Sugarcane in Goa is infested by following pests and diseases. Their nature of damage and control measures are suggested below:
1.Sugarcane Wooly aphid
Sugarcane woolly aphid is a foliage sucking pest. Wooly aphid earlier was known to be a minor pest in India but has now assumed the status of an economic pest after its severe outbreak in Maharashtra during July 2002. It feeds on sugarcane by inserting their stylets through the stomata of the plant leaves. Both nymphs and adults suck the cell sap from the lower surface of leaves. They suck the sap from the phloem. They excrete a large amount of honey dew which falls on the leaves giving them a sticky coating on which black sooty mould (Capnodium sp.) develops making the leaves look all black. Due to the thick coating of sooty mould process of photosynthesis is significantly hampered in severely infested plants, thereby causing considerable reduction in cane yield (25%) and sucrose content (26.71 %), whereas, during the early growth period plants may die.
1.Use of Wooly aphid tolerant varieties suitable for Goa region such as SNK- 49 and SNK-61.
2. Soil application of Phorate lOG @ 10 kg or Carbofuron 3G @ 30 kg /ha in the infested crop not more than six months old. The granule should be applied with due precautions, along with the low side at the base of the plant followed by light irrigation, if required.
3. Foliar application of Dimethoate 30 EC @ 0.05%, Metasystox 25 EC @
2.Early shoot borer
This insect pest can cause up to 30 percent losses in sugarcane crop. Under Goa conditions, this pest is noticed from March to May. Hot climatic conditions and low humidity are the predisposing factors for the spread of this pest. The female lays eggs in rows in straight lines on the under surface of leaves. The larvae after hatching bore a hole into the growing cane near to the soil surface and feed on tender portion. This results in the death of the central shoot by gradual drying.
Control
1.Destroy all infested shoots.
2. Spray the crop with 35 percent Endosulfan by mixing 14 ml in 10 litres of water 3-4 weeks after germination or spray 50 percent BEG @ 3 kg in 500-litre water twice at an interval of 10 days,
3.Apply in furrows, 6% Gamma BHC (Lindane) @ 16 kg/ha and irrigate. This will also control termites.
4. Avoid late planting of Cane.
5. Do adequate hoeing.
6. Release of biological control agents such as Trichogramma eggs @ 5 lakh/ha or spray with 300 larvae infested with granulosis virus in 250 litres water.
3.Stem borer
The stalk borer in advanced stage infests the sugarcane crop as stem borer. This pest is found during tillering stage and beyond and it makes holes in the cane and feeds on inner contents. These holes are concealed under the dry leaves. The incidence of this pest is favoured by hot weather from February to May.
Control
Adequate control of early shoot borer will ensure crop free of this pest.
4.Scale insect
This pest infests the cane when the tillers start maturing. The nymphs and adults stick on the outer surface of cane and suck the sap, thus devitalizing the plant. The crop remains stunted and dries up. The spread of this pest is through infested setts, air and ants. This pest is more pronounced in ratoon crop. It causes 30-35 percent weight loss and 2 to 3 cent reduction in sugar recovery in the heavily infested crop. Use of infested setts for planting, neglected ratoon, poor soil, water scarcity and drought in summer are some of the predisposing factors.
Control
1.Do not use infested setts for planting.
2. Infested cane should be harvested early and the trash burning. No ratoon is advisable from such crop.
3. Plough the field immediately, collect stubbles and bum them.
4. Provide adequate irrigation.
5. Treat the setts with 30% Dimethoate (Rogor)@265mlor85%Phosphomidon @ 80 ml or 50% Malathion @ 300 ml in 100 litres of water by dipping the setts for 3-4 minutes before planting.
6. Use granular Phorate @ 10 kg/ha when tillering is over.
5.Termites
This insect pest damages the crop at two stages. Once when the setts are planted, when the worker class of termites feed on the tender eye bud resulting in poor germination. They also feed on cut ends of setts and cause germination losses. Later on, when the cane is fully grown, they feed around basal portion as well as cane portion near the ground. Their feeding results in drying of the cane.
Control
1.Locate the termetoria to locate the queen and destroy it.
2. Apply 20% Gama BHC 5 litres III 1,000 litres water in furrows.
In addition to above, the sugarcane is also infested by sap-sucking insect pests such as white-flies and mealy bugs. These can be controlled by spraying any systemic insecticide.
6. Rats
A rat causes damage not only to sugarcane but many other crops. Burrowing of rats into water channel causes loss of water. The rats due to their gnawing habit cause 10% more damage to cane than by eating it. The site of damage is near the joints where the cane is hard. Their damage causes cane to dry and lose weight. Lodging of Cane is many times attributed to burrowing of rats near the base.
Control
Identify the live burrows on bunds and in the fields. Baiting is necessary if Zinc Phosphide is used. More recently, ready to use rodenticide, Bromdiolone 0.005% (Moosh Moosh) or rattol is found to be an effective rat killer. Place 1-2 cakes in each live burrow along bunds, 2-4 weeks after planting. Cakes are also distributed in the field after earthing up at 10-15 m interval. About 30-50 cakes are required for one acre. The rodent control work should be done on a collective basis rather than individually.
7.Wild boars
This is also a menace to sugarcane growers. This can be kept away by having battery operated fencing.
Diseases
Two major diseases infest sugarcane crop in Goa.
1. Grassy shoot
This is a mycoplasma disease which is on a rise in Goa. A large number of lean and lanky pale sprouts appear in the clumps like “Bunchy grass”. The normal stalk (cane) is not formed and the incidence of this disease is more in ratoon crop. This disease is transmitted through setts.
Control
1. Select healthy setts for planting. Setts from the diseased field should be avoided.
2. Uproot and destroy infested clumps by burning as soon as the disease is noticed.
3. Treat the setts in hot water at 50° C for 2 hours.
4. Dip the setts in a solution containing 50 g Bavistin in 100 litres of water 20-30 minutes before planting.
2.Whip Smut
This is a mycoplasma disease which is on a rise in Goa. A large number of lean and lanky pale sprouts appear in the clumps like “Bunchy grass”. The normal stalk (cane) is not formed and the incidence of this disease is more in ratoon crop. This disease is transmitted through setts.
Control
1. Select healthy setts for planting. Setts from the diseased field should be avoided.
2. Uproot and destroy infested clumps by burning as soon as the disease is noticed.
3. Treat the setts in hot water at 50° C for 2 hours.
4. Dip the setts in a solution containing 50 g Bavistin in 100 litres of water 20-30 minutes before planting.
3.Grassy shoot
This is a fungal disease infesting sugarcane crop. The growing point projects a long black whip-like structure covered with black spores. Affected plants have a slender cane and quality is destroyed. The whip is covered with a silvery membrane which if ruptured, give out the black powdery mass of spores which is spread by wind, water or soil.
Control
1.Locate infested clumps and destroy them.
2. Select healthy setts for planting.
3. Follow sett treatment as suggested for grassy shoot disease.
Harvesting
Sugarcane is ready for harvest in about 11- n12 months after planting depending on the variety and the season. The mature cane is yellowish with prominent eye buds, giving a metallic sound if tapped with fingers. Similarly, it breaks at nodes if bent. But, the better indicator for determining the maturity is the Brix reading taken with hand refractometer. If the reading shows 19 and above, the cane is mature and ready for harvest. The stand of subsequent ratoon crop depends on the correct manner of harvesting.
The cane should be cut as close to the ground level as possible with the help of a sharp knife. Care should be taken to give a horizontal smooth cut without damaging the eye bud below the soil. If the cane is harvested above the ground, the yield is reduced, sugar is lost in the lower portion (as the lower portion contains more sugars) and there is lodging as well as poor tillering in the ratoon since the buds sprout from above the ground and have no support. On the other hand, if the cane is cut below the ground, the lower eye bud is damaged and this badly affects germination. Use of improved ‘Vikas’ knife developed by Vasantdada Sugar Institute cuts the cane at the right place with ease and gives a smooth cut thus avoiding the trouble of stubble shaving operation for ratoon crop.
Source-
- Central Coastal Agricultural Research Institute, Ela, Old Goa, Goa
