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100 Glorious years of Sugarcane Breeding Institute

Tuesday, 26 February 2013

Pest advisory for Sivaganga region /Pheromone traps-Tamil-CaneInfo



Advisory issued by Dr J Srikanth, Senior Scientist (Agricultural Entomology) , Sugarcane Breeding Institute, after his survey in the region during September, 2012. 

The management practices to be followed for individual pests are given below:

I. Mite

            Since moderate temperature and moderate to high relative humidity generally favor the multiplication of yellow mite, it is essential to monitor the crop under such conditions. Mite infestation in shaded border area of the field visited as well as its reported occurrence in unshaded fields indicated the possibility of its initiation in shaded areas and subsequent spread to interior areas.

Management practices

1.      The conventionally used insecticides/acaricides such as dimethoate, quinalphos or dicofol at 0.05% would still be useful to bring down the high populations of the mite, especially due to no adverse reports of resistance in the mites against these chemicals.
2.      A new Bayer product Oberon (spiromesifen), which is a lipid biosysnthesis inhibitor and is known to work under low pest densities as per the product information of the company, was applied by the farmer. Hence, it is advisable to use a different insecticide/acaricide first to bring down heavy populations of the mite and then use this product for the second spray, if required.
3.      The numerous light yellow feeding patches caused by the mite on the leaves are irreversible. Therefore, absence of new colonies on unattacked leaves should be taken as the indicator of insecticide/acaricide efficacy.

II. White grub

            Although currently observed in a few acres, white grub may spread to newer areas. Since September-October is the end of the season and grubs would begin to pupate, plans should be drawn for integrated management in the forthcoming season.

Management practices

1.      In the current season, the effectiveness of clothianidin and Metarhizium anisopliae applied in the white grub affected farm should be monitored by post-treatment sampling. Grub numbers may decrease rapidly in the insecticide applied plot but the effectiveness of fungal treatment can be confirmed by collecting live grubs and maintaining in the laboratory for the development of infection. Since development of infection is a slow process, grubs are likely to pupate before the fungus can take over. However, the fungus applied in the current season may act as inoculum for the next season in view of its ability to survive in soil.
2.      It would be useful to dig the soil around drying or dried up clumps in the severely infested parts of the plot during September-October, collect the grownup grubs and kill them. This would reduce perpetuation of white grub in the next season.
3.      For the coming season, an integrated management strategy should be planned as outlined in the enclosed soft copy on white grub management.
4.      Since earlier trials indicated the usefulness of the fungus Beauveria brongniartii, this fungus may also be used in endemic areas as early season application and a prophylactic measure to immunize the soil for long-term control.

III. Scale insect

In our earlier visit to the same factory area in 2010, scale insect was noticed in about 100 ac area in a more severe form with predominance on varieties such as 92 R 62. In the present visit, another variety 83 R 23 was reportedly attacked by scale insect which indicated the possibility of the varieties from Andhra Pradesh being the source of inoculum or susceptibility. Currently, the pest did not seem to be as widespread as it was in 2010 despite its occurrence in a moderate form in the field visited. Such fluctuations indicate the possible disturbance of the equilibrium which may have rendered the crop susceptible to multiple biotic stresses as was observed in the field visited. Although currently restricted to isolated pockets, it is likely to be present in other areas too with varying levels of intensity. Regular monitoring of the crop in all divisions must be carried out from the fourth month age onwards to assess the status of the pest.

Management practices

1.      Avoid cultivation for a year or two of some varieties such as 92 R 62 and 83 R 23 showing consistent scale incidence in some pockets. Also, the occurrence or spread to other varieties needs to be monitored.
2.      Avoid ratoons in severely affected areas such as the field visited in the survey to prevent the spread of the pest to adjacent fields. Burning trash followed by deep ploughing as additional measures ensure destruction of inoculums colonies.
3.      Strict quarantine to be enforced to avoid the spread of suspected susceptible varieties or attacked plant material from the present farms for seed purpose.
4.      Apparently healthy seed material selected from the scale infested focal farms, either for planting in situ or elsewhere, should be subjected to treatment in 0.1% malathion for 15 minutes prior to planting.
5.      Similarly, if ratooning is inevitable in focal farms, stubble drenching with malathion or dimethoate or chlorpyriphos at 0.1% after stubble shaving should be carried out to prevent carryover of the pest.
6.      Detrashing should be made mandatory for a couple of years in the focal areas to deter pest proliferation under the leaf sheaths as well as facilitate plant protection.
7.      When regular monitoring indicates gradual buildup of the pest in the focal areas, high volume spray application should be resorted to early in 4 - 6 months old detrashed crop directing the fluid on the top internodes. Malathion, dimethoate, or chlorpyriphos at 0.1% or acephate at 0.15% should be applied. Insecticides may be alternated if repeated applications are needed.

IV. Pyrilla

            The sporadic outbreak of pyrilla in a couple of farms is not an exceptional instance since similar outbreaks were observed earlier. The situation would stabilize due to the exceptionally high activity of the parasitoid Epiricania melanoleuca. It is to be noted that pyrilla colonies comprise live insects and cast off skin (exuviae) adhering to leaf surface. Exuviae resemble live insects from a distance and give an erroneous impression of high pest density. Shaking or tapping the leaves drives away live stages and retains exuviae which gives a real picture of infestation levels.

Management practices

1.      The parasitoid Epiricania melanoleuca observed in high densities should be conserved and allowed to stabilize the host population. Hence, indiscriminate use of insecticides should be completely avoided.
2.      Since the farm has contiguous plots of crop with an age gradient, the younger crop should be monitored constantly for buildup of populations dispersing from the older crop. Early augmentation of the just initiating parasitoid populations in the younger crop would help the parasitoid to establish more rapidly and bring about the balance. To achieve this, leaves bearing live cocoons of the parasitoid, i.e. from which the adults have not yet emerged, should be collected from the older field, cut in to small bits of about 20 cm length, transported to the target field and inserted in leaf axils at different spots in the evening hours. Spraying should be avoided after parasitoid release. Progress of establishment of parasitoid and decline of host population should be monitored.
3.      Although the parasitoid is sure to follow the host if pyrilla spreads from the focal farm, it is essential to monitor the nearby farms for any possible outbreak of the pest. If pyrilla is noticed at high levels without parasitoid activity, a curative spray of dimethoate or acephate at 2 ml or g per liter may be given. After a gap of 10 days, parasitoid cocoons collected from the focal fields may be released to establish on the residual population and prevent their further buildup.

Senior Scientist (Entomology)
Sugarcane Breeding Institute, CBE

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