Mar 31, 2021
Bio-pesticide gives growers a more flexible approach to nematode control

Image of tomatoes on the vine with OMEX logo on top of it

(Sponsored) Growers can free themselves from the sometimes restrictive cultural practices desirable for the control of damaging crop nematodes, says OMEX® Agrifluids, by adopting bio-pesticide treatments that won’t compromise organic certification.

Although effective to a degree, techniques such as crop rotation and variety selection can place a limit on flexibility and choice, says agronomist Francisco Rivera, because growers need to make those choices before the season.

“Nematodes are one of the most destructive crop pests we have to deal with,” he says, “thanks to their direct effect on the plant’s ability to absorb water and nutrients, and the secondary effects they cause by leaving the plant vulnerable to further attack by bacterial and fungal pathogens.

“Any nematode infestation has serious implications for growers of a range of crops from potatoes to vines, but this is amplified considerably in organic production.

“Staying true to organic principles, growers should always deploy cultural controls wherever they can,” he acknowledges. “But sometimes it seems like we expect growers to compromise on marketing opportunities by growing a less popular, but nematode-tolerant variety, or to over-complicate farm management through unwanted rotations.”

Familiar to ‘conventional’ US farmers for its often-novel crop nutrition products, OMEX® is becoming more widely known in organic circles for its growing stable of ‘developed for organic’ products, such as the OMRI-certified bio-fertilizer Achieve™ 3-1-3 — a highly effective, plant-derived plant growth enhancer.

OMEX® also turned to plant extracts for its bio-nematicide NemOMEX®, Rivera explains, which is derived from the bark of Quillaja saponaria, a tree native to Chile that’s also known as the soapbark tree.

“The name explains its effectiveness as a nematicide,” notes Rivera. “Nematodes have a notoriously impenetrable cuticle, yet the natural soap within Quillaja acts as a wetting agent, breaking down the cuticle and destroying the nematode’s first line of defense.

“Once it penetrates the cuticle, other compounds within the Quillaja extract have a direct biocidal activity on the nematode — it’s a natural, biological nematicide.

“We’ve identified more than 50 compounds in NemOMEX®,” Rivera notes, “a complex mix of different phytochemicals such as saponins, polyphenols, tannins, sugars and salts.

“Recent research shows that NemOMEX®’s mode of action is derived from the combination of these compounds, rather than any one active component.”

Results from several university-led laboratory and field trials, including Auburn University, the University of Arizona and Washington State University, have shown how Quillaja extract can deliver control and yields at a similar level to that of synthetic chemical nematicides, without the harmful effects on non-target soil organisms.

“One of the most attractive aspects of NemOMEX® is that its active ingredient has already been in use for nearly 20 years,” points out Rivera, “which demonstrates both its value and potential.

“Extensive studies have shown that it does not ‘tax’ the rhizosphere, the root zone of the plant that is directly affected by root exudation and soil microbes, and which plays a vital role in the plant-soil feedback loop.”

A side-by-side trial in potatoes examined the abilities of conventional nematicides against the performance of NemOMEX® for the control of nematodes common in the Pacific North-West: the root-knot nematode, which can leave tubers unmarketable; the stubby-root nematode, which has the same effect but also acts as a vector for tobacco rattle virus; and the lesion nematode, which causes direct tuber damage and enhances the severity of ‘potato early dying’ disease.

“All treatments were effective in their control of the nematodes,” observes Rivera, “with NemOMEX® increasing the percentage of clean tubers, with no nematode infection, from just 41 per cent in the control to more than 96 per cent. This performance was on a par with the conventional, synthetic nematicides.

“There were no significant differences between any of the treatments in yield,” he adds.

Before planning to use NemOMEX®, Rivera advises growers to consult their agronomist or adviser. “It’s suitable and effective in most crops where nematodes pose a threat, with three convenient application methods approved: ground spray, shank injection, or chemigation.

“Recommended dosage is between 1 and 2 qts/acre for light infestations, and up to 3gal/acre where control of a heavy infestation is sought.”

NemOMEX®’s OMRI registration number is OMX-11288.

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The product names and brands referenced here are registered and trademarks of OMEX® Agrifluids, Inc.

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