An ounce of prevention is worth a pound of late blight prevention in China

Photo: J. Zhang/AsiaBlight

Now in its seventh year, the AsiaBlight Network is committed to finding solutions to ward off and eliminate late blight disease, a pathogen that lays waste to 3-10 billion US dollars of potatoes annually around the world. Fungicides are the most common tool of defense against late blight, but these agrochemicals can cost up to 10-25% of the total value of a potato farmer’s harvest, thus reducing incomes and raising exposure risks for human and the environment. 

Central to this research is the research collaboration between the private and public sectors in China, which has led to many valuable insights that are being used to strengthen late blight prevention strategies. 

This year, Hebei Shuangji Chemical, a high-tech agricultural fungicide producer (and long-time collaborator with AsiaBlight) conducted some test demonstrations of various combinations of fungicides to find an optimal portfolio that is effective in controlling late blight while also less costly to farmers.  

The trials were held on plots at Yakeshi Senfeng Potato Company, located in the northeastern part of the country. As this region receives higher than average rainfall, the combination of fungicides recommended by Shuangji – with scientific guidance provided by the  CIP-China Center for Asia-Pacific (CCCAP) – anticipated these conditions and forecasted possible potato yields under these elements.  

The test featured 11-step application sequence with varying levels of proven and effective fungicides (details below). The application sequences were followed at three different sites at Senfeng Potato and the following results were recorded in September this year at the end of the growing season. Each “site” was 2 cubic meters.

Site Number of potatoes harvested weighing less than 150g Total cumulative weight (kgs) of potatoes less than 150g Number of potatoes harvested weighing more than 150g  Total cumulative weight (kgs) of potatoes more than 150g
1 21 1.68 31 6.88
2 55 3.62 34 6.54
3 24 1.94 51 11.36

These results were lauded by the team as largely positive and local farmers were invited to the testing site to learn about the application sequence and its effects on preventing late blight. Careful testing of amounts and percentages of fungicides will help regulate against overuse and keep farmers, their food, and the environment safe.  

But fungicides alone are not the answer to late blight prevention. AsiaBlight also focuses on detection and monitoring of potato plants to watch for lesion and other physical markers that can indicate presence of the disease at earlier stages. As in medicine so is true in agriculture… an ounce of prevention is worth a pound of cure. For potato farmers in China, and everywhere, the work of the AsiaBlight Network will help raise yields, boost nutrition and elevate incomes for farmers and markets alike.   

Photo: J. Zhang/AsiaBlight

Application sequence and fungicide amounts: 

  • 1st: 75% mancozeb water-dispersible granules or 60% pyraclostrobine-metiram 160g/ mu
  • 2nd: 70% fosetyl-aluminium·mancozeb 180g/ mu
  • 3rd: 72% cymoxanil mancozeb 165g/ mu
  • 4th: 75% mancozeb water dispersion or 60% pyraclostrobine-metiram 200g/ mu
  • 5th: 72% dimethomorph mancozeb 125g/ mu
  • 6th: 75% mancozeb water dispersion or 60% pyraclostrobine-metiram 200g/ mu
  • 7th: 68% metalaxyl mefenoxam·mancozeb 125g/ mu
  • 8th: 72% cymoxanil mancozeb 165g/ mu
  • 9th: 68% metalaxyl mefenoxam·mancozeb 125g/ mu
  • 10th: 72% dimethomorph mancozeb 140g/ mu
  • 11st: 70% fosetyl-aluminium·mancozeb 180g/ mu