Phytol May Be Promising For Eco-Friendly Agrochemicals to Control Root-Knot Nematodes

Mar 23, 2021

Root-knot nematodes (RKNs, Meloidogyne spp.) infect a broad range of plants, including several agriculturally important species such as cotton, soybean and corn, as well as various vegetables and ornamentals. These parasites cause roots to develop galls that result in severe plant damage and, ultimately, important crop losses. Growers currently use synthetic nematicides to manage RKNs; however, these compounds are detrimental to the microbial diversity of soil and harmful for the environment. Thus, it is necessary to develop alternative sustainable control methods.

Root-knot nematode left

Root-knot nematode left; acid-fuchsin-stained RKNs in tomato root (center); gals formed by RKNs

"We have been seeking natural compounds that activate plant defense systems and do not have direct nematicidal activity using the combination of RKNs and their host plants," explained Shigemi Seo, researcher at the National Institute of Agrobiological Sciences of Japan. "We were most excited to discover that phytol, a chlorophyll constituent, has an inhibitory effect on the root invasion by a certain harmful plant nematode without killing it. We did not expect this molecule to be involved in RKN resistance."

"We noticed that plant leaves discolored yellow or pale green when their roots were parasitized by RKNs and confirmed a decrease in chlorophyll content in such leaves. We hypothesized that chloroplast-related compounds would accumulate in RKN-parasitized roots and induce the host defense against RKNs. We analyzed root metabolites and found accumulation of phytol, a constituent of chlorophyll. When phytol was applied to plant roots, RKN invasion of the roots was inhibited. This inhibition was not due to the direct nematicidal activity of phytol, since this compound did not kill RKNs," added Seo.

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Video: Western Canadian Agriculture: Hard Times Made the World's Best Farmers

Western Canadian agriculture produced the most advanced farmers in the world not through abundance but through adversity. The crow rate fell. The wheat price went nowhere. The brown envelopes stopped.

When the subsidies disappeared, the bad farmers left and the good ones stayed. And the ones who stayed could not just grow wheat anymore. They started growing lentils and canola and peas and flax and faba beans. They built crop rotation. They got serious about agronomy because there was no government backstop. That process produced the Western Canadian agriculture Dennis Bulani describes in this clip: the most advanced, most educated farming culture in the world.

His contrast with Iowa corn and soybean farmers is sharp. At a DeKalb farmer meeting in Okoboji, Iowa, he asked what crop rotation they ran. Beans on corn stubble, corn on bean stubble. How do you fertilize? The co-op agronomist handles it. Have you considered other crops? No need. We make so much money on corn and soybeans. Western Canadian agriculture was never allowed that comfort. And now those Iowa farmers are watching soybean markets lock up with China and corn prices slide, and they do not have the agronomy knowledge or the research base to pivot. Western Canadian farmers adapted on a dime because they had done it before.

Dennis also makes the case that Western Canadian agriculture keeps adapting in real time. Low commodity prices over the past year have pushed growers to look seriously at precision spot-spray technology. He knows a neighbor who bought a sprayer with the seeing-eye system and sprayed only 80 out of 320 acres. As a chemical retailer Dennis acknowledges that will affect his sales. He supports it anyway, because if it advances Canadian agriculture and makes farmers money, that is a good outcome.

The lesson Dennis draws from the tale of two farms: continuous improvement is the only durable strategy. When canola was $22 a bushel some growers went to Arizona instead of the Crop Production Show. When the price came down those same growers came back to the research and the discipline. Products do not go on Rack Petroleum's shelves unless they pass a replicated trial first. That is what Western Canadian agriculture built through hard times: farmers who do the work whether the times demand it or not.

Dennis Bulani is CEO of Rack Petroleum and Ultimate Yield in Biggar, Saskatchewan. Dan Aberhart hosts GTF Productions, Western Canadian Agriculture's foremost live briefing platform and its foremost AI training platform for ag operators