|
www.caisnet.org
|
Onion Pests & Diseases |
|
Integrated Pest Management BibliographyEdelson, J.V. et al. Onion cultivar yield response to onion thrips infestations. (Texas Agricultural Experiment Station. Progress Report; no. PR4815) 3 p. Ten commonly grown dry bulb onion (Allium cepa L.) cultivars were compared to differentiate the impact of onion thrips (Thrips tabaci Lindeman) on yield. Onions were either treated with aan insecticide to control thrips or lef untreated. Thrips populations were monitored during the growing season and were maintained at low levels (5 per plant) in the treated plots. Onion bulbs were harvested at maturity, weighed, and sized to commercial grades (i.e. jumbo, large, medium). significantly larger populations of thrips were maintained on untreated onions compared with treated onions. Significant differences in percentage of bulbs that graded jumbo size were noted for five cultivars. No differences in percentage jumbo bulbs were noted between treated versus nontreated plots for 'Texas Grano 502', 'Early Supreme', 'Granex 33', 'Yellow Granex', or'Red Garnex'. Interaction of treatments and cultivars was evaluated using analysis of variance. A significant interaction was indicated between treatment (insecticide treated versus non-treated) and cultivar. Thus, indications are that differences exist among onion cultivars in ability to tolerate thrips damage as evidenced by reduction in percentage of jumbo bulbs. (02413) Gupta, R.N.; Pandey U.B. 1986. Diseases of onion and their control. REVIEW OF TROPICAL PLANT PATHOLOGY v. 3 p. 321-360. (01936) Paulraj, L.; O'Garra, L. 1992. Aspects of the epidemiology of a leaf blight of onion in Barbados. Proceedings of the tenth annual conference, Grand Barbados Beach Resort, Barbados West Indies, Nov 11-13, 1992. [St Michael](Barbados): BSTA. Proceedings of Barbados Society of Technologists in Agriculture; (no. 10) p. 89-96. A leaf blight of onions referred to locally as onion "blast" was recently shown to be caused by a new pathovar of Xanthomonas campestris (Paulraj and O'Garro, 1992). The disease is widespread in occurrence and it is considered to be the main constraint to the expansion of the local onion industry. Attempts to control the disease by chemical and cultural methods have been generally futile because basis aspects of the epidemiology are unknown. This study reports on the population dynamics of onion strains of Xanthomonas campestris and the occurrence of onion blight in the field. The effectiveness of chemicals commonly used to control the disease is also evaluated. (03365) |
|
Links:
| ||||||
