Jong Ham, LSU AgCenter plant pathologist, inspects soybean plants at the LSU AgCenter Plant Material Center. The plants are grown from seeds treated with biostimulants and inoculated with pathogens to see how the biostimulants protect the plants from diseases. Photo by Tobie Blanchard

Plant pathologists are often focused on bad bacteria — the ones causing disease in plants. Jong Hyun Ham, however, is looking at good bacteria to help grow better soybean plants.

Ham is conducting research on biological materials that can encourage disease resistance and enhance soybean growth and yields.

He said these biostimulants can cause a good reaction in the plants, boosting immunity to challenges they might face in the field similar to how a vaccine can prevent illness.

“It could be put directly on the plant or used as a seed treatment. I am interested in seed treatments,” Ham said. “It is more efficient and potentially safer.”

With seed treatments, a farmer wouldn’t have to spray the chemical or biological agent in the field, which would reduce runoff and keep it from reaching non-targeted plants.

Ham starts the process by screening bacteria from the soybean fields and isolating strains. He also screens the individual bacteria cells and selects strains based on their possible beneficial activity to the plant’s growth.

“Some bacteria produce plant growth hormones, so we identified those bacteria and tested the bacteria on the plant growth,” he said.

Ham has been investigating the use of biostimulants on soybean plants and rice for about five years. This year his research will expand to priming the seed — treating the seed with the chemical or biological agent as opposed to spraying the plant. He said priming makes the plants ready to respond to challenges in the field such as pathogens.

“We are testing different chemical material known to induce plant defense,” he said. “The difference with some previous research is to test if priming protection can be obtained by the seed treatment.”

Plants growing from primed seeds won’t appear much different from non-primed plants. The growth and yield will be similar, but Ham said if a pathogen infects the field, the plants grown from primed seeds will be more likely to exhibit elevated resistance or less disease symptoms.

Ham said in his research he has seen that treating soybean seeds with salicylic acid or methyl jasmonic acid enhanced resistance of soybean seedlings to the fungal pathogen Rhizoctonia solani, which can cause root and stem rot.

“The plant shows resistance to rhizoctonia, and they might be resistant to other pathogens,” he said.

Ham is developing additional research with AgCenter plant pathologist Vinson Doyle to look at how the seed priming may work against Cercospora.

Ham said he conducted similar studies in rice using chitosan, a component of shellfish, and said the compound induced plant protection.

One challenge Ham is facing is the shelf life of the formulations he is developing.

“The bacteria are a living organism, so it is challenging to preserve it.”

He is freeze drying the bacteria cultures and testing the stored formulas at different time periods to see how they perform.

Ham expects to continue the study for a few years to test different combinations and formulations of the biostimulants and compare his products with commercially available ones. Ham said because he is using common material, his formulas would be less expensive than what’s currently on the market.

“Hopefully we get a cheaper option to enhance soybean resistance to diseases,” he said. Tobie Blanchard