Field trials in 2011-2013 and a test market in 2013 conducted in corn and soybeans has confirmed what was claimed when Regalia Rx was registered, Marrone Bio Innovations announced.  

Adding one pint of Regalia Rx to an existing fungicide program improved overall plant health and yields. Applications of the product to both corn and soybeans produced plants with more extensive root systems, larger, fuller ears of corn, bigger and greener soybean plants and overall better yields, according to Marrone Bio Innovations. Similar yield response and plant health improvements were demonstrated in rice, wheat and barley trials during the same timeframe, according to the company.

"The average yield increase across the Regalia Rx trials conducted in conjunction with universities and on farms was six bushels an acre in corn and two bushels an acre in soybeans compared to the standard fungicide program," said Tim Johnson, Ph.D., global product development director for Marrone Bio Innovations. "These increases provide a very good return on investment on the pint of Rx that was applied."

Encouraged by the yield increases and plant responses that were observed, the product development staff focused a portion of the 2013 trials on comparing various application timing scenarios to see how application timing would impact product performance. The resulting data showed higher yield increases when Regalia Rx was applied earlier in the season.

In corn, studies showed that Regalia Rx applied at the V4 and V8 stages of growth boosted yields significantly more than later season applications at V8 and VT, explains Johnson.

The active ingredient in Regalia Rx is derived from a plant extract, and the company explains that it triggers plants' natural defense systems to help protect against disease, improve plant health, combat fungal and bacterial diseases and boost yield potential. Its mode of action is classified as induced systemic resistance (ISR). Marrone Bio says that ISR provides the crop benefits because of various reasons as explained.

  • Inhibits pathogen growth by:
    • Inducing phytoalexins and phenolic compounds
    • Increasing the activity pathogen-related (PR) proteins in plants
    • Elevating levels of reactive oxygen species (ROS)
    • Inhibiting spore germination
  • Strengthening cell walls
    • ISR increases the production of lignin in the plant (Note: Lignin is an organic substance that binds together cells, fibers and vessels within plant tissue. An increase in lignin in the plant adds to the thickness and strength of cell walls.)
    • This, in turn, helps plants resist pathogen attack more effectively
    • It also helps improve plant vigor and may reduce susceptibility to lodging
    • Promoting plant growth
    • Regalia Rx increases photosynthetic activities
    • It also stimulates the production of chlorophyll and phytohormones.

The product is synergistic with other fungicides. It is the only commercially available fungicide with a FRAC code of P5 so it adds another mode of action to a fungicide program, which has potential to improve overall disease control and plant health.

Mostly recommended as a foliar application (ground or aerial), Regalia Rx is also labeled for use as a soil treatment against soil-borne plant diseases. Trials comparing soil and foliar applications are in progress.   

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