Management
 Prune dead limbs and twigs; prune and
harvest in dry conditions; provide trees
with sufficient irrigation; apply a thick
layer of mulch
Stem-end rot

13. Symptoms
 Symptoms
 Gray to black, mushy, foul smelling rot on fruit;
fruti has darkened metallic sheen
 Cause
 Bacteria
 Comments
 Bacteria may be present on leaves but do not
cause damage unless plant is stressed or bacteria
enter the plant through a wound
 Management
 No treatment for disease; use certified seed;
disinfected tools and cuttings; employ crop
rotation; remove plant debris from soil


14. Symptoms
 Red, yellow, pink or white streaks
running the length of young
stems; white, yellow or red
blotches on fruit
 Cause
 Viroid
 Comments
 Can be transmitted by grafting
 Management
 Frequently sanitize all pruning
equipment with disinfectant;
plant only certified nursery stock
Avocado sunblotch viroid (ASBVd)

15. Algal leaf spot symptoms Algal leaf spot symptoms
Cephaleuros virescens

16. Symptoms
Algal leaf spot symptoms
 Raised, orange-red spots
on both upper and lower
surfaces of leaves; spots
may coalesce to form
irregularly shaped
patches; spots may also
be present on twigs and
branches; when the
surface of the spot is
scraped away, a gray to
dark necrotic crust is
visible
Algal Leaf Spot