Fungal diseases of fruit crops-Papaya

1. Fungal diseases of Fruit crops-
Papaya
Vaishali S.Patil
Professor, Department of Botany
Shri Shivaji College of Arts, Commerce & Science Akola

2. 1.Alternaria fruit spot- caused by Alternaria alternata
Symptoms-depressed, circular to oval, lesions that eventually
become black as a result of mass sporulation. Lesons are
restricted to the surface of the fruit and do not cause extensive
rotting of the flesh. However, lesions from multiple infection
sites can coalesce as they expand and eventually cover the
entire fruit surface.
Control-A single postharvest water dip of 20 min, fungicides.

3. 2.Angular leaf spot caused by Leveillula taurica
Symptoms- Petioles, stalks and flowers are rarely
affected and fruits are occasionally infected. It
penetrates the interior leaf tissues. On the ventral side
powdery, whitish spots appear that gradually expand.
On the dorsal side, yellow spots of varying intensity
develop. On the dorsal side, powdery spots may also
develop. Spots may later become necrotic.
Control- Crop Resistance, proper irrigation, chemical
control.

4. 3.Anthracnose caused by Colletotrichum gloeosporioides
Symptoms -The spots on fruits first appear as brown
superficial discolouration of the skin which develops into
circular, slightly sunken areas. Gradually the lesions coalesce
and sparse mycelia growth appears on the margins of the
spots. Infection at early stages of fruit results in
mummification and deformation.
Control-removing the fruit as soon as it matures, removing all
dead leaves and fruit from the vicinity of the plants, and
removing infected fruits from the trees.

5. 4.Black spot caused by Asperisporium caricae,
Cercospora papayae, Phomopsis caricae-papayae
Symptoms- Water-soaked spots appear on the upper
leaf surface. Later, small, black spots are visible on the
underside of the leaf. Black spots may also be found
on the fruit. The tissue beneath them becomes corky,
but the fruit does not rot.
Control-Fungicide

6. 5.Blossom spot caused by Choanephora cucurbitarum
Symptoms- Ringspot disease are exhibited on the foliage
fruit and main stem of the plant. The main stem growing at the
time of infection frequently develops dark-green spots and
streaks of an oily appearance. These are usually most common
on the middle two-thirds of the stem.
Control- Refrigerated storage and careful handling will
minimize decay postharvest.

7. 6.Black rot caused by Mycosphaerella caricae
Symptoms- Spots appear on leaves, flowers and young fruit.Fruit
surface lesions are slightly sunken, circular, black. Margins of lesions are
light brown and translucent. The lesion surface dries and wrinkles with
age and turns black as it becomes covered with hyphae and pycnidia of
the imperfect stage. Under humid conditions it is common to see light-
colored tendrils of pycnidiospores oozing from pycnidia. The infected
tissue is dry, firm and is initially tan in color and eventually turns black.
Infection of flowers and young fruit are initially brown then become dark
and sunken. Lesions often extend through the peduncle to the succulent
stem tissue where it too takes on the characteristic dark, sunken
appearance.
Control- Hot water treatment, fungicides

8. 7.Brown spot caused by Corynespora cassiicola, Cercospora
melonis,Cercospora vignicola, Helminthosporium cassiicola,
Helminthosporium vignae,Helminthosporium vignicola
Symptoms- On the lower leaves, small, angular brown spots, often with
white centres that fall out . The spots have a characteristic well-defined
yellow halos. Oval, dark brown spots also occur on the leaf stalks.
However, in wet conditions, the spots grow much larger, join together,
and develop into spots that are zoned, or have target-like rings. Spots on
fruits are not common, but occasionally occur as dark, sunken spots on
the fruits.
Control- Remove infected papaya trees from the field, fungicide.

9. 8.Chocolate spot caused by Colletotrichum gloeosporioide
Symptoms-superficial lesions, seldom slightly sunken,
irregular to rounded, well defined, with characteristic reddish-
brown colour. As the fruit ripens the lesions can either remain
superficial or grow and become sunken, resembling
anthracnose.
Control-Remove and destroy infected plants or plant parts and
do not compost them, use resistant/tolerant varieties,
plant certified, disease free/healthy planting materials,
plant trees in well-drained soil, ensure rotations with non-host
plants, ensure proper weed control, to prevent post-harvest
losses avoid fruit wounding, i.e.
through bruising, scratching,
or puncturing the fruits,
fungicides.

10. 9.Collar rot caused by Cylindrocladium crotalariae,
Calonectria crotalariae
Symptoms-The stem of the tree will become water soaked
and weak, usually right at ground level. This water-soaked
area will develop into a brown or black lesion and begin to
rot. Sometimes a white, fluffy growth of fungus is visible. The
leaves may turn yellow and droop, and eventually the entire
tree will fail and collapse.
Control-plant papaya saplings in well-draining soil. Dig up
infected plants and destroy them, and do not plant more
trees in the same spot.

11. 10.Damping off caused by Colletotrichum
gloeosporioides,Phytophthora palmivora,Phytophthora
nicotianae,Phytophthora parasitica,Pythium
aphanidermatum,Pythium debaryanum,Pythium
ultimum,Pythium sp.,Rhizoctonia solani,Thanatephorus
cucumeris
Symptoms- seeds fail to germinate & slowly kills young
plants. The fungus eventually rots out the stem.
Control-resistant varieties, fungicide, Prepare the soil well
and ensure that it drains quickly, crop rotation, Sanitize all
containers and tools.

12. 11.Dry rot caused by Phoma caricae-papayae,Ascochyta
caricae,Ascochyta caricae-papayae,Mycosphaerella caricae
Symptoms-Fruit surface lesions are slightly sunken, circular, black .
Margins of lesions are light brown and translucent. The lesion surface
dries and wrinkles with age and turns black as it becomes covered with
hyphae and pycnidia of the imperfect stage. Under humid conditions it is
common to see light-colored tendrils of pycnidiospores oozing from
pycnidia. The infected tissue is dry, firm and is initially tan in color and
eventually turns black. Stem-end rot caused by this fungus takes on the
characteristics similar to fruit surface lesions. Infection of flowers and
young fruit are initially brown then become dark and sunken. Lesions
often extend through the peduncle to the succulent stem tissue where it
too takes on the characteristic dark, sunken appearance.
Control-Hot water treatment, fungicide.

13. 12.Foot rot caused by Pythium aphanidermatum,Pythium ultimum
Symptoms -Water-soaked patches on the stem near the ground level.
These patches enlarge rapidly and girdle the stem, causing rotting of the
tissues, which then turn dark brown or black. Such affected plants
withstand strong wind and topple over and die.
If the disease attack is mild, only one side of the stem rots and the plants
remain stunted.
Fruit if formed are shriveled and malformed. Gradually the plant dies.
Control- well-draining soil, as well as irrigation that does not touch the
trunk. Applications of copper solution shortly after planting and during
the time of fruit formation will also help.

14. 13.Fruit rot caused by Monilia sp
Symptoms-Initial fruit lesions are brown, circular, and firm.
Eventually the whole fruit decays and turns brown. Tufts of
mycelium and conidia (cream-white to buff colored) sprout
from the skin of the infected fruit, often arranged in concentric
rings. Rotted fruits may either fall to the ground or dry out on
the tree, leaving a hard, shriveled ‘mummy’.
Control-fungicides, emoval of mummified fruit and pruning
of infected twigs, with subsequent burning or deep-burying,
and the removal of wild host plants.

15. 14.Fruit spot caused by Cercospora mamaonis
Symptoms-Fruit spots start as tiny black dots that eventually
enlarge. The spots are superficial, slightly raised, a result of
the tissue beneath the epidermis becoming corky, and do not
develop into a fruit rot. The spots are somewhat obscure on
green fruits but become readily visible when the skin color
turns yellow as the fruit ripens. Actual damage to fruits is
minor except its impact on their appearance and marketability.
Control-fungicide

16. 15.Fusarium fruit rot caused by Fusarium solani,
Fusarium spp.
Symptoms-small, pitted, corky spots to large, sunken areas
covered with a white or gray mold on fruit.
Control-Crop rotations, fungicide , Avoidance of wounding
during harvest and packing, storage in dry conditions, and
proper handling during transit and marketing reduce post-
harvest decay.

17. 16.Guignardia spot caused by Guignardia sp
Symptoms- Numerous, circular to oval, sunken
greenish-black lesions expand in diameter very slowly
, the fungus may grow deep into the flesh causing a
black, firm discoloration.
Control-heat treatments.

18. 17.Greasy spot caused by Corynespora
cassiicola,Cercospora melonis, Cercospora vignicola,
Helminthosporium cassiicola, Helminthosporium vignae,
Helminthosporium vignicola
Symptoms-The leaf spots are grayish-white, subcircular to
irregular, heavily infected leaves turn yellow and dry up. The
fruit spots start as tiny spots which turn black and enlarge. The
tissue just beneath the epidermis of the fruit becomes corky;
the spot does not develop into a fruit rot.
Control-Fungicides

19. 18.Internal blight caused by Cladosporium sp.,
Fusarium sp., Penicillium sp.
Symptoms-
Infected tissue is watersoaked and translucent in the early
stages to black and firm in the later stages of infection.
Infected fruits yellow prematurely and unevenly in the fruit
column.
Control-proper seed selection, fungicides.

20. 19.Lasiodiplodia fruit rot caused by Lasiodiplodia
theobromae, Botryodiplodia theobromae, Botryodiplodia
gossypii, Diplodia theobromae, Diplodia gossypina, Diplodia
natalensis, Lasiodiplodia triflorae
Symptoms- A wider, more extensive translucent margin on fruit
,mummify the entire fruit. Gray mycelium forms over the infected area
and later turns black from the masses of pycnidia that form. The infected
flesh takes on a bluish-black discoloration in the soft water-soaked
tissue. Air pockets often form in the infected area, presumably caused by
the flesh shrinking, and later become filled with gray mycelium
Control- hot water treatment.

21. 20.Leaf spot caused by Alternaria sp., Asperisporium
caricae, Cercospora mamaonis, Cercospora papayae,
Choanephora cucurbitarum, Curvularia caricae-papayae,
Gloeosporium sp., Phoma caricae-papayae, Mycosphaerella
caricae, Phyllosticta sp.
Symptoms- irregular dark brown to black spots appear on
the lower leaf surface of leaves. On the upper leaf surface,
the infection causes slightly sunken tan spots to occur. Black
spots have also been observed on the surface of fruits.
Control- fungicides.

22. 21.Petiole spot caused by Didymella sp.
Symptoms- It causes moist dark brown stem cankers that
often develop from de-leafing and other wounds. These
lesions gradually spread and eventually surround the stem
and/or petioles, thus disrupting the sap flow. Ultimately,
yellowing and wilting of the leaflets and plant parts below the
lesions.Brownish tiny globular structures (pycnidia) dot the
damaged tissues.
Control- Long rotations with crops, Wounding fruit during
harvest and in storage must be avoided, resistant
varieties,fungicides.

23. 22.Phytophthora blight caused by Phytophthora palmivora,
Phytophthora nicotianae var. Parasitica, Phytophthora parasitica
Symptoms- Water-soaked lesions exude milky latex. Fruits may
eventually mummify and fall. Large lesions, often forming first where
the fruit contacts the stem of the plant, are covered with whitish
mycelium and masses. Fruits can rot, turn soft, and fall prematurely. As
lesions enlarge, infected areas of the stems way weaken, causing stem
damage or breaking. Foliage on affected stems may collapse. Roots may
become dark and rotten, causing stunting of plant growth and yellow,
collapsed leaves. Severely infected plants may die.
Control- well drained soil, steamed or fumigated prior to planting, hot
water treatment, Avoid damage or injury to papaya stems during
cultivation, Variety selection, fungicides.

24. 23.Powdery mildew caused by Erysiphe cichoracearum, Erysiphe sp.,
Oidium caricae, Oidium indicum, Ovulariopsis papayae, Sphaerotheca
fuliginea, Sphaerotheca humuli
Symptoms- On the undersurface of disease leaves are found patches of
whitish powder growth.
On upper surfaces, leaves at the infection site show blotches of yellow or
pale green usually near vein, surrounded by normally colored tissue.
Fungus may attack the stem of young seedling. The spots enlarge and
cover the entire leaf area. Severely infected leaves may become chlorotic
and distorted before falling. Affected fruits are small in size and
malformed.
Control-Fungicide

25. 24.Phytophthora fruit rot caused by Phytophthora capsici,
Phytophthora nicotianae var., parasitica, Phytophthora
parasitica, Phytophthora palmivora
Symptoms-Water-soaked lesions exude milky latex. Fruits
may eventually mummify and fall, fruit rot initially appears as
small, circular, water-soaked lesions. Large lesions, often
forming first where the fruit contacts the stem of the plant, are
covered with whitish mycelium and masses. Fruits can rot,
turn soft, and fall prematurely.
Control- well drained soil, pick up, remove and destroy fallen
fruits, Intercrop, steamed or fumigated, hot water, Avoid
damage or injury,fungicides.

26. 25.Rhizopus soft rot caused by Rhizopus stolonifer,Rhizopus
nigricans
Symptoms-soft and watery rot that quickly collapses the
entire fruit but leaves the cuticle intact. The fungus can grow
out through any break in the cuticle and spread rapidly to
adjacent fruits, often destroying the entire contents of a box
within a few days. The infected fruit is often covered by
coarse, gray, hairy mycelia that form a mass of black
sporangia at their tips.
Control-sanitation, use of chlorinated water tanks, wounds
should be minimized, Heat treatment, fungicide.

27. 26.Root rot caused by Phytophthora palmivora, Pythium
aphanidermatum, Pythium ultimum, Pythium spp., Rhizoctonia solani,
Thanatephorus cucumeris
Symptoms-Ripe and unripe fruit are infected while still attached to the
stem; lower fruit are infected first. Rots develop quickly and become
covered in a white growth containing spores of the water mould, causing
the fruit to shrivel and fall. Stems, also become infected through leaf and
fruit scars. Rots develop, and these cause the tops of the trees to wilt and
die. Rots also form at the base of the stem near soil level; in this case the
decaying roots are the source of infection. Roots become infected with a
soft, wet rot that affects the taproot and surface roots as well as the base
of the stem. Leaves wilt, turn yellow and collapse, with only a few small
leaves remaining at the top of the tree.
Control-Soil drainage, crop rotation, hygiene, fungicides.

28. 27.Sclerotium blight caused by Sclerotium rolfsii, Athelia rolfsii
Symptoms - development of coarse white strands of mycelium growing
in a fan-shaped pattern on lower stems, leaf litter, and soil . After 7 to 14
days, tan-to-brown, mustard-seed-sized sclerotia form on the mycelial
mat. Early symptoms consist of water-soaked lesions on crown and
lower stem tissue. The disease usually is recognized by the yellowing
and wilting of foliage, followed by a complete collapse of the plant. Soft,
water-soaked, sunken, slightly yellowish lesions develop on fruit. These
lesions quickly spread throughout most or all of the fruit, which will
eventually become soft and collapse within 3 to 4 days of infection. The
skin of the fruit often crack open and fine white mycelium and
developing sclerotia spreads over the surface and quickly fills lesion
cavities
Control-Crop rotations, selecting
fields that are free of S. Rolfsii,
Close plant spacing & over-irrigation,
Injury during cultivation should be
Avoided deep plowing, fungicide,
fumigants, Biological Control.

29. 28.Seedling blight caused by Colletotrichum gloeosporioides
Symptoms- causing cotyledon or leaf spots, defoliation, stem
lesions, collar rots, and damping-off. Over 80% of the
seedlings were diseased in 3 weeks. The fungus spread from
leaf or cotyledon lesions to stems and eventually caused stem
or collar rot and damping-off.
Control- The affected fruits should be remove and destroyed.
The fruits should be harvested as soon as they mature, hot
water treatment or a fungicidal wax treatment.

30. 29.Stem-end rot caused by Alternaria alterneta, Colletotrichum gloeosporioides,
Fusarium sp.Lasiodiplodia theobromae, Botryodiplodia theobromae, Botryodiplodia
gossypii, Diplodia theobromae, Diplodia gossypina, Diplodia natalensis,
Lasiodiplodia triflorae, Phoma caricae-papayae, Ascochyta caricae, Ascochyta
caricae-papayae, Mycosphaerella caricae, Phomopsis sp.Rhizopus stolonifer
Symptoms- A dark rot develops from the stem end as fruit ripen after harvest. A dark
brown to black rot begins at the stem end as a dark brown ring and the rot proceeds
towards the other end. The rot produces dark streaking of the water-conducting tissues
Control- fungicide, Avoid harvesting immature fruit. Cool fruit immediately after
harvest and store in well-ventilated containers.

31. 30.Stemphylium fruit spot caused by Stemphylium
lycopersici, Thyrospora lycopersici, Stemphylium
floridanum
Symptoms- fruit spot are small, round, dark brown lesions.
The lesions become sunken and develop reddish-brown to
purple margins as they enlarge. A velvety, dark green spore
mass forms in the lesion center. White to gray mycelia grow
over the lesion in the advanced stages. Internally, the infected
tissue is discolored from a reddish brown to a dark brown
color, appears dry, and small air pockets may develop.
Control- hot and cold treatments, fungicides.

32. 31.Stem rot caused by Fusarium solani, Nectria haematococca,
Fusarium sp., Phytophthora palmivora, Pythium aphanidermatum,
Pythium ultimum
Symptoms-The stem of the tree will become water soaked and weak,
usually right at ground level. This water-soaked area will develop into a
brown or black lesion and begin to rot. Sometimes a white, fluffy growth
of fungus is visible. The leaves may turn yellow and droop, and
eventually the entire tree will fail and collapse.
Control-plant papaya saplings in well-draining soil. When planting
saplings, handle them with care. Dig up infected plants and destroy them

33. 32.Target spot caused by Phyllosticta caricae-papayae
Symptoms-The spots, on the leaves, vary considerably in size, some
being small and rounded or irregular, oval, or elongated, almost white in
the centre, they are often bounded by a yellowish or brownish margin
which merges into the normal green of the leaf. The central portion of the
spots is thin and papery, and finally it becomes brittle and drops out.
When numerous spots are present, the leaf withers and falls.
Control-Removing and destroying leaves from trees infected with eye
spot, wetting foliage during irrigation should be avoided, Air circulation
may be improved by pruning and by preventing overcrowded plantings.
avoid susceptible species and cultivars , fungicide .

34. 33.Verticillium wilt caused by Verticillium dahliae
Symptoms-Sudden wilting of leaves on one or more
branches, rapid browning. Can start at base and move
upwards. Young trees may be killed. Older trees may
become stunted and lose productivity. Vascular tissue
may be stained.
Control-Avoid planting in known infected soils or
fumigate soil.

35. 34.Wet fruit rot caused by Phomopsis sp.
Symptoms- The infected area is slightly depressed, soft and translucent.
The fungus is rapid growing causing lesions to expand very quickly with
the infected area extending to the seed cavity. The cuticle over the
infected area remains intact and develops a delicate, wrinkled pattern that
is parallel to the leading edge of the lesion. Black, scattered pycnidia
usually form in the infected area after about seven days. The infected
tissue is soft, mushy and wet. The infected area can become covered by
white to gray mycelium.
Control-Removing dead and senescing leaves and petioles from the tree,
hot water treatment for 20 minutes at 48C, fungicides.