Lecture - 20 Etiology and control of Mosaic of Tomato and Tobacco, Yellow Vein Mosaic of Bhindi and Bunchy top of Banana
Tomato Mosaic Virus:-
Pathogen:-
> Tomato mosaic virus (ToMV) is a member of family tobamoviridae and belongs to the genus tobamovirus, which is a plant pathogenic virus.
> It is found worldwide and affects tomatoes and many other wide host range plants including many agricultural crops and weeds such as tobacco and beans, all of which can serve as inoculum sources.
> The tomato crop is highly susceptible to the Tomato mosaic virus (ToMV).
> The symptoms vary from tiles, wrinkle, reduction and curvature of leaflets, and irregular ripening of fruits.
> This disease requires attention because of its easy dissemination by contact, cultural practices, or contaminated seed.
Symptoms:-
> Tomato mosaic virus symptoms can be found at any stage of growth and all parts of the plant may be infected.
> ToMV causes yellow mosaic symptoms on the leaves and tomato fruits.
> Tomato mosaic virus symptoms are seen as a general mottling or mosaic appearance on foliage.
> Light and darker green mosaic leaf mottle, sometimes with distortion of younger leaves; this is the most common reaction in summer in glasshouses.
> In winter, with low light intensity, short days and temperatures not above 20°C, plants are often severely stunted and leaves distorted to ‘fern-leaf’ or tendril shape, but mottling may be slight.
> Plants are less vigorous, and fruit yield is reduced by 3 to 23%.
> Tomato mosaic virus strains occur in Chenopodium murale in the USA, causing severe stunting, distortion and necrosis, and in pear associated with a diffuse chlorotic leaf spotting.
Management:-
> Treating mosaic virus is difficult and there are no chemicl controls like there are for fungal diseases.
> Tomato mosaic virus has been found to survive for up to 50 years in desiccated plant detritus! So tomato mosaic virus control then leans less on eliminating the disease and more on reducing and eliminating the virus sources and insect infestations.
> Control is mainly based on the use of virus-free seeds.
Yellow Vein Mosaic of Bhindi:-
Yellow Vein Mosaic Disease (पीला शिरा मोज़ेक रोग):- Bhindi Yellow vein mosaic virus or Bhindi vein clearing virus.
The virus that causes YVMD, was first identified in India, during 1924 (Kulkarni 1924). Very serious constraint in bhendi production through out the country. BYVMV consists of a monopartite begomovirus associated with alpha- and beta satellite DNA components
[इस रोग के लिए जिम्मेदार वायरस की पहली बार 1924 में भारत में पहचान की गई थी (कुलकर्णी 1924)। यह भिंडी उत्पादन में पूरे देश में एक गंभीर बाधा है। BYVMV एक मोनोपार्टाइट बेगोमोवायरस से बना होता है जो एल्फा और बीटा सैटेलाइट DNA घटकों से जुड़ा होता है।]
Vactor (वाहक):- Bamisia tabaci (White fly) (सफेद मक्खी)
Symptoms (लक्षण):-
- Yellowing of the entire network of veins in the leaf blade (vein clearing) is the characteristic symptom. In severe infections the younger leaves turn yellow, become reduced in size and the plant is highly stunted.
[पत्तियों के फ़लक में शिराओं के पूरे जाल का पीला होना (शिरा साफ होना) इस रोग का विशेष लक्षण है। गंभीर संक्रमण में युवा पत्तियां पीली हो जाती हैं, उनका आकार छोटा हो जाता है और पौधा बौना हो जाता है।]
- In a field, most of the plants may be diseased and the infection may start at any stage of plant growth.
(खेत में, अधिकांश पौधे रोगग्रस्त हो सकते हैं और संक्रमण पौधे की वृद्धि की किसी भी अवस्था में शुरू हो सकता है।)
- Infection restricts flowering and fruits are not formed, if formed, turn smaller, harder and rough. Loss in fruit yield ranges from 50-100% based on disease incidence.
(संक्रमण पुष्पन को रोकता है और फल नहीं बनते हैं, और अगर फल बनते हैं तो वे छोटे, सख्त और खुरदरे होते हैं। फल उत्पादन में हानि रोग की तीव्रता पर निर्भर करते हुए 50-100% तक होती है।)
Survival and spread (जीवितता और फैलाव):-
Primary (प्राथमिक):- Virus particles in infected plants and collateral hosts like Hibiscus tetraphyllus, Croton sparsiflora and Ageratum spp.
(संक्रमित पौधों और सहायक परपोषियों जैसे हिबिस्कस टेट्राफाइलस, क्रोटोन स्पार्सिफ्लोरा और एजिरेटम जाति में वायरस कण।)
Secondary (द्वितीयक):- Virus particles transmitted by whitefly Bemisia tabaci.
(सफेद मक्खी बेमिसिया टैबेकाई द्वारा वायरस कणों का प्रसारण।)
Management (प्रबंधन):-
- Tolerant varieties (सहनशील किस्में):- Parbhani Kranti, Pusa savani, Janardhan, Haritha, Arka Anamika and Arka Abhay.
(परभाणी क्रांति, पूसा सावनी, जनार्दन, हरिता, अर्का अनामिका और अर्का अभय।)
- Removal and destruction of infected volunteer plants and collateral hosts in the vicinity of the field.
(संक्रमित स्वैच्छिक पौधों और सहायक परपोषियों को खेत के आस-पास से निकालना और नष्ट करना।)
- Erection of yellow sticky traps in the field to trap the whiteflies.
(सफेद मक्खियों को फँसाने के लिए खेत में पीले चिपचिपे जाल लगाना।)
- Vector management for restricting spread by spraying systemic insecticides like Monocrotophos, 1.5 ml/l, Dimethoate or Methyl S Demetan 2 ml/l.
(प्रसार को रोकने के लिए वाहक प्रबंधन के रूप में मोनोक्रोटोफॉस 1.5 मिली/लीटर, डाइमेथोएट या मिथाइल एस डेमेटन 2 मिली/लीटर जैसे सिस्टेमिक कीटनाशकों का छिड़काव।)
Bunchy Top of Banana:-
Etiology:-
Causal virus:- Banana Bunchy Top Virus (BBTV)
Family:- Nanoviridae, genus Babuvirus.
Genome:- Multi-component circular single-stranded DNA.
Transmission:- By banana aphid (Pentalonia nigronervosa) in persistent manner.
> No seed/bulb transmission, but carried in infected suckers (vegetative propagation).
Symptoms:-
> Initial dark green streaks on leaf veins, midrib and petiole (“Morse code” symptom).
> Leaves become narrow, short, and stiff.
> Leaves stand upright, crowded at top → “Bunchy top” appearance.
> Plants fail to produce bunches or produce deformed bunches.
> Disease is systemic and incurable once plant is infected.
Control:-
i. Cultural:-
> Use virus-free suckers only.
> Rogue out and destroy infected plants immediately.
> Eradicate alternative host weeds (wild bananas).
ii. Vector Management:-
> Control banana aphid using systemic insecticides like imidacloprid, dimethoate, monocrotophos.
> Maintain weed-free banana fields.
iii. Plant Resistance:-
> Some resistant/tolerant clones available (e.g., Musa balbisiana wild bananas).
iv. Quarantine:-
Strict regulation to prevent spread to new areas through infected suckers
