Evolution of aerial infection of leaf scald in sugarcane
| MSI99P2298 | |
| Saumtally, S. Médan, H. Autrey, L. J. C. | |
| Evolution of aerial infection of leaf scald in sugarcane | |
| BSES - Program and Abstracts, 4th ISSCT Pathology Workshop, Brisbane, Australia, 4th-9th April 1994 | |
| Book chapter | |
| 1994 | |
| p. 32 | |
| Brisbane, BSES | |
| Abstract only | |
| En | |
| In an epidemic of leaf scald that occurred in Mauritius in 1989, abundant foliar stripes were observed in sugarcane and maize. The striping was particularly severe in a few commercial sugarcane varieties (M695/69, M1557/70, M292/70) and in some unreleased clones (M1205/70, M298/71, M1236/71, M791/75), indicating a new mode of transmission other that by cuttings and the possible contamination of plants issuing from disease-free planting material. An experient was therefore set up to follow the progress of foliar infection using disease-free plantlets produced in vitro and one-eye cuttings of variety M695/69 in the east of the island, an area known to be favourable to aerial dissemination. The disease was monitored at weekly intervals and infection was observed 5 months after planting. Yellow stripes about 3 mm wide and later becoming necrotic were found to start at the tip of the leaf, and were present on leaves 5 to 14, with a higher frequency of stripes on leaf 8 and leaf 9 (the youngest unrolled leaf being taken as leaf 1). Some stripes progressed faster that others and 5 months after the first infection was observed, the length of the stripes varied from a few centimetres to 78 cm. It was observed that the old leaves bearing symptoms (usually the 14th) dried up before the stripe entered the leaf sheath. In the same trial, half of the plants were sprayed weekly with copper oxychloride at 2 g/L as soon as they were planted or emerged, in an attempt to control aerial transmission. This dosage was reduced to 1g/L after six months due to phytotoxic effects. Foliar tr e a tment was effective in preventing infection initially. However, stripes were observed in the treated plots when the dosage was changed, but they were still appreciably less than in untreated plots. The percentage of infected stools was reduced from 67 to 11 per cent in in vitro plantlets and from 41 to 17 per cent in plants issuing fron one-eye cuttings. The experiment shows that aerial infection of leaf scld is similar to that of gumming disease. Although no systemic infection has been observed, occurrence of this phase of the disease at a later stage is not excluded. The trial will be followed in first ratoon. | |
| SUGARCANE LEAF SCALD AIRBORNE INFECTION DISEASES DISEASE CONTROL | |
| MAURITIUS | |
| Sugarcane: Diseases and disease management | |
| 1996-08-08 | |
| En | |
| PATH | |
| PATH |