AgMOOCs  Assignment on Use Social Networks to find solutions

Based on the suggestions received from my friends( facebook), I concluded that the picture shows early blight in tomato. 

Detailed Report on

Early Blight or Alternaria Leaf Spot 

PATHOGEN: Alternaria solani

SYMPTOMS:

Foliar symptoms generally occur on the oldest leaves and start as small, brownish to black lesions. These leaf spots enlarge up to ½ inch (1.3 cm) in diameter in a characteristically concentric fashion. The area around the spot may become yellow, as may entire severely affected leaves. Under favorable conditions, significant defoliation of lower leaves may occur, leading to sunscald of fruit.

Green or red fruit may be infected by the fungus which invades at the point of attachment between the stem and fruit, and through growth cracks and wounds made by insects. Dark lesions enlarge in a concentric fashion and may affect large areas of the fruit. Mature lesions in fruit are typically covered by a black velvety mass of fungal spores. Stem lesions are dark, slightly sunken and enlarge concentrically. Basal girdling and death of seedlings may occur.

DISEASE CYCLE & EPIDEMIOLOGY:

Alternaria solani overwinters primarily on infected crop debris. The dark pigmentation of the mycelium increases resistance to lysis which extends the survival time in the soil to several years. Thick-walled chlamydospores have been reported, but they are found infrequently. In mild climates the pathogen can survive from season to season on volunteer tomato and potato plants as well as other weedy Solanaceous hosts such as horsenettle and nightshade.

Warm, humid (24-29°C/ 75-84°F) environmental conditions are conducive to infection. In the presence of free moisture and at an optimum of 28-30°C (82-86°F), conidia will germinate in approximately 40 min. Desiccated germ tubes are able to renew growth when re-wetted, and, hence, infection can occur under conditions of alternating wet and dry periods. Germ tubes penetrate the leaf epidermis directly or enter through stomata. Infection of potato tubers usually occurs through wounds in the tuber skin inflicted during harvest. Wet conditions at harvest provide a favorable environment for spore germination as well as causing swollen lenticels on the tubers which are easily invaded.

Time from initial infection to appearance of foliar symptoms is dependent on environmental conditions, leaf age, and cultivar susceptibility. Early blight is principally a disease of aging plant tissue. Lesions generally appear quickly under warm, moist conditions on older foliage and are usually visible within 5-7 days after infection.   A long wet period is required for sporulation but it can also occur under conditions of alternating wet and dry periods.  Conidiophores are produced during wet nights and  the following day light and dryness induce them to produce spores, which emerge on the second wet night.  Secondary spread of the disease results from conidia being dispersed mainly be wind and occasionally by splashing rain or overhead irrigation.  Early blight is considered polycyclic with repeating cycles of new infection.  This is the period when the disease has the potential to spread rapidly and build up to damaging levels in the crop.

CONTROL MEASURES

Cultural Controls:  

1.    Use pathogen-free seed and transplants.

2.  Maintain plant vigor through adequate irrigation and fertilization to increase disease resistance.

3.    Avoid plant injury which allows entry of the pathogen and spread of the fungus through adequate insect management

4. Remove and destroy crop residue at the end of the season. Where this is not practical, plow residue into the soil to promote breakdown by soil microorganisms and to physically remove the spore source from the soil surface.

5.  Practice crop rotation to non-susceptible crops (3 years). Be sure to control volunteers and susceptible weeds.

6.    Promote good air circulation by proper spacing of plants.

7.    Orient rows in the direction of prevailing winds, avoid shaded areas, and avoid wind barriers.

8.    Hand picking diseased foliage may slow the rate of disease spread but should not be relied on for control. Do not work in a wet garden.

9.    Use resistant or tolerant varieties.

Chemical control:

1. The preventative fungicide chlorothalonil (Bravo) used on a seven to ten day schedule gives effective control.
2. Using a good broad spectrum fungicide, such as GreenCure and spraying every 2 weeks during periods of optimum conditions for the Early Blight disease.

Application of Cyber extension /ICT tools in transfer of technology

ICT tools	Uses in Agricultural Extension
1. Interactive video	Information delivery, education, farmers problem solving.
2. Audio conferencing	Training, Institutional out reach and administrating extension services.
3. Multimedia	Training, Information delivery
4. Internet	Information can be made available to the farmers round the clock.
5. Expert system	Decision making, designing, selection, diagnosis and prediction.
6. Agri portal	Instant information on markets, news and weather.
7. E mail, Mobile phone	Providing information at the right time
8. website	Latest farming oriented news and information.

ADVANTAGES OF CYBER EXTENSION

• Saves money, time and effort: scientists will prepare electronic version of messages themselves. These versions don’t have to be printed and posted. This will save money and time. Cyber messages will be updated online and that saves time too. Cyber extension can provided more in-depth analysis and can also provide detailed on-farm research results to the curious users / farmers.
• Cuts steps from extension process: Cyber Extension will remove a number of steps altogether from the traditional extension process. In the context of Agriculture, the zonal workshops and training to subject matter specialists (SMS) can be eliminated altogether. The scientists can directly post the information on the Internet, which will be directly available to extension functionaries at district, sub division, block and village level. All the concerned will get the information immediately and queries / clarifications will also be addressed equally fast, without involving a chain of extension machinery. In the context of Rural Development the details of Central and State sponsored schemes can be directly communicated to the ultimate user/ beneficiary. The lists of Below Poverty Line (BPL) can be made available to all the agencies like Regional Rural Banks, DRDAs and list of beneficiaries under one programme can be made available to other implementing agencies, to avoid duplication of efforts in same direction.
• Information rich and interactive: It appeals to the curious extension workers and analytical farmers. It will allow them to search and locate the information they need quickly. The extension workers can talk to the concerned scientists for more information on the subject, wherever the scientists may be. The rural technologies can be made available on CD-ROMs for quicker dissemination.
• Offering instant international reach: Online networks have created an instant global village. Cyber extension will eliminate the time and distance barrier that get in the way of knowing the latest information on any particular problem from any part of the world. One can reach any university, National, state level training and research institutions and other research station and discuss his / her problems with the best scientists / experts in the field.
• Continuously available: One of the key attributes of an online information service is that it is available all the time, 24 hours a day, 365 days a year. Your cyber extension functionary doesn’t sleep; he doesn’t go on leave. If you have connectivity, you can get information, from wherever it is available.

LIMITATIONS OF CYBER EXTENSION

• Cyber extension is becoming an tool for development communication, however most rural   communities are not yet able to take advantage of this new tool due to illiteracy, lack of skills,  economic power.
• There will be both irrelevant and relevant messages Cyber extension is more expensive.
• It cut steps from extension process like training and zonal workshops.
•  Not all messages will be suitable to all farmers.
  

Cyber Extension: Information is an important resource in modern agriculture. The development of computers and improvements in telecommunication offers farmers and extension workers, many new opportunities to obtain technical and economic information quickly and use it effectively for their decision making.

Cyber: According to Oxford Dictionary the word Cyber means, “relating to Information Technology, the Internet, and virtual reality, the Cyber Space”

The Cyber Space: Cyber Space is the imaginary or Virtual space of computers connected with each other on Networks, across the globe. These computers can access information in the form of Text, Graphics, audio, video and animation files. Software tools on networks provide facilities to interactively access the information from connected servers. The cyber space thus can be defined as the imaginary space behind the interconnected telecommunications and computer networks, the virtual world.

Cyber Extension: Cyber Extension thus can be defined as the “Extension over Cyber Space” or ‘Extension over virtual space’. As the word Extension is subject-neutral, so is Cyber Extension. But in the applied context of Agriculture, Cyber Extension means “using the power of online networks, computer communications and digital interactive multimedia to facilitate dissemination of agricultural technology”.

Cyber Extension means, "Using the power of online networks, computer communications and digital interactive multimedia to facilitate dissemination of agricultural technology".

Cyber Extension includes effective use of Information and Communication technology, national and international information Networks, Internet, Expert Systems, Multimedia Learning Systems and Computer based training systems to improve information access to the Farmers, Extension Workers, Research Scientists and Extension Managers.