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| AGRICULTURE TRIBUNE | Monday, August 26, 2002, Chandigarh, India |
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Peach not in the pink of health Undo root-knot Tomato-killer tospo virus Farm operations for Sept |
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KNOW THE DISEASE Apple has become a major cash crop in Himachal Pradesh and is being cultivated over 83 per cent area under fruit crops in the state. Due to intensive cultivation over a vast area, it is subjected to a number of diseases that lower the fruit yield and quality drastically. Root and collar rot During a recent survey carried out in Shimla district, it was observed that orchards were free from the scourge of apple scab and Marssonina blotch diseases which was a matter of serious concern to the fruit growers in the past few years. However, the orchardists of Kotkhai, Thanedhar and Sarahan apple belts are still struggling to control white root rot and collar rot diseases. These diseases result in the death of apple trees by destroying the roots and stem portions near the soil line, respectively. Most of the orchardists fail to diagnose these maladies early and come to know about the attack when most of the damage has already occurred. Orchardists are advised to be on the lookout constantly for these diseases and follow proper diagnostic approach since most of the underground/ root-zone disturbances cause above-ground symptoms like sparse growth, restriction of leaf and fruit size, and shedding of foliage, resulting in a sick appearance of the trees. Soil drenching with fungicides is effective subject to proper diagnosis made well in time. Nevertheless, white root rot in apple can be effectively controlled by soil drenching with 0.1 per cent carbendazim. This fungicide should be put in 8-10 inch deep holes made 1 ft apart throughout the tree basins when there is sufficient moisture in soil during July and August. For the control of collar rot disease, the infected collar region of the trees should be scarified with the blunt side of a knife and pasted with copper oxychloride or mancozeb or metalaxyl. Apart from this, the soil surrounding the stems should be drenched with the solution of above fungicides up to 1 1/2 ft radius. Replant problem Specific apple replant disease (SARD) is a well-known problem world over. However, in Himachal Pradesh, a few orchardists at Kotkhai and Nandpur, Jubbal, have successfully planted apple trees in 35-40 year old orchards. There is no specific treatment for this. Nevertheless, their experience has shown that newly planted trees should be in a proper layout and treated for the known disease and pest problems. In one study in Kotkhai a few years ago, no sickness was recorded in the orchard soils. The test soil samples collected from 1-60-year-old orchards supported good growth of apple seedlings in pot culture trials. Also, the annual extension growth shown by standard Royal Delicious trees planted in a 35-year-old orchard was satisfactory without any signs of weakness. One orchardist has replaced successfully his 40-year-orchard with spur-type apple cultivars, mainly Red Chief, in a phased manner. The replanted trees had borne full crop after nine years. Virus Apple plants in Kotkhai, Jubbal, and Thanedhar fruit belt were found affected by virus diseases. The incidence was as high as 40 per cent in a few orchards. The disease symptoms include mosaic, mottling, curling and distortion of leaf lamina. Typical necrotic lesions of different types, sometimes resulting in blight symptoms, have also been recorded. Such spots did not reveal the association of any fungal or bacterial pathogens and are appearing year after year despite regular sprays of broad-spectrum fungicides. Whether they are the result of any physiological imbalance or otherwise is yet to be ascertained. However, control of viral diseases of apple can be achieved by using virus-free planting material. A few fruit grower associations and progressive orchardists have already started importing virus-free nursery rootstocks. The imported material is being grown under protected conditions in the Kotgarh area and post-entry quarantine inspection of the material was carried out. The orchardists were advised to follow recommended plant protection measures to save the valuable material against the attack of resident pathogens like powdery mildew and root rot. The Department of Mycology and Plant Pathology, Dr Y. S. Parmar University of Horticulture and Forestry, Solan, has already supplied virus-free planting material for establishing orchards of improved colour strains of apple at the main campus in Nauni, besides Kotkhai, Seobagh (Kullu) and Sharbo (Kinnaur), research stations of this university. Apart from viral attacks, apple fruits nearing maturity are liable to be attacked by a number of fungal pathogens, viz., scab, Marssonina blotch, sooty blotch and fly speck diseases. These diseases can reduce the quality of the produce tremendously and inflict huge losses on growers. The orchardists are advised to spray mancozeb (0.3%) or carbendazim (0.05%) or ziram (0.3%) at 15-20 days interval before harvest. |
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Peach not in the pink of health Peach is an important remunerative fruit crop for growers of Himachal Pradesh, ranking next only to apple and plum. Growers of the Rajgarh valley in Sirmour district have attained a high level in the production of quality peaches, as a result of which the area has come to be known as the peach bowl of Asia. However, for the past few years peach growers have been facing a problem of a yellow disease that was previously thought to be the peach-X disease known in North America. In Himachal Pradesh, the disease was first noticed during the mid-1980s on a few trees in orchards in and around Siana village in Rajgarh area. The disease has assumed alarming proportions since. Experts of Y. S. Parmar University, Solan, have found affected orchards in Junio, Matnali, Kotli, Karyut, Siana, Bhat ka Siana and Bhuria (Dahan road). The number of diseased trees ranged from a few to as high as 400 per orchard. Phytoplasmas, earlier called mycoplasma-like organisms (MLOs), belong to a relatively new class of prokaryotic disease agents—mollicutes which are similar to bacteria but lack cell walls and are limited to growing in the phloem of host plants. It is generally believed that phytoplasmas cause symptoms of yellowing, phyllody and witches’ brooms due to hormonal imbalance in the plant. These organisms are spread by phloem-feeding vector insects, mostly leaf hoppers, plant hoppers and psyllids. In vegetatively propagated plants like temperate fruits, infected bud wood and plant material also spread the pathogen. Symptoms Peach trees infected with phytoplasma causing yellow leaf disease exhibited typical symptoms of yellowing and upward marginal rolling of leaves. Partial infection confined to a branch or few branches is common. Occasional red spotting and tattering accompanied by swelling of veins is also evident on some leaves. The diseased tree or branch bear small and shrivelled fruit that drops prematurely. Diseased trees shed their leaves early. Plants infected at a younger stage usually die, however, older trees sometimes continue to survive with poor productivity. Since the symptoms are more pronounced during these months in the form of typical yellowing and reddening of leaves visible from a distance, orchardists can easily identify the ailing trees. This phytoplasma has been identified to be a member of the elm yellow group of phytoplasmas. It is hitherto unrecorded in peach, hence found to be the first of its kind infecting peach plantations in Himachal. The disease associated with it is named Indian peach yellow leaf roll. Treatment Like other viral diseases, complete control of phytoplasma diseases is difficult. However, for checking the spread and to manage the infection the following recommendations are made by Y. S. Parmar University: —For new orchards, procure only certified disease-free plants. —Young infected plants should be uprooted and replaced with healthy ones. —In partially infected trees, where the infection is limited to a few branches, remove the infected part to save the rest of the tree. —Infected trees should be treated with antibiotic oxytetracycline hydrochloride @ 1g/tree in the form of trunk infusion or injection. This treatment should be carried out in August and September, i.e., before 1eaffall. For learning the technique of injecting antibiotic, growers are advised to contact the nearest horticulture officer or the Department of Mycology and Plant Pathology, Parmar University. |
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Undo root-knot Root-knot is a serious disease of vegetables, pulses, fruits and ornamentals. Caused by a nematode (Meloidogyne spp.), it is present throughout the country. The losses from it are more in sandy soil. Apart from quantitative losses, the nematode also affects the quality. Due to this disease, total failure of certain crops like hybrid tomato, okra and cucurbits is possible. Here we take a look at the practices that aggravate or reduce the disease: Wrong practices:
Growing one nematode-susceptible crop after another in an infested field, ploughing in roots of infected plants and ratooning of infected crops like brinjal increase the disease in succeeding crops. Right practices: Crops in the fields with sufficient farm manure have less damage. It is observed that a nursery grown under a neem tree is healthier. Neem leaves and seeds have been found effective against root-knot nematode. Good crops of tomato, brinjal and cucurbits have been obtained after guar crop. Garlic and guar are non-host crops for this nematode, so these could be cultivated as rotational crops in infested fields. Misconceptions:
The following are some of the misconceptions about this disease: root galls on tomato, chillies, etc., are due to ‘marodiya’ (leafcurl); root-knots (galls) are formed due to poor quality seed; and bacterial nodules on leguminous plants are mistaken for nemotade galls. It is clarified that root-knot disease is soil borne and affects susceptible plants. It is different from bacterial nodules on roots of leguminous plants or viral diseases causing leafcurl. Management: Besides the general recommendations like summer ploughing, use of chemicals in nursery beds, resistant varieties and hybrids in tomato, etc., the following points may be observed: Use manure; after the crop, infected roots and stubble should be removed and burnt; leave field fallow for some period; do not allow weeds in fallow field and in resistant/non-host crops. |
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Tomato-killer tospo virus Tospo virus in tomato is also called tomato spotted wilt virus (TSWV). The disease causes severe losses (10-100%), depending on the stage of infection. This virsus also causes disease in important crops like chilli, watermelon and capsicum. The symptoms expressed on plants vary from part to part, depending on the stage of infection. Young leaves show small, dark-brown spots and eventually die. Dark brown streaks also appear on stems and leaf petioles. Growing tips are affected with systemic necrosis leading to tip die-back and stunted growth. Flower buds dry and drop, leading to severe yield loss. Unripe fruit will have mottled, light green rings with raised centers. On ripening, orange and red discolouration patterns make it unmarketable. The virus is transmitted by a vector called thrips. The tiny thrips are slender, straw yellow to brown and have long fringed wings. Thrips are carried by wind and clothing. Mass spraying is most effective in controlling thrips. Commonly, tomato seedlings are the source of inoculum. Spray the nursery once in 7-8 days with monocrotophos 1.5 ml/lt and neem oil 2-5 ml/lt. Alternate sprays with acephate will help keep away the insects. The occurrence of virus infection is related to the season — long availability of thrips, virus, presence of reservoir crops and perennial weed hosts. Exclusion and sanitation are the important factors in controlling the disease. The use of resistant/tolerant hybrids is advised. In the main field the following schedule of sprays is recommended: — Monocrotophos (1.5 ml/lt), Dimethoate (1 ml/lt) — Imidacloprid (0.2-0.5 ml/it), Acephate (1.5 ml/lt) — Garlic (5 g/lt) + Asafoetida (1 g/lt) — grind well, filter, use for spraying, — Marshal (1-2 ml/lt), Prefenofos 50% EC (2-3 ml/lt) (Note: Mix neem oil (2-5 ml/lt) and sticking/spreading agent (0.5 ml/lt) in every spray. Repeat the sprays once in 10 days. Repeat garlic and asafoetida sprays 3-4 times.) |
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Farm operations for Sept PADDY — Provide irrigation regularly to the crop and stop irrigating two weeks before harvesting. — Rogue out the weeds and off-type plants. — Control leaf folder by spraying 250 ml of Folithion/ Sumithion/ Accothion 50 EC or 150 ml of Lebaycid 1000 EC or one litre of Coroban/Durmet 20 EC or 560 ml Nuvacron/Monocil 36 SL in 100 litres of water per acre. — White backed plant hoppers at times become serious in rice. The crop dries up in patches. The plant hoppers can be controlled by spraying 40 ml of Confidor 200 SL or 250 ml of Lebaycid or 800 ml of Ekalux 25 EC or 1000 ml Ekalux 20 AF or one litre of Coroban/ Dursban 20 EC or 560 ml of Thiodan 35 EC/ Nuvacron 36 SL in 100 litres of water per acre. — Paddy stem borers feed on growing points and cause dead hearts and white erect ears. Cheek attack of borers in basmati rice by spraying 560 ml of Nuvacron/ Monocil 36 SL (monocrotophos) or one litre of Coroban/ Dursban/ Lethal/ Chlorg-uard/ Durmat/ Classic 20 EC (Chlorpyriphos) in 100 litres of water. Give 5 sprays at 30, 40, 50, 60 and 70 days after transplanting by using the above insecticides alternately. — To avoid sheath blight, keep the bunds clean. On noticing the disease, spray with Bavistin @ 200 g/200 litres of water per acre. MAIZE — Maintain adequate water supply, particularly at tasseling and silking stages. Stress at these stages causes considerable loss in yield. — The attack of maize borer can be checked by spraying 40 ml of Sumicidin 20 EC/Ripeord 10 EC or 80 ml of Decis 2.8 EC in 50 litres of water/acre. COTTON — Do not allow cotton crop to suffer for want of water during flowering and fruit stages, otherwise af lot of shedding of flowers and boils will take place, resulting in poor yield. — Check attack of bollworm by spraying 800 g Acephate 75 SP or 800 ml quinalphos 25 EC or 850 ml fenitrothion 50 EC per acre. In case of a serious attack, spray 2 litres of chlorpynophos 20 EC immediately. Repeat the spray if it rains within 24 hours of spraying. In case mite/aphid/jassid and whitefly appear alongwith bollworm, use monocrotophos and triazophos or ethion, respectively. |
