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Biotic Diseases (cont.)

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Biotic Diseases (cont.) Fungal Diseases (cont.) dr.mohamed.naguib_at_gmail.com – PowerPoint PPT presentation

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Title: Biotic Diseases (cont.)


1
Biotic Diseases (cont.)
  • Fungal Diseases (cont.)

2
Rhizopus
  • The Mycelium consists of branched non septated
    hyphae, which grow creeping upon the substratum,
    called Stolon.
  • Each stolon sends branched rhizoids to the
    substratum for absorption of the necessary food
    material.
  • Opposite to rhizoids , sporangiophores arise ,
    each terminating with numerous spores and sterile
    portion known as columella.

3
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4
Disease
  • Rhizopus soft rot
  • Symptoms
  • The color of the infected tissue turns from
    purple to brown, and a pronounced fermentive odor
    is produced. The odors from affected sweet
    potatoes attract fruit flies, which reproduce in
    the decaying tissue and become abundant in the
    storage area.

5
Aspergillus
  • The mycelium is branched and septated.
  • Conidiophore is unbranched and non
    septated terminates with swollen heads , each of
    which carries radiating stregmata.
  • Chain of conidia arranged in basipetal
    succession

6

A. fumigatus
A. clavatus
7
Disease
  • Aspergillus ear rot
  • Symbtoms
  • Aspergillus niger appears as a black mold on
    infected kernels. A. flavus is a greenish-yellow
    mold growing on damaged kernels. A. glaucus is a
    greenish mold

8
Penicillium
  • Species of Penicillium are recognized by their
    dense brush-like spore-bearing structures.
  • The conidiophores are simple or branched and are
    terminated by clusters of flask-shaped phialides.
    The spores (conidia) are produced in dry chains
    from the tips of the phialides, with the youngest
    spore at the base of the chain, and are nearly
    always green.
  • Branching is an important feature for identifying
    Penicillium species.

conidia
phialides
Conidiophore
9
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10
  • Disease
  • Penicillium stem rot .
  • Symbtoms
  • Infection appears initially as water-soaked,
    translucent areas at the nodes, especially nodes
    that have been pruned. Within a day or so, this
    becomes a pale-brown canker with a blue-gray to
    blue-green fungal growth on the surface giving
    off a cloud of spores

11
Alternaria
  • The mycellium consists of branched and
    septated hyphae.
  • Conidiophores are mostly unbranched and
    septated.
  • Conidia develop at the tips of
    conidiophores.
  • Conidia with transverse and longtudinal
    septa, mostly elongate at the tip, muriform in
    the lower portion , borne usually in simple
    chains.

12
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13
Disease
Early Blight disease Symptoms The disease
appear as , dark, round depressions on the peel
causing dark necrotic concentric lesions
. Initial infestation is by wind-borne conidia
that penetrate through superficial wounds in the
epidermis.
14
Curvularia
  • Composed of branched and septated mycelium.
  • Conidiophores are unbranched and septated .
  • Conidia may be obclavate or cylindrical ,
    usually curved , carried singly on the
    conidiophores.
  • Conidia with 3 or 4 septa , the central cell
    being larger than the terminal cells.

15
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16
Disease
  • Curvularia blight
  • Symptoms
  • Small yellow-brown spots on leaves expand to
    oblong lesions. Center of lesions change to brown
    and margins remain yellow. Lesions are more
    common on leaf margins.

17
Fusarium
  • 1- Mycelium consists of branched septated
    hyphae .
  • 2- Fusarium reproduces asexually by means of 3
    kinds of asexual spores
  • a) Macroconidia long , multicellular and
    crescent-shaped, both ends of macroconidia are
    pointed , cells from which Macroconidia develops
    are called phialides.
  • b)Microconidia are small , usually unicellular
    , spherical or oval bodies.
  • c) Chlamydospores are round or oval thick
    walled , terminal or intercalary vells of the old
    hyphae

Macroconidia
Microconidia
Chlamydospores
18
Macroconidia
Microconidia
Chlamydospoes
19
Disease
  • Fusarium root rot
  • Symptoms
  • The disease initially appears as red to
    reddish-brown lesions on stems and primary root
    2-3 weeks after planting.Affected areas may merge
    and enlarge with age, turn necrotic, and
    gradually extend up from the soil surface.
    Primary and secondary roots are killed in severe
    cases. If moisture is sufficient, lateral roots
    may develop above the initial site of infection,
    which helps plants survive. Infected plants are
    rarely killed and above ground symptoms in the
    field include stunting and yellowing of leaves

20
Reddish-Brown Lesions
Gradually Extend
Merge and Enlarge
Lateral Roots May Develop
21
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22
Cladosporium
  • It is found both indoors and outdoors.
    Colonies range from a dark green to black color.
  • They are relatively slow-growing.
  • The dark spores are normally one to two
    celled and occur in long, branching chains that
    arise from a dark conidiophore.
  • The youngest spores are those found at the
    top of the chain

23
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24
Disease
  • Cladosporium ear rot Cladosporium herbarum and
    other species often infect kernels damaged by
    insects, hail, or frost.
  • Symptoms
  • 1-This fungus appears gray to black or very dark
    green.
  • 2- can have a powdery appearance.
  • 3-It also causes black streaks in the kernels.
  • This disease can be fairly common but usually
    does not cause extensive damage to the ears.

25
Download link 1-http//rapidshare.com/files
/217975739/section_7_cultures.ppt.html
2-http//filegetty.com/278079/
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