FARMER'S NOTEBOOK
Yellow leaf disease drastically reduces yield in sugarcane
M.J.PRABU
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The infestation is more prevalent in over matured crops
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Photo: SBI
YELLOW LEAF disease (YLD) is a recently identified disease in sugarcane, which significantly reduces the crop yield.
The disease is prevalent in Erode, Coimbatore, Namakkal, Karur, Pudukkottai, Villupuram, Vellore and Kancheepuram districts of Tamil Nadu, which are major sugarcane growing areas.
Since the loss caused by the disease is phenomenal in the fields , efforts should be made to reduce the disease severity and sustain sugarcane productivity, according to Dr. R.Viswanathan, Senior Scientist (Plant Pathology), Sugarcane Breeding Institute (SBI), Coimbatore.
Yellowish midrib
Affected sugarcane crops exhibit a characteristic yellowing of leaves. Usually the disease is noticed as yellowish midrib on three to five leaves from the top. Such symptoms are clearly visible when the crop is five to six months of age.
The symptom may be either confined to a few clumps in the field or spread over larger areas depending upon the severity of the disease.
Crop drying
Large patches of crops drying due to this disease in different regions was noticed during the last two seasons in Tamil Nadu as well as in other states, according to Dr.Viswanathan
The drying is more prevalent in over matured crops. Overall, the disease results in loss of vigour to the sugarcane crops and and the crop dies prematurely.
This disease occurs initially as patches on the leaves and its intensity goes up to 100 per cent in the field.
Poor maintenance of the crop combined with drought conditions aggaravate the severity of the disease.
Almost all the cultivated varieties recorded varying intensities of this disease. When severely affected plant crop is used for ratooning, the ratoon establishment will also be poor, explained, Dr. Viswanathan.
Disease spread
"The disease also spreads to new crops through infected cane stalks which are used for planting. In the field, plant to plant spread of the disease occurs through some insects such as sugarcane aphids," he said. When the infestation is mild, the crop records normal growth.
When it becomes severe, cane thickness and stalk height are significantly reduced.
Since the disease spreads through infected seed materials also planting of disease-free material is a must to prevent disease spread in the field.
Farmers are advised to go for disease-free, clean seed cane for planting. Fresh disease-free sugarcane nurseries are to be raised by obtaining healthy nucleus seeds available at research institutes.
The nursery plots should be monitored periodically for the disease at regular intervals , according to Dr. Viswanathan. Alternatively, going for tissue culture seedlings ensures virus free planting materials.
Failing to take seed management practices would result in serious decline in crop growth, he cautioned.
Disease-free seed
Proper supply of disease-free seed would ensure increased productivity and enhanced sugar recovery in the mills, acccording to him..
For further information, readers may contact Dr. R. Viswanathan, Senior Scientist (Plant Pathology), Sugarcane Breeding Institute (SBI), Coimbatore - 641 007, email: rasaviswanathan@yahoo.co.in, mobile: 94425-43875.
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