DISEASE OF GUAVA | 2 MOST IMPORTANT DISEASE OF GUAVA

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DISEASE OF GUAVA

(DISEASE OF GUAVA – Guava Wilt and Dieback and Anthracnose (fruit rot) – Symptoms, Etiology, Favourable conditions)

in this article, we are going to learn about 2 most important diseases of guava

DISEASE OF GUAVA – GUAVA WILT 

Symptoms Of Guava Wilt :- ( DISEASE OF GUAVA )

  • Loss of turgidity in a branch or branches of one side of the tree is the first external symptom.
  • Leaves in this branch wither turn pale and droop before finally dropping off.
    Symptoms gradually appear on other branches also Infected and withered branches do not recover.
  • A few plants may show partial wilting, which is a common symptom of wilt in guava.
    The finer roots show black streaks which appear prominent on removal of bark.
    The roots also show rotting at the basal region and the bark is easily detachable from the cortex.
  • Light brown discoloration is noticed in vascular bundles.

Causal organism – Fusarium oxysporum sp. psidii

kingdom  Fungi
sub – division Deuteromycotina
class Deuteromycetes
order Moniliales
Family Tuberculariaceae
Genus Fusarium

Etiology:-

Pathogen: Extensive, hyaline, often with some tinge of pink-purple or yellow, septate, inter and intracellular.
Macroconidia (3-8 x 11-70 µm) are produced from phialides on unbranched or branched conidiophores They are 2 or more celled, thick-walled, smooth, and cylindrical or fusiform, sickle-shaped.
Microconidia (2-4 x 4-8 µm) are formed on long or short simple conidiophores. They are 1-celled (occasionally 2 or 3 celled), smooth, hyaline, ovoid to cylindrical, and arranged in balls.
Chlamydospores, when present, in pairs, clumps or chains. They are thick-walled, hyaline, intercalary or terminal .

Favourable conditions For Guava Wilt :-

pH 6.0 is optimum for disease development. Both pH 4.0 and 8.0 reduces the disease.
Disease is more in loamy alluvial soils than in heavy soils
Disease incidence increases in post monsoon period
The nematode, Helicotylenchus dihystera aggravates the disease

Management Guava Wilt :-

Host Plant Resistance

Resistant varieties: Apple guava, banarsi, dholka sind, nasik and Bhuvanagiri. Psidium species, Psidium cattleianum var. lucidum and Syzigium cumini (Jamun) are resistant to wilt

Chemical

Drench the basins of trees in orchards with disease incidence with 0.2% Benomyl or Carbendazim four times in a year
Soil treatment with gypsum and lime(1:1 ratio)
Injecting healthy plant with 0.1% 8-quinolinol sulphate will minimize the disease.

Dieback and Anthracnose (fruit rot)

Symptoms Dieback and Anthracnose :-

Die back phase:
Young shoots, leaves and fruits are readily attached, while they are still tender.
The greenish colour of the growing tip is changed to dark brown and later to black necrotic areas extending backwards.

Fruit and leaf infection phase:
Pin-head spots are first seen on unripe fruits, which gradually enlarge.
Spots are dark brown in colour, sunken, circular and have minute black stromata in the center of the lesion, which produce creamy spore masses in moist weather.
The infected area on unripe fruits become corky and hardy and often develops cracks in case of severe infection.

causal organism :- Colletotrichium psidii

Kingdom             –  Fungi
Sub-division        –  Deuteromycotina
Form Class         –  Deuteromycetes
Form Sub class   –  Coelomycetidae
Form Order         –  Melanconiales
Form Family        –  Melanconiaceae

Etiology :-

Mycelium – Septate, hyaline, inter and intra cellular, branched.
Acervuli – Acervuli develop beneath the cuticle. Cushion shaped, provided with short conidiophores and sterile setae.
Setae – Straight, un-branched, tapered towards the apex, brown to black, smooth, thick walled and septate.
Conidiophore – Hyaline to brown, septate, branched at the base, smooth, short, packed in acervuli.
Conidia – Falcate (sickle shaped), posses large oil globule in centre, hyaline, unicellular, borne singly on tip of short conidiophores.

Survival and spread Of Dieback and Anthracnose :-

Infection spreads by wind borne spores develop on dead leaves, twigs and mummified fruits in the orchard.

Dense canopy is congenial for germination of spores due to high moisture condition

Movement of planting material through infected foliage

Transportation of fruits from high disease prone area

Favourable conditions Dieback and Anthracnose :-

> Closer planting without canopy management

The acervul with pink spore masses are produced in moist weather on dead twig and mumified Fruits
Dew or rains encourages spore production and its dispersal around canopy.
Temperature between 10 to 35°C with best 24 to 28 C.

Management Of Dieback and Anthracnose :-

Three applications of Bordeaux mixture and Perenox (0.22 and 0.33%) after removal of dead twigs.

Spray of copper oxychloride and cuperous oxide (3%rat weekly intervals effectively reduce the infection.

Apply Carbendazim Igm/litre during June-September.

10 COMMENTS

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