1.    Life cycle of wheat stem rust – Puccinia graminis tritici

   Domain – Eukarya

    Kingdom – Fungi

    Phylum – Pucciniomycota

    Sub phylum - Pucciniomycotinia

    Class – Puccniomycetes          

    Order – Pucciniales

    Family – Pucciniaceae

    Genus – Puccinia

                            Species – graminis

 

Stage	spores	Colour	Appearance
O	Pycniospores	Hyaline	Upper
I	Aeciospores	Yellow	Lower
II	Uredospores	Golden brown	Primary host
III	Teliospores	Black	Primary host
IV	Basidiospores	Hyaline	Soil debris

 

Symptoms – Red colour rust pustules appears in stem and leaves. Alternate host is Barberry

Life cycle – When wheat crop attains maturity the uredinia appears on rut pustules and developed as urediniospores, these are single celled, which contains enormous amount of food reserves for long distance dissemination, at the end  of the wheat season it starts to produce less urediniospores and more teiospores.

     Telia are black, elongated, bi-celled, dark brown in colour, it is a resting spore which represents sexual apparatus of the fungus in which karyogamy ad meiosis takes place, when favourable conditions occurs its germinate and produce basidispores of opposite mating types

     Basidiospores infect barberry but not wheat, several basidiospores produce flask shaped pycnium. Several pycnia of opposite mating types are generally formed in the same leaf. On the corresponding to the lower surface it produce aecia

     Aeciospores it contains reserve food material, the aeciopsores can’t germinate on berberry and germinate on wheat leaf.

 

Types of teliospores –

 

Types of teliospore	Example
Single celled  teliospore	Uromyces
Double celled teliospore	Puccinia
Multicelled teliopsore	Phragmidium
Durnip shaped uredospore	Hemileia
Kidney shaped teliospore
Crust like telispore	Melampsora
Parachute like teliospore	Ravenelia

 

 

 

             

Types of rust

Ø  Autoecious rust – Completes its entire life cycle in a single host

Ø  Heteroecious rust  - Requires genetically two hosts to complete their life cycle

Ø  Autoecious macrocyclic rust – Eg – B – Bean rust

                                                            F – Flax rust

                                                            S - Sunflower rust

                                                            S - Safflower rust

Ø  Autoecious demicyclic rust – Eg – Rubus orange rust – Gymnoconia peckiana

Ø  Heteroecious macrocyclic – Eg – Wheat stem rust – Puccinia graminis tritici

            White pine blister blight – Cronartium rubicola

Ø  Heteroecious demicyclic – Eg – Cedar apple rust – Gymnosporangium juniperi

                                                                                                Viriginianae

 

 

2.    Sugarcane ratton stunting

Caused by - Leifsonia xyli subsp. xyli (old name – Clavibacter xyli subsp. xyli), aerobic bacterium.

Symptoms:  

·       The affected plants are stunted, the stunting being most severe in stubble and ratoon crops.

·       In infected stocks, the presence of pin head like orange coloured dots of bacteria on the internal soft tissue in the nodal region

·       The setts taken from diseased plants germinate poorly and the few shoots that are emerged grow very slowly.

Spread – Spread through infected setts

Management strategies

·       Select healthy setts for planting.

·       Field should maintain at proper sanitation.

·       Treat the setts with hot water at 50°C for about 2 hours this gives 100 per cent control.

                     

3.    Tikka leaf spots of ground nuts

Tikka disease: Cercospora arachidicola (early tikkaleaf spot) & Cercospora personata (late tikka leaf spot)

Symptom:

• Early tikka leaf spot: Seen within 3-4 weeks of sowing. On the leaves irregular to circular reddish brown/ black lesions surrounded by “yellow halo”
• Late tikka leaf spot: seen within 5-7 weeks of sowing. Mostly on the leaf margin, enlarged black lesion without yellow halo.

Management:

• Foliar spray with chlorothalonil -0.25%.

                 

4.    Diseases of mango

1. Malformation – Fusarium moniliforme var. subglutinans

·       Symptoms – Vegetative malformation – Bunchy top symptom

·       Floral malformation – produce huge number of flowers gives bushy appearance

·       It is also known as “bunchy top”. Serious threat to mango growing tract of the world. Especially in North India Industries were being threatened. First report in 1891 by Maries from Darbhanga, Bihar. More percent trees are affected in North India.

·       Management –

                                          i.         Diseased plants should be destroyed

                                         ii.         Use of disease free planting material

                                       iii.         Incidence reduced by spraying 100-200ppm NAA during October.

                                       iv.         Pruning of diseased parts along the basal 15-20 cm apparently healthy portions

                                         v.         This is followed by the spraying of Carbendazim (0.1%) or Captafol (0.2%).

2. Powdery mildew – Oidium mangiferae

·       Symptoms – White powdery growth on leaves, Tender shoots, floral parts, Fruits.

ü  Secondary spread by air borne conidia

ü  Warm temperature with heavy morning dew and cloudy weather favour the disease development

ü  3-4 days 24 - 30⁰C min. and max. temp. with 73-83% min. and max. RH.

·       Management

ü  Dusting the plants with fine sulphur (250-300 mesh) @0.5kg/tree or foliar spray with wettable sulphur (0.2%) or karathane/Tridemorph/Carbendazim/hexaconazole/difenconazole (0.1%) can be effectively reduce the incidence.

3. Anthracnose – Gloeosporium gloeosporioides

Symptoms – Leaf spot – Circular, Reddish brown spot on leaf surface

          Die back – Dieing of twigs from tip to downwards

          Floral blight – blackening of floral axis

          Fruit – Irregular black lesion o fruit leads to rotting

4. DIE-BACK: Lasiodiplodia theobromae  (Botryodiplodia theobromae)

Symptoms:

·       The term “die back” implies death of a plant from top to downwards

·       Symptoms can be seen at any time of year but most conspicuous during October and November

·       Dying back of twigs from top down wards and drying of leaves particularly of old trees followed by complete defoliation which gives appearance of “Fire scorch”

·       Management -

ü  Systemic fungicide like Carbendazim, Thiophanate-methyl, Chlorothalonil, difenconazole, carboxamide are recommended generally, but the reality is very difficult to control the disease and save the tree

5. BACTERIAL CANKER : Xanthomoanas campestris pv. mangiferae indicae

Symptoms

·       Small water- soaked lesions appear in groups on surface of leaves. Turn brown to black and get surrounded by yellow halo.

·       Later lesions were often rough and raised. On fruits also same symptom and show cracks in the skin and drop premature. Water soaked spots which turn into cankers on fruits, leaves, petioles, twigs and branches. Hence, they renamed the disease as bacterial canker.

     RED RUST:  Cephaleuros virescens -  Algae

·       Symptoms : Rusty red pustules of the algae on surface of  leaves, veins, petioles and young twigs. First spots are greenish gray – converts to reddish brown. Spots are circular to irregular in shape.

 

Other diseases in mango

1. Sooty mould – Capnodium ramosum
2. Grey blight – Pestalotiopsis mangiferae
3. Red rust – Cephaleuros virescens
4. Bacterial canker – Xanthomonas campestris pv. mangiferae-indica
5. Giant mistletoe – Dendropthe sp. (Loranthus)

 

Classification of powdery mildews

PHYLUM: Ascomycota

CLASS: Filamentous ascomycetes

ORDER: Ersiphales (the powdery mildew fungi) Asci in fruiting bodies completely closed (cleistothecia). Myceliun, conidia and cleistothecia on surface of plant. Obligate parasites.

The following are some of the main genera of powdery Mildews and some of the important diseases they cause.

GENUS:

·       Blumeria; cereals and grasses

·       Erysiphe; Herbaceous plants. Begonia, chrysanthemum, Cucurbits, dahlia, zinnia, legumes, beets, crucifers, tomato.

·       Leveillula; Tomato Microsphaera; Azalea, rhododendron, lilac,

·       Oidium; (anamorph only) tomato, begonia.

·       Phyllactinia sp; Shade and forest trees.

·       Podosphaera; Apple (P. leucotricha), quince, apricot, cherry, Peach, plum, cucurbits.

·       Sphaerotheca; strawberry, gooseberry, currant, peach, rose.

·      Uncinula; Grape (U. necator).

              

Types of powdery mildew

The powdery mildew fungi are characterised based on the type of mycelium and conidiogenesis, these are 3 types, Oidium, Oidiopsis, Ovulariopsis

Category	Oidium	Oidiopsis	Ovlariopsis
Mycelium	Hyaline, septate and ectophytic	Hyaline, septate and endophytic	Hyaline, septate, ecto and endophytic
Haustoria	Present in epidermis only	Present in epidermis and spongy cells only	Epidermal haustoria absent
Conidiophore	Short club shaped, non septate	Long branched and septate	Branched, septate
Conida	Cylindrical or barrel shaped in chains	Single celled, club shaped	Single celled, clavate or club shaped
Clestothecia	Myceliod appendages	Myceliod appendages	bulbous appendages
Host (species can produce this type)	Erysiphe	Leveillula	Phyllactinia