Professor Yunita T. Winarto, Universitas Indonesia
Professor James J. Fox, The Australian National University
Bimo Dwisatrio, Merryna Nurhaga, Nancy Kinanti, Universitas Indonesia
The three Districts (kabupaten) of Klaten, Boyolali and Sukoharjo form a single rice growing area. They constitute one of the most productive ‘rice baskets’ in all of Central Java with average rice production over 6 tons per hectare. A majority of these three districts is planted to rice three times a year, giving them a total annual planting area of well over 150,000 hectare.
Any serious threat to rice production in these districts can have a significant effect on Java’s production. This is what has been occurring with the continuing infestation of brown planthopper since the initial outbreak in Juwiring subdistrict in Klaten in the 1st planting season of 2009
By 2010, this hopper infestation had engulfed the neighbouring districts of Sukoharjo and Boyolali (see previous report). Crop losses in Sukoharjo exceeded those in Klaten and Boyolali. Sukoharjo thus became – and continues to be – the epicentre of a continuing outbreak.
It took until the second planting season of 2010 before serious infestations of virus began. These infestations were greater in Sukoharjo than in Klaten while there was initially only light infestation in Boyolali.
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By the second planting season of this year, virus infestations have increased to the point that they encompass a greater area of Klaten and Boyolali than the total area of local hopperburn whereas in Sukoharjo, there is still a greater area of hopperburn than virus infestation. However in both Sukoharjo and Boyolali, actual crop losses due to virus exceed losses to hopperburn.
In all three districts, virus infestation is a combination of grassy stunt virus (kerdil rumput) and ragged stunt virus (kerdil hampa), which is also described locally as ‘K.B.’, the initials for ‘family planning’ because the rice panicles are empty of grain).
Some farmers in the Klaten-Boyolali-Sukoharjo area are aware of the connection between the brown planthopper and virus infection. Many others, however, attribute infection to the soil itself or to recent weather conditions. Having been taught for decades that pesticides are ‘medicine (obat),’ farmers, even those who understand the cause of the virus, generally try to ‘cure’ their plants. They do this by increasing both fertilizer and pesticides. They often add both herbicides and fungicides to this mix.
When these efforts fail and without a proper understanding of the relation between the brown planthopper and subsequent infection, they just abandon their infected fields. Farmers rarely appreciate the need for complete eradication, nor after repeated crop failure, do they have the financial capacity to carry out eradication.
In cases of virus infection, the recommended policy is immediate eradication. This is one of the strong recommendations proposed for the entire Surakarta region in March 2011 as part of its RTL (Rencana Tindak Lanjut) strategy for dealing with the brown planthopper infestation.
In practice, however, without adequate resources and without a proper understanding of the advantages of eradication, farmers attempt to glean what grain they can from their infected fields and then sell the remaining stubble for cattle feed. This stubble can be transported well beyond the local area to neighbouring districts carrying with it remnant hoppers and their eggs.
Selling and transporting rice stubble from infected fields, especially when the incidence of virus is high as in the Klaten-Boyolali-Sukoharjo area at present, is a potent means of spreading and thus perpetuating virus infestation.
Harvesting a field for its stubble after virus infection does not necessarily clear a field. Remnant hopper populations can and frequently do remain in these fields. Often such fields are allowed to stand idle for a period before a portion of the field is made into a new seedbed for the next season’s planting. Where seed beds are established in partially cleared fields or in close proximity to such fields, the possibilities of virus infection are significantly increased. Evidence of virus can begin to occur in the seedbed itself but more often, it appears in the early stages of rice plant growth after transplanting. A high percentage of fields become infected from their own seedbeds.
A seedbed within a partial cleared field in the village of Wedi in Klaten that has already been seriously infected by virus. Virtually all the rice fields in the vicinity of this seedbed were infected with virus.
Farmers’ understanding is essential to the management of brown planthopper infestation. The provision of appropriate advice and the need for its dissemination is paramount in overcoming the present outbreak. Enhancing farmers’ knowledge and understanding is vital for the future.
Further related links
Operasi mandi pestisida (Operations Showering with Pesticides)
Wereng triangle and pesticide tsunami
Routine prophylactic spraying back in Indonesia
History repeats itself
Serious planthopper attacks in East Java