Wednesday, 9 August 2017

Tomato Leaf Curl Virus disease in Pakistan and its management; A Review

Tomato (Lycopersicon esculentum) belongs to Solanaceae family is an important short duration vegetable crop attacked by many pathogenic diseases. TLCVD is most important which damage the crop very badly and affect the fruit quality and quantity badly. This disease is due to a complex of viruses which are transmitted through the whitefly. To manage the disease control of its vector is very important which is done by using different approaches. Management of TLCVD and B. tabaci through plants extracts, nutrients and insecticides are useful. Climatic conditions helps in development of disease as well as in management of disease. The management of this disease is very important due to the importance of this crop.




History and geographical distribution:

Tomato (Lycopersicon esculentum) belongs to Solanaceae family which also contain some other important crops such as potato, tobacco, eggplant and peppers. Tomato was originated from Latin America and spread throughout the world as vegetable crop. Tomatoes are very important due to short duration crop contributing a healthy diet by providing rich amount of minerals, essential amino acids, sugars, fibers etc. (Glick et al., 2009). A number of biotic and abiotic factors affect the quantity and quality of tomato fruit. Among the pathogenic diseases the viral diseases are most important. Tomato leaf curl virus is a serious threat to this crop. Basically it is a complex of viruses. This complex of viruses in Pakistan, India and Australia region is known as TLCV (tomato leaf curl virus) and in Israel and Europe region called as TYLCV (tomato yellow leaf curl virus (Pandey et al., 2009). TYLCV was reported firstly in Israel region in 1920 which appear in epidemic form in 1960 (Glick et al., 2009).

Symptomology and host range of TLCVD:



TLCVD affected plant show a number of symptoms which are reduction in leaf area as well as leaf size, stunted growth, puckering of leaf, upward curling, vein clearing, abnormal shoot proliferation, deformation of leaflets and reduction in yield quantity as well as quality. Tomato is the primary host of this disease. Some other plants are also acts as its host are bean (Phaseolus vulgaris), lisianthus (Eustoma grandiflourm) and petunia (Petunia hybrid) are also host plants of TYLCV. Some weeds including Cleome viscose (Caparidaceae) as well as Carton lobatus (Euphorbiaceae) are also susceptible against TYLCV but no disease symptoms are produce (Kurata et al., 2016).




Pathogen vector relationship:

Bemisia tabaci (whitefly) is a most important insect pest which harm the tomato plants by direct feeding and by transmitting the viral pathogen from diseased plant to healthy plant. Social and economics studied show that the farmer can gain up to 10 times more profit by growing resistant tomato against whitefly (Colvin et al., 2012).

Management of TLCVD and B. tabaci:

To manage this disease the control of insect pest vector is very important which is done by different methods. A few of them are as fallow

  • Management through plant extracts:

Chemical control method is the major method for the management of insect pest but it become less effective due to resistance develop in insect pest against the insecticides (Siebert et al., 2012). B. tabaci adults, nymphs and eggs are found resistant against the chemicals so plant extracts are used. As the chemical control of insect pest is costly so the plant extracts are more effective than the chemicals. Foliar spray of Neem (azadairachtin) and neem plus can kill the eggs, nymphs and adults of B. tabaci. Ethanolic and aqueous extracts of Annona squamosal, Carlowrightia myriantha, Trichillia arborea, Azadirachta indica and Acalypha gaumeri are effective against B. tabaci population. Neem oil, garlic and eucalyptus extract give significant result against this disease (Khan et al., 2013).

  • Management through insecticides:

The chemical control method is easy and most commonly used approach against the insect pest. A number of insecticides are used. Among them imidacloprid, acetamiprid, nitenpyram, thiamethoxam and diafenthiuron give significant result against aphids, whiteflies and other insect pests (Bacci et al., 2007). The comparative efficacy of these insecticides show significant result against this disease. These chemicals are very effective against the B. tabaci and TLCVD (Zeshan et al., 2015).

  • Management through nutrients and systemic acquired resistance:

Plant health play an important role the management of a disease. Nutrients play an important role in plant health which enable the plants to fights against the chewing type insects. Therefore the nutrients (N, P, K, Zn, and B) are very important in crop health and these nutrients were evaluated. The application of micro and macro elements can affect the relationship between the insect pest and plants. Studied shows that Zinc improve the defense system of plants. Plants with higher amount of N, P, K, and B give significant result against the disease. Some of these nutrients act as cofactor in enzyme activation (Maathuis et al., 2009).

Conclusion:

Tomato is cultivated in Pakistan and India also in other countries of Asia as well as throughout the world due to its high nutritional value and short duration crop. A number of biotic and abiotic factors affect the quantity and quality of tomato crop. Among the viral diseases TLCVD is very important which is a serious threat to tomato crop. To manage this disease it is very important to control its vector first. For this purpose a number of approaches are used which includes the management through plant extracts, through the nutrients and through the insecticides. Cultural practices, removal of host plant, vector control and crop rotation are also useful approaches against the disease.

References:

Bacci, L., A.L. Crespo, T.L. Galvan, E.J. Pereira, M.C. Picanço, G.A. Silva and M. Chediak. 2007. Toxicity of insecticides to the sweetpotato whitefly (Hemiptera: Aleyrodidae) and its natural enemies. Pest manage. Sci. 63(7): 699-706.
Colvin, J., N. Nagaraju, C. Moreno-Leguizamon, R. Govindappa, T.M. Reddy, S. Padmaja, N. Joshi, P.M. Hanson, S.E. Seal and V. Muniyappa. 2012. Socio-economic and scientific impact created by whitefly-transmitted, plant-virus disease resistant tomato varieties in southern India. J. Integrat. Agric. 11(2): 337-345.
Glick, E., Y. Levy and Y. Gafni. 2009. The Viral Etiology of Tomato Yellow Leaf Curl Disease. Plant Protect. Sci., 45(3): 81-97.
Khan, M.H., N. Ahmad, S. Rashdi, I. Rauf, M. Ismail and M. Tofique. 2013. Management of sucking complex in bt cotton through the application of different plant products. Pak. J. Life Sci, 1(01): 42-48.
Kurata, A., A. Fujiwara, N. Haruyama and T. Tsuchida. 2016. Multiplex PCR method for rapid identification of genetic group and symbiont infection status in Bemisia tabaci (Hemiptera: Aleyrodidae). J. Appl. Entomol. Zoo. 51(1): 167-172.
Maathuis, F.J. 2009. Physiological functions of mineral macronutrients. Current opinion in plant biology, 12(3): 250-258.
Pandey, P., N.R. Choudhury and S.K. Mukherjee. 2009. A geminiviral amplicon (VA) derived from tomato leaf curl virus (ToLCV) can replicate in a wide variety of plant species and also acts as a VIGS vector. J. Virol. 6(1): 152.
Siebert, M. W., J.D. Thomas, S.P. Nolting, B.R. Leonard, J. Gore, A. Catchot, G.M. Lorenz, S.D. Stewart, D.R. Cook, L.C. Walton, R.B. Lassiter, R.A. Haygood and J.D. Siebert. 2012. Field Evaluations of sulfoxaflor: a novel insecticide against tarnished plant bug (Hemiptera: Miridae) in cotton. J. Cotton Sci. 16:129–143.

Zeshan, M.A., M.A. Khan, S. Ali and M. Arshad. 2015. Correlation of conducive environmental conditions for the development of whitefly, Bemisia tabaci population in different tomato genotypes. J. Zool. 47(6): 1511-1515.







About Author:
Muhammad Jahanzaib
Department of Plant Pathology
University of Agriculture, Faisalabad-38040, Pakistan

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