2. Anthracnose & Die Back
Reference Book:
Diseases of Fruit Crops
By R.S. Singh
Pg#161
3. Casual Organism
Colletotrichum gloeosporioides Penz.
Anamorph of the Ascomycetous fungi Glomerella cingulata (Ston.) Spould and
Shrenk, is a widely distributed funga causing leaf spot and anthracnose on citrus,
sugarcane, etc.
In addition to C. gloeosporioides, many other fungi are reported to be associated
with die-back leaf blight, and fruit rot symptoms on mango.
4. Economic Importance
Association with leaf spots, blossom blight
is a widespread disease
has major economic importance in areas where mango is grown commercially.
reported from many countries including Pakistan, India, Philippines, Indonesia,
Trinidad, Peru, Hawaii and Portugal.
occurs on all parts of the tree but is most common on flowers and flower stalks.
Young and mature fruits are also infected. If early infection of fruits takes place they
fall off.
Infected ripe fruits are blemished hence fetch a low price in the market. In storage
the anthracnose leads to postharvest storage rot.
5. Symptomology
The leaf spot and twig anthracnose is characterized by leaf spots, wither-tip and
blossom blight.
Young leaves are most susceptible
Numerous oval or irregular, brown to black spots appear on the leaf blade
restricting further growth of the leaf
Under humid conditions these spots increase rapidly and form irregular, necrotic
areas
Sometimes, the dead parts of the blade separate and fall down. Badly affected
leaves may also shed.
In wet and warm weather, acervuli of the fungus develop as pink bodies on the
dead and infected parts. Later, these fungus structures turn black.
In blossom blight, minute, brown to black lesions appear on floral parts and floral
stalks. Affected flowers in the panicle dry and shed. This causes significant loss to
fruit setting
6.
7. Epidemology
Conidial production in acervuli is favored by temperatures of 10°-30°C and a
relative humidity of 95-97%.
The fungus does not grow at a relative humidity less than 95%.
Thus, humid and misty conditions, temperatures of 24°-32°C, especially at the time
of development of shoots, flowers and fruits, are considered most favorable for
infection
8. Disease Cycle
Diseased twigs, leaves and dried fruits on the tree and on the orchard floor are a prolific
source of perenation of the fungus and fresh infections.
The pathogen can survive as leaf spots on the tree throughout the year
On the fruits, infections take place from the start of the blossoming until fruits are more
than half grown.
Infection pegs from the aspersoria enter the fruit through pores in the skin but the
infection remains latent and the fungus grows only to a limited extent in the epidermal
layers of the fruit.
Further growth of the fungus usually occurs during ripening of the fruit.
Latent infection can occur through lenticels also. Aspersoria have an important role in
epidemiology of anthracnose. Most of the aspersoria from germ tubes of conidia
lodged on the fruit do not germinate immediately but remain firmly attached to the
fruit skin as the latent stage of the pathogen. These latent aspresoria serve as inoculum
that gives rise to anthracnose spots on ripe fruits.
9. Management
Tree and general orchard sanitation
Vigorous growth of trees should be maintained by proper fertilization
Pruning and Destruction of Diseased Branches
4 to 5 Sprays of Fungicides
Use of resistant variety
14. Epidemiology
Fungus is favored by Cloudy weather and Heavy mist
Disease is more severe during cool, DRY weather.
minimum, optimum and maximum temperature for germination are 9º,22ºand 30º-
32º
Conidia grow well in temperature 9º-32º.
15. Disease Cycle
Fungus survives as mycelium
Conidia on the tree branches and also on other annual and perennial hosts.
In favorable weather conidia formed on, the mycelium are dispersed by wind and
spread the disease.
The optimum temperature for germination of conidia is 22°C, maximum 32°C and
minimum 9°C. The conidia are quickly destroyed in dry weather and under strong
sunlight.
Generally, cold nights, light rains or foggy weather at the time of flowering favor
initiation of the disease. the disease destroys mango panicles during the second half of
March when average minimum temperatures are around 15°-17°C and the relative
humidity 65-85 %. High wind velocity favours spread of powdery mildew.
16. Management
Spray of fungicides (Sulphur based fungicides)
removal and burning of affected leaves, blossoms, twigs
Use of resistant or Best variety
21. Epidemiology
60% diseased pedicles in Feb – March
While same plant has 4.5% malformation in June
Severe when temp. lies b/w 10-15ºC
Observed more in Young Plants
About 91% in 4-8 Years old Plants
22. Disease Cycle
Natural Spread
Aerial Flights
Fusarium Spores
Disease is sporadic in Nature
Propagation & Distribution of diseased
Plants.
May Cause wide distribution of the Disease.
24. Stem End Rot
Reference Books:
Diseases of Fruit Crops
By R.S. Singh
Pg#157
25. Casual Organism
Caused by several fungi but the following is most common
Lasiodiplodia theobromae
Diplodia natalensis
26. Symptomology
The skin of the fruit around the pedicel becomes dark green and water-soaked and
then turns into a brown black circular lesion, surrounded by lighter margin.
This lesion may bear pycnidia of the fungus.
27. Economic Importance
most destructive postharvest diseases
affect tropical and sub-tropical fruits
The fungus can attack mango leaves, twigs and flowers
28. Disease Cycle
Lasiodiplodia theobromae is often considered a disease agent of stressed or
weakened plants. It has a wide host range that includes fruit trees as well as certain
field crops and causes leaf spots, cankers, root rot, fruit rot and seed decay on
different hosts
The fungus survives on the trees in cankers or in the bark or dead twigs and also
through pycnidia On fallen diseased plant parts
Lasiodiplodia theobromae invades mango pedicel through wounds and in mature
green and ripe fruits, the invasion can occur without quiescence
These fungi are present in soil on the orchard floor.
29. Management
Spray of Fungicides
Fruit should be Harvested with minimum 10mm Stalk
Fruits placed in cellophane bags immediately after harvest
Proper Handling can minimize the disease
30. Sudden Death
Reference Books:
Diseases of Fruits & Vegetables
Volume 1
By S.A.M.H Naqvi
Pg#525
32. Economic Importance
Very Destructive Disease in Pakistan
This syndrome is a complex problem
This is the result of a particular mix of fungi resulting in Die back, root rot, tip
dieback, gummosis and dying of trees
Collapse of mango plants occurs within a couple of days because of its quick
decline.
This disease has 100% mortality.
33. Symptomology
First sign of the disease is the oozing of the bark
development of cankers on the trunk
Rotting and blackening of the bark
The splitting of the trunk, and the drying and curling of twigs and branches. Finally,
the leaves are shed from the tree.
Collapse of mango plants occurs within a couple of days because of its quick
decline.
This disease has 100% mortality.
34.
35. Epidemiology:
Artificial inoculation experiments have shown that establishment of fungus requires
at least 48 hrs at temperature 20-32°C and relative humidity of about 80-85%.
36. Disease cycle
The disease can remain in dead trees for a long time, and enters the tree via cuts
and injuries made by unclean equipment, bark beetles and other mango tree bark
feeding insects.
37. Management
Keeping trees healthy and avoiding water stress will help to prevent the trees from
succumbing to the disease
Regular monitoring of orchards is important in identifying the problem at an early stage
Application of Bordeaux mixture twice a year helps to reduce the fungal inoculums
(sources) on the tree
The diseased trees should be removed and burnt
Control bark beetles or caterpillar borers by applying bifenthrin
(e.g. Talstar)
First spray during the last week of February
Second spray before the onset of monsoon rains
Third spray after the rainy season
