Breakthrough in apple defoliation disease
by Ambika Sharma

THE prevalence of a unique disease in apple has disrupted the future prospect of successful apple cultivation in Himachal Pradesh. Apple plantations in this hill state have been ravaged by a unique phenomenon of leaf shedding in mid-summer for the past two years. The problem starts in the month of June-July and by mid-August all the orchards in the state are found affected and only fruits nearing maturity are seen hanging from the defoliated branches. The disease, which was first detected in the 1995 season in some orchards has now spread to all apple orchards in the state and is now affecting more than 90 per cent of orchards. All the commercial delicious cultivars are susceptible. Premature leaf shedding in apple is also reported recently from Kashmir, neighbouring UP hills and Bhutan.

Extensive studies in the Scab Monitoring and Research Laboratory located at Kotkhai in the past three seasons conclusively proved that a fungal disease marssonina blotch is soley responsible for causing premature defoliation of apple. This problem is more severe in shady areas and the orchards receiving regular anti-scab spray of fungicides are less attacked. The casual fungus has been isolated in pure culture and deposited in the famous repositories in India and abroad. The pathogenicity was also proved in semi-controlled conditions. The pioneering work undertaken at the Dr Y.S. Parmar University of Horticulture and Forestry by Dr J.N. Sharma has led to its proper diagnosis and control in the field. Marrssonina blotch, first observed in Japanese orchards in 1904, was not important in Himachal Pradesh till recently when it caused premature leaf fall of apple. It is also reported from Canada, Romania, China and Korea. This affects the fruit size, colour and quality adversely. Appearance of fruit spots on the produce makes it unsaleable in the market. It also reduces the fruit set in the following season.

Disease symptoms first appear as dark green circular patches on upper surface on the mature whorl leaves giving rise to 5 to 10 mm diameter brown leaf spots which turn dark brown in the due courses. When lesions are numerous they coalesce to format larger dark brown blotches and the surrounding areas turn yellow.

Severe leaf shedding follows these symptoms. In affected orchards, apple fruits nearing maturity are commonly seen hanging from the defoliated branches and so disease is accordingly called premature leaf fall. Symptoms also appear on the fruit in the format of clear brown spots, which are initially circular (3 to 5 m in diameter) and become oval, depressed and dark brown later. Numerous small black colour pinhead specks, the acervuli are visible in the affected tissues. This disease is caused by marssonina coronaria Syb: M.mali with diplocarpon

mali as its perfect state. This fungus is reported to perennate in the fallen leaf litter on the orchard floor. The seeds of the fungus are mature by the time of blooming in apple in the spring and they are liberated in the orchard for a quite long period. Frequent rains are helpful for disease development. Infections first appear on mature whorl leaves turning yellow and fall prematurely. Countless conidia microconidia are formed on diseased leaves with again cause fresh infections leading to epidemic development in highly favourable conditions.

The disease can be controlled by integrating different methods like field sanitation, proper pruning and judicious use of fungicides. The orchardists are advised to collect and destroy the fallen leaves from the orchard floor in winter. Urea (5 per cent) spray on the leaf litter might also be helpful in reducing the primary inculum by enhanced decomposition. Proper pruning allows adequate air circulation in the tree canopy, thereby modifying the microclimate and reducing disease development. Protective sprays of mancozeb (0.3 per cent), carbendazim (0.05 per cent), thiophanate methyl (0.05 per cent), benomyl (0.05 per cent), propineb (0.3 per cent), dodine (0.075 per cent), ziram (0.3 per cent), and fluquinconazole are effective in controlling the disease. However, most of the anti-scab sterol inhibitor fungicides are not effective. The fungicidal spray schedule was recommended in controlling the disease in endemic areas of the state. Disease control has been demonstrated to the farmers field at 15 locations in the Kotkhai areas. Near-total control of the disease has been achieved by the prescribed sprays in Kotkhai, claims Dr Sharma. He has been awarded the PP Singhal Memorial Pesticides Indian Commendation Award for his paper on Marssonina blotch control.

A new project entitled “Biology, epidemology and integrated management of marssonina bltoch causing pre-mature leaf fall in apple” has been sanctioned by the ICAR. The work will be helpful in understanding the disease and its effective management with less number of spraying per season. The project will study the disease at the world level, stated Dr Sharma. It is for the first time that a comprehensive study of this disease has been taken up anywhere in the world. The disease had acquired epidemic proportions in our country, he added.

Do we need harvesting machines?
by Bharat Dogra

THE recent lobbying by powerful interests in the Maharashtra sugar cooperatives for the import of sugarcane harvesting machinery has revived the old controversy on the desirability of mechanising the harvesting work in Indian agriculture. The earlier debate had taken place in the context of wheat harvesting, while the present debate is in the context of sugarcane, but the essential issues remain the same.

In the early Green Revolution years wheat was the most important crop covered by the new technology. Along with chemical fertilisers, mechanisation of various farming operations was also promoted rapidly. While the government continued its support for the spread of tubewells, tractors and threshers, it soon began to have second thoughts about the rapid spread of combine harvesters, and for good reasons.

First, it was rightly pointed out by several agricultural economists that in many Indian villages, harvesting is the only time for some solid earnings by landless farm workers. It is this group which suffers the most poverty and deprivation in most Indian villages. Landless (or near landless) workers toil the hardest to produce our food, yet they are the ones whose own food security is most precarious. The only time they get near full employment opportunities is the harvesting time. What is more, in many villages a substantial part of payment is in the form of the grain harvested by them. Hence they can store foodgrain for the lean months ahead.

Keeping in view the importance of manual harvesting work for farm workers, it was rightly pointed out by many farm economists that this work should not be mechanised. Fortunately, this viewpoint had several supporters within the government. At that time wheat harvesters had spread to only some big farmers in a few villages of the Nainital Terai region (read Shahid Udham Singh Nagar now) and Punjab. The government decided not to promote the use of combine harvesters in a wider area. Since a harvester is an expensive machine and not many Indian farmers can buy it on their own without government loans and subsidies, the spread of combine harvesters remained confined to a relatively small region.

Apart from saving the employment of many farm workers, this had an additional benefit of saving a lot of dry fodder. The technology of combine harvesters is such that the significant amount of dry fodder provided in the case of manual harvesting is completely lost in mechanised harvesting. Although there has been some talk of improving harvesting machines in such a way as at least a part of the fodder can be saved, most harvesters at work in villages or in industrial/university farms still cause an enormous loss of fodder. This is a serious loss for animal husbandry and dairying activities already suffering from a serious shortage of fodder.

Thanks to the checks placed on further growth of combine harvesters in the Green Revolution belt. Punjab and Haryana can still provide a lot of dry fodder to drought hit Rajasthan and Gujarat. This would not have been possible if combine harvesters had spread widely in the wheat-rich Green Revolution areas.

The loss of wheat fodder is not a serious loss in Western countries where the emphasis is on protein-rich cattlefeed and crop residues are not important for feeding cattle. However, for India farm crop residues still remain an important source of feeding various farm animals. Hence any loss of fodder caused by mechanised harvesting should be avoided.

The present context of the debate relates mainly to sugarcane harvesting. Speaking on behalf of the sugar cooperatives of Maharashtra, Mr Sharad Pawar has told two major sugarcane harvester manufacturers from Germany and Australia that mechanisation is acceptable and funds are tied up for buying machines. Some sugar barons have been exerting pressures to start mechanical harvesting of sugarcane right from this year. Price negotiations are already on (a single machine is likely to cost up to Rs 13 million or so) to import the machine in time for the next harvesting season.

It is likely that some modifications will have to be made in these farm machines to suit Indian farm conditions before these are exported to India. The manufacturers are likely to agree to this only if a significant number of machines are ordered or if long-term orders are assured. In both these cases, the impact on the loss of livelihood of farm workers can be substantial. In many sugarcane villages the harvesting time is the main earning opportunity for farm workers living there. In other sugarcane villages, migrant farm workers from some of the most impoverished regions come to seek work at harvesting time.

Sugar barons who have asked the government and banks for liberal loans as well as reduction of duties to facilitate the import of these machines are unlikely to be too concerned about the livelihood of farm workers, but surely the government cannot afford to take a similar view. In addition, the government will also have to consider any adverse impact the new harvesting machines may have on the availability of fodder. The fodder that becomes available during the manual harvesting of sugarcane should not be lost. All these aspects should be fully considered before any decision on the import of surgarcane harvesters is taken.

Farm operations for January

Dairy farming

— Immediate help of nearby veterinarian be sought if animals show lack of appetite, sluggishness or high temperature.

Poultry farming

— Avoid entry of cold wind inside the shed. If the curtain of shed gets wet due to rain, etc. provide dry curtains in the shed, otherwise wet curtain will be harmful. The entry of air through wet curtain will increase coldness inside the shed.

— Damp/caked litter may be removed and can be added again after drying. Part of damp litter may be replaced but the entire old litter may not be taken out. New litter has very little capacity to absorb moisture.

— Poultry feed should have additional 5 per cent energy cereals. Birds require additional energy to overcome the stress of cold weather.

— Put dry grass or husk over the roof of the shed. It will help maintain higher temperature inside the poultry houses.

— Vaccinate the healthy chicks of 6-8 weeks with R2 B vaccine against Ranikhet disease.

— Provide vitamin supplemented water to vaccinated chicks.

— Ensure proper brooder temperature to the young chicks according to their age. In case of electricity failure alternative source of heat should be provided.

— In case of worm infestation in your birds, deworm the flock every month on the fixed date by giving any medicine such as Vermax, Safersol, Verban, piperazine, etc.

— Add coccidiostats in the ration to prevent its occurrence.

Beekeeping

— Honey bee colonies should be least opened during winter. Under compelling situations the colonies should be examined during noon on some calm and sunny day. Extra cracks and crevices/holes in the hives should be plugged with mud. If the colonies are still under shade these should be shifted gradually to sun by moving about 3 feet daily. The surrounding of the colonies should be kept clean of grasses/weeds. Under prolonged cloudy/misty/rain spell, the colonies may fall short of honey stores. If so, the colonies should be given supplementary feed of thick sugar syrup (2 parts sugar: 1 part water). Continue winter packing of the colonies during January also.

Fish farming

— Maintain water level in the ponds to 4.5 to 5 m to provide warm deeper layers of water during late night/early morning.

— Do not apply any organic manure or inorganic fertiliser, if the colour of the pond water is grass-green.

— Apply quick lime @ 50 kg per acre to prevent the incidence of disease during unfavourable winter temperature.

— Reduce feeding to a maintenance level of 500 g of feed per day per 1000 fish.

— Progressive Farming, PAU