In August 2015, the first case of potato ‘white’ cyst nematode Globodera pallida (G. pallida) was detected in the Northeastern parts of Hokkaido, Abashiri. This region in Japan is famous for its starch potato fields and is a contender for being the area where the most potatoes are grown with the highest yield, as well as the largest volume of potatoes are shipped from within Japan.
Potato yellow cyst nematode Globodera rostochiensis (G. rostochiensis) was also detected in this region of Japan.
Since September 2015, soil inspection and tuber sampling inspection services were launched and implemented repeatedly in the region. The sampling inspection routine is to obtain samples from a potato variety resistant to G. rostochiensis, and then visually inspect any cysts clinging to roots.
As a result of these inspections, G. pallida was confirmed in 163 fields on 681ha (more than 10% of the inspected fields). Moreover, it’s been confirmed that approximately 10 years have passed since the first G. pallida nematodes first infested the fields.
In September 2016, an emergency control inspection was conducted based on plant protection law. The aim was to ensure complete eradication of this pest. Any transportation and planting of potatoes in the affected area were prohibited.
Since no potato variety resistant to G. pallida had been introduced to Japan, application of1,3-Dichloropropene and planting cover crops (tomato wild species; Solanum peruvianum L.) were the solution chosen to ensure eradication of the pest.
In 2018, 1,3-Dichloropropene was applied to 68 fields on 284ha and cover crops were planted in 79 fields on 265 ha. In 28 fields (131ha), the eradication strategy was in essence “twice application of 1,3-Dichloropropene and one cover crop planted”, or “one application of 1,3-Dichloropropene and two cover crops planted in succession”.
1,3-Dichloropropene is not approved in Europe and other countries. Although 1,3-Dichloropropene is approved in Japan, the application of 1,3-Dichloropropene has its challenges, including a safe method for its eventual disposal.
Abashiri is a famous fishery city for – amongst others – salmon fishing. Some of the potato fields where G. pallida was detectedare located quite near an important river in this city. In consideration of this, a new method of eradication is now under consideration.
Granular nematicides – of which Nemathorin (fostiazete) and Nemakick (imicyafos) are available in Japan – are applied to infected fields that are located within 500 meters from the river, instead of the the application of 1,3-Dichloropropene in combination with cover crops as a strategy. In addition, appropriate crop rotations and the introduction of resistant potato varieties are done continuously.
The successful management and eventual eradication of PCN in Japan has two crucial challenges: Namely to find a balance between complete and efficient eradication of G. pallida on the one hand, and an environmentally responsible way to do just this – whilst taking into account the interests of all stakeholders involved. This might not be an easy goal to accomplish, but one worth striving for, no doubt…
Sources: Press release, related government regulations, and minutes of a recent review meeting arranged by the Japanese Ministry for Agriculture, Forestry and Fisheries.
Author: Mariko Kihira, owner of the consulting company maru communicate based in Japan, operating globally.
Mariko can be reached at email@example.com