Although metamine fumigants—sodium metam and potassium metam—have proven extremely reliable in controlling weeds, diseases, and nematodes in potato fields for more than four decades, recent discoveries have confirmed that there are several other uses for the product. to maximize efficiency.
New data on the movement of metames in the soil after application are somewhat "innovative". Many assumed that the movement of products up, down and sideways would be uniform over a distance of 6 to 12 inches. Another common assumption was that the product would remain in the soil, suppressing pests regardless of soil conditions.
In 2017, the author of the article began to wonder what was happening in the soil after the application of metham, when several Washington onion specialists began to wonder if the product was losing effectiveness. They didn't get the expected results. The author of the article purchased a miniRAE photoionization detector (PID) after learning about the technology from researchers at major universities and began field trips to measure the presence of metham at various soil depths for hours and days after application.
After three years of research, collecting more than 40 soil samples taken in various conditions, we found five main variables.
We call them the Five Pillars of metham movement in the soil. These new ideas are key to optimizing the effectiveness of metham fumigant application in soil.
Moisture retention
Maintain 80% moisture throughout the soil profile starting 30 days before application and after application if possible. Moist soil facilitates the movement of metames, promotes the respiration of pests, and helps preserve the product. Once soil moisture drops to 50 percent due to heat, wind, or excessive soil movement, readings will largely disappear within hours, not days. With this knowledge, we now understand the critical importance of pre-wetting.
Placement strategy
Compared to other fumigants, the vapor pressure of metham products is relatively low. They just don't spread as far or as evenly as those who have used it over the years have assumed. Test the soil to better understand the exact location of your pest. Then precisely place your metam product near the target pests by chemigation, stripping or deep stripping.
Equipment
Do not underestimate the minor adjustments to the equipment you use to prepare the soil, apply the product, and consolidate the application. It is possible to loosen the soil a little if you do not dry it out and leave the product on or near the surface of the soil.
Pest breath
Metam products are most effective when weed seeds, diseases and nematodes are respiring and thriving prior to product application. Too dry soil affects the respiration of pests. If you can't imagine that weed seeds actually thrive in a certain environment, then they probably don't and are much more difficult to suppress.
soil
Product movement may be limited by dry, compacted or cloddy soil. Avoid applying the product to deeply frozen ground. Anything you can do to keep the soil from drying out is critical.
Our results show that Metam products are as effective as ever. Nothing has changed in the effectiveness of the product itself. But when changes are made to application methods, using the five pillars as a guide, tangible improvements are possible. Each of the five pillars matters more, and we now have the data to back it up.