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Researchers at a uni­ver­sity in south­west China have dis­cov­ered a new root-knot nema­tode species in the vine­yards of Yunnan province.

The sci­en­tists from Yunnan Agricultural University still can­not say whether Meloidogyne vitis is more dan­ger­ous than other species of the wide­spread and deadly plant par­a­site.

“We con­sider M. vitis to be of an equal threat as other root-knot nema­todes,” Yang Hu, a researcher at Yunnan Agricultural University, said last month. ​“Whether there are cer­tain char­ac­ter­is­tics [that] make it par­tic­u­larly vicious, we don’t know yet, and fur­ther research will also be nec­es­sary.”

“We need to iden­tify root-knot nema­tode species so that we can carry out tar­geted con­trol pro­grams to bet­ter pro­tect vine­yards,” Hu added.

As a species, root-knot nema­todes are par­tic­u­larly per­ni­cious and are one of the top three eco­nom­i­cally-destruc­tive plant par­a­sites. The nema­todes spread via run­ning water, ani­mals and through the trans­porta­tion of infected plants or plant mate­ri­als.

The root-knot nema­tode is not host-spe­cific, with some species attack­ing more than 3,000 dif­fer­ent types of plants, includ­ing olive trees.

Together with cit­rus root nema­todes, root-knot nema­todes are his­tor­i­cally respon­si­ble for losses of five to 10 per­cent of olives in the United States – with the lat­ter account­able for five per­cent of global crop dam­age.

When the researchers col­lected roots and soil from local vine­yards, they found 90 per­cent of the roots were infected with root-knot nema­todes.

After study­ing the sam­ples they had col­lected, the sci­en­tists then dis­cov­ered that the par­a­site had per­cep­ti­bly dis­tinct fea­tures from other root-knot nema­tode species. After fur­ther research, they iden­ti­fied it as a sep­a­rate species.

The researchers at Yunnan found that the roots of grapevines affected by M. vitis at first exhib­ited slight swelling and then began to rot. This impacted the qual­ity of the grapes and led to sig­nif­i­cant reduc­tions in yields.

In olives, dam­age caused by root-knot nema­todes varies slightly in each tree’s roots and is influ­enced by fac­tors such as soil tex­ture.

Root-knot nema­todes can adversely affect the size of olives and one of the vis­i­ble signs is sickly-look­ing trees con­cen­trated in some areas of an olive grove. However, the dam­age caused by the par­a­sites is not always easy to iden­tify.

Rising tem­per­a­tures, increas­ing car­bon diox­ide lev­els and chang­ing sea­sons asso­ci­ated with cli­mate change are pre­dicted to accel­er­ate the nema­todes’ life cycles.

• Courthouse News
• Olive Oil Source
• American Phytopathological Society