RED ROT OF SUGARCANE
The crop is subjected to many diseases caused by fungi, bacteria, nematodes and viruses
By M. Mithal Jiskani
Feb 12 - 18, 2001
Sugarcane is not only cash crop for the growers, but it is main source of white crystal sugar and also provide grower with a very good substitute of sugar in the form of 'gur' and 'khandsari' (brown sugar). While sugarcane tops serve as fodder for cattle, baggase and leaf trash as fuel, stubbles and roots as organic manure and crop residues as mulch and compost. Since last two decades, sugarcane leaves are also used as substrate for the artificial cultivation of edible mushrooms.
This crop is subjected to many diseases caused by fungi, bacteria, nematodes and viruses. According to Ahmad (1988) red rot is one of the oldest and widely distributed, recognized as major disease of sugarcane in Punjab and Sindh. But Hafiz (1986) described this disease as third most important disease by reporting that "red rot of sugarcane was first recorded from Java in 1883 and in the sub-continent of Indo-Pakistan by Barber and later on by Butler in 1906". Kamal and Moghal (1968) reported this disease in a local variety of sugarcane during 1921-22 at Sukkur, Sindh.
However, the causes of the disease, its symptoms, transmission, perpetuation and control measures, based on the description by Hafiz (1986) and Ahmad (1988), are being summarized here under, for guide line to the growers, extension workers and students of agriculture.
Cause of the disease:
Red rot of sugarcane is caused by a fungus: Colletotrichum falcatum, has its perfect stage as Physalossora tucumanensis Speg. While some scientists have named it as Glomerella tucumanesis Von Arx and Muller (Hafiz, 1986).
All parts of the plant, above the ground are being infected by the disease, but first appears as red bright lesions with ash grey centers on the mid rib of leaves and shows itself in the form of drooping and changing of color of upper leaves, when the plants approach maturity (from September - October to onwards). Withering of the leaves proceeds downwards with the progress of disease. Usually third or the fourth leaf from the top is affected and later on the whole crown withers and droops. In severe cases, the pith gradually dries up and the cone becomes shriveled and looses its weight. At this stage fruiting bodies of the fungus develop on rind, usually just below or above nodes. When the infected canes are split open they five out an alcoholic or acidic starchy odour due to fermentation, and shows reddish color areas. The size of lesions on leaves and reddish areas on cane, varies from variety to variety, and if only few are present, such areas may be relatively large but if numerous these generally remain small.
Rain and irrigation water play major role in carrying out fungus or infectious material from one plant to another (or one field to the other). Wind and insects may also help in spreading the disease causing fungus.
The disease perpetuates from year to year through soil and planting the diseased canes or through decaying leaves, and also through the diseased cane lying in the field. Whereas, ratoon crop may also help greatly in multiplication and penetration of the fungus.
1. Cultivation of disease resistant varieties is alone safe control measure.
2. Crop rotation for two years should be adopted.
3. The seed setts should be disease free or must be treated with suitable fungicides.
4. Diseased plant parts should be collected and burnt, in the standing crop as well as after harvesting.
5. Ratoon cropping should be discouraged, if first crop is found to be suffered due to disease.
Ahmad, I. 1988. Fungal Diseases of Sugarcane. In "Plant Disease Diagnosis Manual, Vol.2". CDRI, NARC, PARC. Islamabad. p.24-30 Hafiz, A. 1986. Plant Diseases. PARC, Islamabad. p.103-116. Kamal, M. and S.M.Moghal.1968. Studies on plant disease of south West Pakistan. ARI, Tandojam.p.3.
The author is Assistant Professor (Plant Pathology), Sindh Agriculture University, Tandojam.