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Tuesday, September 29, 2015

Paddy Leaf Roller

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Recently, while I was in Azamgarh at my home village I was reported about several things including migration of villagers to cities, deserted villages, and bad conditions of agriculture. One of my relations there told me that besides drought they were suffering from a new problem with paddy crop and the problem was shown by him after we reached to his paddy field. The leaves were rolled and white streaks appeared on them. After picking out a leaf he showed me the eggs of insect arranged linearly inside the rolled leaf. It not attended in time the problem may cause serious downfall in the paddy production. I advised the man to consult immediately to the block office and to take important advice from there so as to check any further spread of the problem. The problem is caused by leaf roller fly which lays eggs  inside the tubular leaf, and the leaf is made tubular by rolling the same with the help of a highly sticky silken thread that is produced by the fly itself. The eggs give births to a number of larvae that eat away the green layers of leaves. Here are the details about the insect directly quoted from the Rice Knowledge Bank.

Leaf roller caterpillars fold a rice leaf around them and attach the leaf margins together with silk strands.
They feed inside the folded leaf creating longitudinal white and transparent streaks on the blade.
Heavy use of fertilizer encourages rapid multiplication of the insect. High humidity and shady areas of the field, as well as the presence of grassy weeds from rice fields and surrounding borders favor the development of the pest.
Expanded rice areas with irrigation systems, multiple rice cropping and insecticide induced resurgences are important factors in the insect’s abundance.
Rice leaf rollers occur in all rice environments and are more abundant during the rainy seasons. They are commonly found in shady areas and areas where rice is heavily fertilized. In tropical rice areas, they are active year-round, whereas in temperate countries they are active from May to October. The adults are nocturnal and during the day, they stay under shade to escape predation. Moths fly short distances when disturbed.
Identification of the insect
Farmers should check the plant for the following symptoms:
(i). longitudinal and transparent whitish streaks on damaged leaves
(ii). tubular folded leaves
(iii). leaf tips sometimes fastened to the basal part of leaf
Heavily infested fields appear scorched with many folded leaves.
Also check for presence of insects, particularly during tillering to flowering. Signs include
·                     disc-shaped ovoid eggs laid singly,
·                     young larvae feeding on the base of the youngest unopened leaves,
·                     folded leaves enclosing the feeding larvae, and
·                     Present fecal matter.
The damage caused by leaf roller may be important when it affects more than half of the flag leaf and the next two youngest leaves in each tiller.
At vegetative phase, crops can generally recover from damage; but when leaf roller  infest at reproductive phase, the damage can be economically important. High feeding damage on the flag leaves can cause yield loss.
Most early season insecticide uses have little or no economic returns. Instead, it can cause ecological disruptions in natural biological control processes, thus enhancing the development of secondary pests, such as plant hoppers.

To prevent leaf roller outbreaks:
·                     Use resistant varieties.
·                     Follow rice with a different crop, or fallow period.
·                     Flood and plow field after harvesting if possible.
·                     Remove grassy weeds from fields and borders.
·                     Reduce density of planting.
·                     Use balanced fertilizer rates.

Spraying pesticides is not advisable during early crop stages. Many farmers in Asia lack the necessary safety equipment and expertise to use pesticides safely and therefore should not use them. See a crop protection specialist for guidance specific to your situation.
Key Words : paddy, leaf roller, farmers,drought

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