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Fomesafen Rotational Crop Intervals

By Aaron Hager

Nearly all herbicide labels (soil-applied or postemergence) have rotational crop intervals that specify the amount of time that must elapse between herbicide application and planting a rotational crop.  Adhering to these intervals is always important, but becomes particularly important with late-season herbicide applications or when soil moisture is limited.  These intervals are established to reduce the likelihood that herbicide residues will persist in sufficient quantities to adversely affect the rotational crop.  Some herbicide rotational restrictions are based solely on time, while other factors, such as soil pH and the amount of precipitation received after herbicide application, can influence the length of the crop rotational intervals.

Soil moisture is often the most critical factor governing the efficacy and persistence of soil-residual herbicides.  Many herbicides are degraded in soil by the activity of soil microorganisms, and populations of these microorganisms can be greatly depressed when soil moisture is limited.  Additionally, dry soils can enhance herbicide adsorption to soil colloids, thus rendering the herbicide unavailable for plant uptake and degradation by soil microbial populations.  Some herbicide rotational intervals are increased if a specified amount of precipitation is not received by a certain calendar date.

Diphenylether herbicides (Flexstar, Cobra and Ultra Blazer, for example) are routinely applied to soybean for control of waterhemp.  In non-GMO and glyphosate-resistant soybean varieties these herbicide active ingredients can provide good to excellent control of small, susceptible waterhemp, but control is often poor when waterhemp plants exceed 5–6 inches or are resistant to PPO-inhibiting herbicides.

Fomesafen has the longest soil residual activity among the three foliar-applied diphenylether herbicides.  Soil half-life values (the time required for half of the applied herbicide to degrade) for fomesafen have been reported to range from100 days to 6 to 12 months.  The range is dependent upon several factors, including soil type and soil moisture.  For example, the soil half-life of fomesafen under anerobic conditions (flooded soil) is only 3 weeks, but persistence is extended as soil moisture becomes more limited.  Labels of fomesafen-containing products (Table 1) specify 10 months must elapse between application and planting corn.  Applying a fomesafen-containing product at this time of the 2014 growing season would preclude planting corn before May 2015.
Table 1.  Fomesafen-containing products labeled in Illinois.
Andros
Battle Star
Battle Star GT
Camo
Cheetah Max
Dawn
Flexstar
Flexstar GT
Intimidator
Marvel
Matanza
Prefix
Rhythm
Ringside
Rumble
Shafen
Shafen Star
Soyafen
Statement
Top Gun
Torment
Vamos
Vise

Source: University of Illinois Department of Crop Sciences


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AJ Armstrong Takes the Helm as Manitoba Seed Growers President

Video: AJ Armstrong Takes the Helm as Manitoba Seed Growers President

The Manitoba Seed Growers Association (MSGA) held its first annual SeedLink Conference in Brandon last week, where a new president was appointed to take the helm of the organization.

A.J. Armstrong of Armstrong Seeds in Boissevain took the gavel from Past-President Tom Greaves. In a sit-down interview, Armstrong shared insights into his personal journey within the seed industry. Born into a family deeply rooted in seed cultivation, he took the reins of the family business in 2003, building on a legacy initiated by his father in 1980.

Regulatory modernization emerged as a significant focus of the conversation. While acknowledging the complexities of the process, Armstrong expressed optimism about the potential benefits for seed growers once the regulatory framework is finalized.

Discussing the dynamics of working with family in a business setting, he stressed the importance of open communication.

Operating with a streamlined team that includes his mom as the bookkeeper, his father as the “gopher” handling specific tasks, and a dedicated employee for day-to-day operations, the Armstrong family has successfully navigated the intricate balance of personal and professional relationships.

Open discussions about roles, responsibilities, and business plans contribute significantly to the smooth functioning of a family-operated seed business,” he said.

SeedLink is a new event; the decision to explore a return to a two-day annual meeting format sparked enthusiasm among industry partners, including key players and sponsors like SeCan, FP Genetics, Canterra Seeds, and numerous others.