documents/14-Diseases-of-Jute.txt

Diseases of Jute
Fungal diseases
Anthracnose Colletotrichum corchori
Stem rot Macrophomina phaseolina
Black band Botryodiplodia theobromae
Leaf spot Cercospora corchori
Target spot Corynespora cassiicola
Bacterial diseases
Bacterial leaf blight Xanthomonas campestris pv. capsularii
Nemic diseases
Root-knot Meloidogyne incognita
Viral diseases
Mosaic Jute mosaic virus
Stem rot
Causal Organism: Macrophomina phaseolina
Symptoms:
This disease appear from seedling to maturity. In seedling stage blackish streak developed from the
hypocotyl. In moist condition damping off occur at the seedling stage. In mature plants leaves are
infected buff to black color lesions are developed at the apex, in margin, midrib and also petiole.
After progress of the disease that dark brown to black lesions developed at the nodal region. This
lesion spread along the stem. Cortex become shredded and exposed the fibers. The later stage of
disease, the plant sheds leaves, stem rots and ultimately die. Then the capsules and seeds are also
infected. Numerous black sclerotia and frequently subcarbonaceous pycnidia developed on diseased
parts. Only dark black stem remains in the field.

Disease cycle:

Disease cycle of stem rot of jute
The pathogen perpetuates on stubbles and in soil in the jute fields in its sclerotia form. It also
harbours on the jute seeds under the seed coat and within the cotyledons. Where rotations are
practiced, other crops like linseed, sesame or cowpea may form the collateral hosts. The pathogen
has also been found to survive on a common weed Cyperus distans.
But primary infection is chiefly due to the seed borne inoculum than any other source. There are
two phases of disease development. During the first phase the pathogen kills a large number of
seedlings and young plants in the first two months. During the second phase, which starts after the
plants are four to five months old, there are no deaths, but quality of the fiber is ruined owing to the
formation of cankers and shredding.
Due to primary infection, symptoms appear in the seedlings on the cotyledonary leaves and the
hypocotyl within a fortnight after sowing leading to the development of pycnidia. Conidia released
from the pycnidia of the diseased seedlings cause secondary infection on the leaves in the vicinity
of the seedlings where primary infection has been established. Both rain and air play a great role
for dispersal of conidia. The conidia readily infect the leaves and the leaf infection spreads to the
node through the petiole. In an infected stem, the pathogen grows in the epidermis and cortex, often
invading the phloem parenchyma and the wide rays between the phloem wedges. It is also found in
the central woody portion, the hyphae penetrating even the wood fibers.
Ultimately girdling of the stem occurs causing rot of the stem which leads to either shredding,
canker or wilting. Usually the secondary infection is four times the primary infection. Prolonged
warm and humid conditions favour disease development leading to the severe outbreak of the stem-
rot. Initially abundant leaf infection is visible during and after heavy rains which gradually leads to
the spread of the disease. The most critical period for the crop is first eight weeks of its growth, for
it is during this period that the disease is serious.
Again if the weather during this period is comparatively dry, the incidence of the disease is less.
The interval between the appearance of the stem-rot and the death of the plant ranges between one
and twenty weeks. Where the top of the plant is attacked the death is quicker. Attacked plants often
survive by means of callus formation. Root-rot usually occurs sporadically late in the season, but
also appears early in the season when high temperature prevails.

Control measures
(i) Use clean seeds from localities where disease incidence has not been reported.
(ii) Seeds should be thoroughly dried and before storage should be treated with Organomercuric
compounds.
(iii) Betterment of cultural practice in the following manner
(a) Improvement of soil pH with lime
(b) Application of potash between 50 to 100 Kg/ha in soil
(c) Good drainage and improvement of porosity (in clay soil) with organic matter
(d) Proper spacing 30 cm. x 7 cm., weeding, and thinning
(e) Crop rotation jute with paddy.
(iv) Spraying copper oxychloride (50% Cu) at 0.75 concentration at first leaf infection produces
fruitful results. Leaf infection can be reduced spraying 0.2% Lime Sulphur and Bordeaux mixture
(5:5:40) under field condition.
(v) Early harvesting reduces loss of fiber.
(vi) Since the fungus can survive on linseed, sesame and cowpea, these plants should not be grown
in jute fields.
(vii) Jute field weed Cyperus distans should be eradicated to reduce the source of inoculum.
(viii) Root-rot can be effectively controlled by the use of Brassicol
Black band
Causal Organism: Botryodiplodia theobromae
Symptoms:
A dense black band develops around the stem of the mature plant at about 2-3 feet above the ground
level. The bark of the stem in some places splits open longitudinally with exposed, brownish dry
fibers at the later stages of disease development and die. Large number of minute black pycnidia is
formed on the affected blackened area of the stem. On rubbing the diseased stem, fingers become
black due to dark pycnidiospores.
Control measures


Anthracnose
Causal Organism: Colletotrichum corchori
Symptoms:
The disease first appears as yellowish-brown, depressed water soaked spots on the stem, which
soon turn into irregular lesions and may become dark brown and finally black. In most cases the
lesions are elongated having tapering ends and wide at the middle giving spindle or eye shape
appearance. The lesion develops cracks in the center and the fibers are exposed. Sometimes
several spots may coalesce and produce large cankerous lesions and in many cases they girdle the
stem. The fungus also infect the vascular bundle of the plants. The black dot like acervuli are seen
on the surface of the affected area. Affected seedlings die and mature plants may wilt or survive to
produce poor quality pods and seeds. The capsule and seeds are also infected.
Disease cycle:
The planting materials may harbour the fungus and thus perpetuate the disease from season to
season. The fungus may also persist in the soil if diseased stubble and dry leaves left in the field
after harvest. The primary infection, however, appears to be mainly from infected seeds. Secondary
infection takes place by the conidia produced on the affected stems. Secondary spread in the field
may be through irrigation water, cultivation tools and implements and wind-borne inocula. The
fungus also survives on collateral hosts Sorghum vulgare, S. halepense, and Saccharum
spontaneum.
Control measures:

• Crop rotation with rice, wheat etc.

Dieback: Mature plants are susceptible to the dieback disease, caused by Diplodia corchori. The
apex of the main stem or branches begins to wither and dry up progressively from tip downwards
turning brown to black. Ultimately, the plant withers, leaves drop off. Lack of requisite moisture in
soil and low fertility favour the disease. It is most prevalent in the red soil areas. Spraying Copper

recommended for control.
Soft rot: The disease is caused by Sclerotium rolfsii. The fungus is soil borne. The disease initiates
infection in late July onwards when the plants become older. Soft, brown, wet patches appear on
the basal region of the plant above the ground level. Epidermal layer peels off exposing the fibers
turning rusty brown. Eventually plant breaks off from the point of infection. Concentric ring of light
and dark brown bands on the stem indicate the presence of soft rot. The fungus thrives on fallen
jute leaves or plant of previous harvest. Deep ploughing and clean cultivation along with spraying
Copper oxychloride (50 per cent Cu) helps to control the disease.
Nematodes (Meloidogyne incognita) – The infestation is more in sandy loam and loamy soil where
repeated jute cultivation is practiced. Nematodes affected the root and as a result gall are formed.
In association with soil fungi, they affect the plants. As a result leaves first get yellow and gradually
the plants wither away. Heavy gall formation is early stages of growth leads to arrest of growth of
the crop. During crop season the infestation starts. Applying Carbofuran 3 kg a. i./ha or Aldicarb
3kg a.i./ha may control the pest.