This document discusses various diseases that affect apricots, including their symptoms and causal agents. It describes fungal diseases like Armillaria root rot, Eutypa dieback, brown rot blossom, and fungal gummosis. It also discusses bacterial diseases like bacterial canker and crown gall. Other diseases mentioned include Verticillium wilt, plum pox virus, bacterial spot, peach leaf curl, peach mosaic virus, peach scab, peach yellows, Rhizopus rot, and rust. For each disease, the summary provided the causal organism and key symptoms.

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

3. Armillaria root rot Armillaria mellea
Symptoms
• If tree is infected after it has
reached 5 years of age then
typical symptoms include poor
terminal growth and small
leaves; around midsummer the
whole tree suddenly collapses;
in orchards trees usually die in
a circular pattern; infected
trees often have a fan-shaped
white fungal mat growing
between the bark and wood of
the crown

4. Eutypa dieback Eutypa lata
Symptoms
• Cankers on branches, usually
associated with a pruning
wound which is several years
old; discolored sapwood may
extend abovwe and below
canker; leaves on branches
around canker may suddenly
wilt as branch dies; leaves
remain attached to branches;
discoloured bark and inner
wood; gummy amber exudate
may be present

5. Brown rot blossom Monolinia spp.
Symptoms
• Death of young blossoms and
associated twigs and leaves;
small tan cankers with dark
margins on twigs; gummy
exudate at base of flowers;
brown spore masses on
flowers in humid conditions

6. Fungal Gummosis (fungus – Botryosphaeria
dothidea):
Symptoms
• The fungus enters through
wounds or lenticels on lower
parts of scaffold limbs and the
trunk. Older infection sites
typically exude gummy resin.
Necrosis is associated with
infection but usually is restricted
to the area just under the bark.
Over time the bark develops a
rough texture. Trees can recover
somewhat if infection is not
severe. Stressed trees are
damaged the most

7. Jacket rot Botrytis cinerea clerotinia sclerotiorum
Monilinia laxa Monilinia fructicola
Symptoms
• Brown discoloration of fruit
under jacket occurring while
flower parts still attached to
fruit

8. Phytophthora root and crown rot
Phytophthora spp.
Symptoms
• Poor new growth; leaves
chlorotic, small in size and
sparse; fruit may be small,
brightly colored and susceptible
to sunburn; shoots may suffer
from dieback and tree will often
die within weeks or months of
first signs of infection or decline
gradually over several seasons;
root crown may show signs of
decay which develops into a
canker; bark of infected crown
tissue turns dark brown; cankers
may occur on aerial parts of
plant

9. Powdery midew Sphaerotheca pannosa
Podosphaera tridactyla
Symptoms
Powdery mildew symptoms on apricot fruit
• Round powdery white patches
of fungal growth on fruits and
leaves; rusty patches on fruits
which turn brown and leathery
and may crack

10. Ripe fruit rot Monilinia fructicola Monilinia laxa
Symptoms
Symptoms of ripe fruit rot on apricot fruits
• Dark brown circular spots on
fruit; tan spore masses may be
visible in center of spots;
diseases fruit may not drop
from tree

11. Shot hole disease Wilsonomyces carpophilus
Symptoms Shot hole disease spots on fruit and
holes in leaves.
• Brown lesions with purple
edge on fruit, twigs and buds;
holes in leaves due to lesions
which have dried and dropped
out; brown lumps developing
in the center of lesion (visible
with hand lens); buds turning
brown or black and exuding
sap; tan lesions with brown
margins which exude sap on
twigs

12. Shot Hole Disease

13. Shot Hole Disease

14. Verticillium wilt Verticillium dahliae
Symptoms
• Withering of leaves on one or
more spurs on 1 year old
wood; leaves are dull and
stunted; fruit small; older
cherry trees do not recover
from disease

15. Bacterial canker Pseudomonas syringae
Symptoms
• Cankers on twigs at bases of
flower and leaf buds, in
pruning wounds or at the base
of spurs which exude amber
colored gum; cankers spread
upwards and form sunken
areas in winter; if pathogen
enters dormant buds they may
be killed or open normally in
Spring before collapsing in
early Summer; infected buds
may be symptomless

16. Bacterial Canker

17. Crown gall Agrobacterium spp
Symptoms
• Galls on root and/or crown of
tree which can range in size
from so small they are not
visible to the naked eye up to
10 cm (4 in) in diameter; galls
first become visible as white,
fleshy swellings that grow
rapidly and become tan to
brown in color; galls typically
develop at the site of a wound
and new galls form adjacent to
old ones the next year

18. Crown Gall

19. Rust Tranzschelia discolor
Symptoms
• Pale yellow-green spots on
both upper and lower leaf
surfaces which are angular in
shape and turn bright yellow
in color; spots on lower leaf
surface develop orange-red
spores

20. Plum pox virus Plum pox virus (PPV)
Symptoms Symptoms of plum pox virus on apricot
fruits
• Pale green chlorotic spots,
rings and lines on leaves which
appear in early summer; pale
rings, lines and spots on fruit;
fruit flesh dry and flavorless;
fruit may be markedly
deformed

21. Bacterial Spot (bacterium – Xanthomonas
campestris pv. pruni)
Symptoms
• Symptoms on leaves are
observed first as small, circular,
or irregularly shaped, pale green
lesions During early
development, lesions almost
always are concentrated near
the leaf tip. In advanced stages,
the inner portion of the lesion
falls out, giving the leaf a
“ragged” or “shot hole”
appearance. Leaves heavily
infected with bacterial spot turn
yellow and fall. Repeated
infection can occur throughout
the growing season as long as
the environment is favorable.

22. Bacterial Spot

23. Leucostoma Canker (fungus – Leucostoma cinata –
anamorph Cytospora leucostoma):
Symptoms
• The fungus is a weak pathogen and
is rarely a problem in well managed
orchards with rapidly growing trees.
Pimple-like bumps develop on the
surface of cankers. During the
growing season small streams of
gum are formed at each pimple. In
most cases a callus layer forms
around the damaged area and the
canker is walled off. In a few cases
the canker growth will resume in the
fall after the callus growth is slowed.
Leucostoma canker may become
established in a limb through
pruning cuts or sunburn injury.
Affected trees should be pruned to
remove the canker sites and
fertilized to promote growth

24. Peach Leaf Curl (fungus – Taphrina
deformans):
Symptoms
• The peach leaf curl fungus
infects leaves, flowers, and
fruits. Infected leaves are
characterized by puckering,
thickening and curling.
Diseased leaves become pale
yellow to light green and shed
after a short tim

25. Peach Mosaic (virus)
Symptoms
• This viral disease affects peach
and plum. General symptoms
are delayed foliation, and small,
narrow, crinkled, mottled,
yellow leaves. Internodes are
shortened, and lateral buds
break, giving a rosette
appearance. The few fruit
produced are deformed resulting
in bumpy, misshapen, small
fruit. Spread is by grafting and
the peach bud mite, Eriophyes
insidiosus. Remove all virus-
infected trees as soon as they are
discovered.

26. Peach Scab (fungus – Cladosporium carpophilum):
• Peach scab, also known as
“freckles,” is found wherever
peaches are grown. It is most
apparent on mid-late season
varieties. Small spots develop on
fruit and are normally concentrated
around the stem or shoulder of the
fruit (See Photo). Lesions formed
on young twigs serve as a means of
overwintering. Primary infection in
the spring comes from spores
produced in twig cankers formed
the previous year. Fruit infection
normally occurs after shuck split
and 2-4 weeks following. Once
infection occurs, 40 to 70 days may
elapse before symptoms are visible

27. Peach Yellows (phytoplasma):
Symptoms
• The disease has been observed in
Texas but is rarely found. Fruits on
diseased trees ripen from a few days
to three weeks prematurely, have a
bitter taste, and are reduced in size.
Varieties which normally have red
skin are abnormally bright. Leaves
are chlorotic, fold upward, and tend
to droop. Infected trees leaf out
prematurely. The disease is spread
by grafting and feeding by the plum
leafhopperMacropsis
trimaculata (Fitch). After infection,
it may be 40 days to three years
before disease symptoms are visible.
Use only bud wood from healthy
trees and destroy any trees which
show typical disease symptoms.

28. Peach Yellow

29. Rhizopus Rot (fungus – Rhizopus stolonifer)
Symptoms
• This fungus is most active during
warm, humid weather. Fruit
infection results in a “black
whiskered” appearance caused by
fungal strands which produce an
abundance of black spores.
Rhizopus attacks peaches and
plums only at maturity. Disease
prevention is primarily based on
orchard sanitation, preharvest
fungicides, and rapid refrigeration
of processed fruit. Picking
containers should be such that fruit
receives a minimum amount of
handling. Packing equipment
should cause minimum injury. Pad
any area where fruit will drop onto a
belt or roller.

30. Rust (fungus – Tranzschelia discolor):
• Reddish-brown pustules occur
on the lower leaf surface
marked by a yellow spot on the
upper surface It causes
premature defoliation which
reduces tree vigor. The rust
species that infects peach does
not infect plum. In most parts
of Texas rust is a late season
disease that generally does not
require treatment