Mango Malformation Disease (MMD)

Mango Malformation

    Mango Malformation Disease is a fungal disease of mangoes caused by several species of Fusarium, some yet to be described. Mango is only known host of the disease.
    The disease spreads on a tree very slowly, but if left unchecked, can severely reduce yields. The main method of spreading MMD to new areas is through infected vegetative planting material. There is no evidence that the disease can spread on fruit or the seeds, or that it affects human health. It usually associated with the bud mite, Aceria mangiferae but the mites have been shown to spread the disease within a tree and not
    between trees.
    Mango malformation, also known as bunchy top, is a very serious threat to the mango industry, particularly in northern India. The etiology of the disease still remains obscure and diverse claims have been made about its causes, e.g., physiological, viral, fungal, acarological and nutritional.
    Symptomatology

    Three distinct types of symptoms are produced
    1. Bunchy top of seedlings (BT)
    2. Vegetative malformation (MV)
    3. Floral mal formation (MF)

    Bunchy top of seedlings (BT)
    • Bunchy top phase (BT) appears on young plants in the nursery beds when they are 4-5 months old.
    • Formation of a bunch of thickened small shoot lets bearing small rudimentary leaves or occasionally several bunches arising from a leaf axil at the top or lower down the main shoot.
    • These shoot lets are much thicker than main axis from which they arise. The shoot remains short and stunted.
    • The growth of the plant is stopped and it gives an appearance of bunchy top.

    Vegetative malformation
    • Induces short internodes forming bunches of various sizes. They are found at the top of the seedling and give a bunchy top appearance.

    Floral mal formation (MF)
    • Variation in the panicle formation, the malformed heads dry up in black masses and persist on the tree for a long time.
    • And the secondary branches are transformed into vegetative buds and large number of small leaves and stems, which are characterized by appreciably reduced internodes and are compacted together giving a witches ‘broom appearance.
    • In other cases, the flower buds seldom open and remain dull green

    Malformation

      Etiology
       
      • Fusarium moniliformae var.subglutinans. Wollenw. &Reink. Micro conidia are one or two-celled, oval to fusiform and produced from polyphialides.
      • Macro conidia are rarely produced and are 2-3 celled and falcate.
      • Asexual fruiting body of the fungus is sporodochium.
      • Chlamydospores are not produced.
      Mode of spread and survival
      • Diseased propagated materials help in the spread of the disease.
      Epidemiology
      • The disease is serious before flowering in the northwest region where the temperature is between 10-15oc during December-January.
      • The disease is mild in the areas where temperature is between 15-20oc, sporadic between 20-25o c and nil beyond 25o c. the occurrence of malformation differed according to the age of the plants. 4-8 years old trees are highly susceptible.
      Management
       
        • Spraying with NAA at 100-200 ppm during October reduces the disease incidence.
        • Eradication of malformed shoots and panicles after spring and autumn flushes (April and October),
        • spraying with acaracide (phosphomidon 0.05%) immediately after 3 flushing (February, May and October),
        • Spraying with chelated copper (40 ppm) (mangiferin chelate or amino acid based chelate or copper fungicide) twice (August-September and December –January) before advent of the peak period of the fungal population,
        • Spraying with chelated Zn++ twice (40 ppm) (December and February) to replenish the deficiency in the plants suffering long from the disease.
        • In in vitro test mangiferin Cu++ chelate killed the conidia and mycelia,
        • Aspergillus niger parasitized the Fusarium
        • While carbendazim arrested germ tube growth and reduced conidia production thus affected infection rate (r) of F. moniliforme var. subglutinans.
        • Followed by spraying of Carbendazim 0.1% or captafol 0.2% effectively controlled the disease.

Last modified: Saturday, 14 January 2012, 5:38 AM