Chilli virus disease in Sri Lanka

Technical bulletin of the Tropical Agriculture Research Center
ISSN 03889394
書誌レコードID(総合目録DB) AA00857848
本文フルテキスト
1. A preliminary survey of chilli virus diseases in fields in the major chilli producing areas of Sri Lanka, Jaffna, Puttalam, Vavuniya and Anuradhapura districts, were carried out from 1969 to 1970.
In Jaffna and Puttalam districts which are in the coastal areas, chilli plants are affected more by mosaic type diseases than by leaf curl type disease. In Vavuniya and Anuradhapura districts located inland, the incidence of leaf curl is higher than mosaic type diseases. As mentioned by Peiris (1953), leaf. curl symptoms may be caused not only by leaf curl virus which is transmitted by whitefly but also from feeding injury by mites and thrips. The symptoms are almost indistinguishable in the fields. In the case of plants having infection of mosaic and leaf curl, symptom of leaf curl usually prevails over mosaic symptoms.
2. To identify chilli viruses in the major chilli producing areas, eighty seven samples were collected from Jaffna (38), Vavuniya (8), Anuradhapura (20), Puttalam (1), Badulla (5), and Kandy (15) districts. From seventy eight of these samples, viruses were transmitted by sap inoculation to Capsicum annuum, C. frutescens, Nicotiana tabacum,/i>, N. glutinosa, Vicia fabae, Chenopodium amaranticolor, Phaseolus vulgaris, and Vigna sinensis; from nine samples, viruses were not transmissible by sap inoculation but were transmitted by whitefly and by grafting. All virus isolates were inoculated to test plants such as Capsicum annuum cv. M.I.H., Nicotiana tabacum cv. Bright Yellow, N. glutinosa, Vicia fabae, Phaseolus vulgaris, Vigna sinensis, and Chenopodium armaranticolor. From the results of host range and cross-protection tests, physical properties of viruses, insect transmission, serological tests, and observation of virus particles by electron microscopy, the following viruses were identified: tobacco mosaic virus, cucumber mosaic virus, a strain of potato virus Y, chilli leaf curl virus and an unidentified virus.
3. Potato virus Y is the most common cause of severe chilli losses in Jaffna and is reported for the first time in Sri Lanka. In Jaffna, Matale, and Kandy districts, it was also isolated from tobacco, tomato, and chilli. The virus was transmissible by the green peach aphid, Myzus persicae, and the cotton aphid, Aphis gossypii, and by sap inoculation. The physical properties determined for the virus was: thermal inactivation point 55°-60°C; dilution end point between 1 : 5,000 and 1 : 10,000; and virus longevity between 3 and 4 days at room temperature, or between 9 and 10 days when stored at 5°C. Systemic chlorotic spots, necrotic lesions, vein necrosis, vein net yellowing, stem necrosis, and stunting on Nicotiana tabacum cv. Bright Yellow and Samsun and N. rusticawere obtained. On Petunia hybrida, Physalis floridana, and Capsicum annuum cv. M.I.H., and C. frutescens cv. Honenmidori mosaic reaction was obtained, while Lycopersicum esculentum cv. Fukuju showed slight mosaic symptoms. Diffuse chlorotic spots to mottle appeared on upper leaves of N. glutinosa, Chenopodium amaranticolor, Capsicum frutescenscv. Tabasco developed local lesions on inoculated leaves. In Solanuum tuberosum cv. Arka local reaction was obtained when kept in a dark box for 24 hours after inoculation.
Cross-protection tests between this virus and an authenticated potato virus Y from Japan indicated that both viruses are closely related. Virus particles are of length varying from 500 to 800 nm, with estimated normal length of 700 to 750 nm. Ultrathin sections of infected mesophyll cells showed large areas of cytoplasm containing pinwheels, laminated agregates, and cylindrical inculsions, similar to those induced by several other member of potato virus Y.
4. Chilli leaf curl virus was transmitted by grafting infected chilli to healthy chilli and tomato seedlings, but it could not be transmitted to tobacco. It was also transmitted by whitefly, Bemisia tabaci. The whiteflies transmitted the virus following a 30 min. acquisition feeding time on infected plants, but failed to do so after 10 min. acquisition feeding time. Rate of transmission increased more than for 48 hours of acquisition feeding. Transmission was observed after an inoculation feeding time of 60 min. on test plants, but not after 30 min.. A single whitefly allowed to feed for 3 hours on infected plants was able to transmit the virus within 1 day after initiation of acquisition feeding. The whiteflies transmitted the virus for 12 to 15 days after acquisition feeding. The virus thus persists in its vector, but not for the full span of the whitefly. The virus was not transmitted to progeny of the vector. The following plants were susceptible the chilli leaf curl virus; Petunia hybrida, Lycopersicum esculentumcv. Fukuju and cv. Ponterosa, Physalis floridana, P. peruviana, Ageratum conyzoides,and Datura stramonium. N. tabacum cv. Samsun and cv. Bright Yellow produced slight leaf curvature and outward curling, but no enation symptoms.
There are two kinds of viruses causing leaf curl of tobacco: one which produces enations on leaves and the other which produces no enation. Tobacco leaf curl with enation (TLCV-1) was transmissible to tomato, L. esculentum cv. Ponterosa, and tobacco, N. tabacum cv. Bright Yellow and cv. Samsun, by whitefly and by grafting, but not to chilli, Capsicum annuum cv. M.I.H. Tobacco leaf curl without enation (TLCV-2) was transmissible to tomato, tobacco, and chilli by whitefly and by grafting.
There is observed no enation in leaf curl of tomato in Sri Lanka. This tomato leaf curl without enation (ToLCV) was transmissible to tomato, tobacco, and chilli by whitefly and by grafting. No enation was produced on tobacco.
Chilli leaf curl was not transmissible to tobacco by grafting, but it could be transmitted to tobacco by whitefly under this experimental conditions. No enation was produced on tobacco. It is thus clear that the virus of tobacco leaf curl with enation on tobacco (TLCV-1) is distinct from that of tobacco leaf curl without enation on tobacco (TLCV-2), and the latter (TLCV-2) may be the same virus as tomato leaf curl virus and chilli leaf curl virus.
5. Insecticidal control trials were made in Jaffna (dry zone) and in Peradeniya (wet zone) during Maha 1970/1971 and Yala 1971. Sumithion spray and Ekatin-TD granules applied to soil were highly effective against mosaic diseases in Peradeniya, while Ekatin-TD granules gave better control over PSP-204 granules and Sumithion and Cyanox sprays in Jaffna. The use of these insecticides markedly increased the yield of chilli. Ekatin-TD granules and PSP-204 granules were more effective than other insecticides against leaf curl. It could be that these systemic insecticides rather controlled mites and thrips, thereby reducing feeding injury by these insects which causes symptoms of leaf curl almost indistinguishable from those caused by virus. In fields where Ekatin-TD granules were used, leaf curl symptoms did not appear for 60 days after transplanting in Maha season, but a low percentage of a mosaic disease was observed. The causal virus of this mosaic disease was identified as tobacco mosaic virus.
6. Presence of tobacco mosaic virus in cigarettes and beedi tobacco of Sri Lanka was tested. A common strain of tobacco mosaic virus was detected from 80 to 100% of cigarettes, but only a low percentage from beedi tobacco. No virus was detected from beedi wrappers.
7. Presence of tobacco mosaic virus in chilli and tomato seeds was tested. The virus was found at a low percentage in chilli seeds from Thinnavelly Farm in Jaffna, but not in tomato seeds from the Division of Botany, Central Agricultural Research Institute, Peradenya.
刊行年月日
作成者 Miyoji Sugiura C.M. Bandaranayake G.H. Hemachandra
公開者 Tropical Agriculture Research Center
8
開始ページ 1
終了ページ 66
言語 eng

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