Once produced by the DuPont company in the United States, Bladex was a herbicide used extensively to kill emerging broadleaf weeds and grasses in crop fields of peas, onions, potatoes, sweet corn, chickpeas and beans. By 2002, DuPont and the FDA (Food and Drug Administration) phased out the use of Bladex nationwide. It continues to be used in other countries although the World Health Organization cites concern over its effects on quality of drinking water.
The active ingredient in Bladex is a triazine chemical called cyanazine. It is water soluble and typically found in a white solid or powdery form.
Bladex is not toxic when used according to produce label directions, but is poisonous when absorbed through the skin. The chemical cyanazine does leach through soil, especially sand or loam types to penetrate and contaminate freshwater. Both underground water tables and surface lakes, ponds and streams receive traces of the chemical after rains and irrigation.
Bladex is used as a post-emergent herbicide to kill sprouting weeds, after the seeds or roots germinate and expose green stems and leaves to a height no greater than 3 cm (a little more than 1 inch). It demonstrates excellent effectiveness battling and killing infestations of broadleaf weeds and grasses. While Bladex applications did not harm desirable crops, over-application or ill-timed applications could cause foliage damage or death to crop plants unintentionally.
Since cyanazine does not persist in soil and leaches through, the effectiveness of the chemical in Bladex greatly diminishes in and is not recommended in sandy or sandy loam soils. Moreover, the dense particles in heavy clay soils also diminishes effectiveness. Therefore, although Bladex provided an excellent means to control an immense list of various weeds in crop fields, soil conditions affected its results. Simply put, only "perfect" soil conditions maximized its performance in killing weeds.
Effective weed control lasts from four to 10 weeks depending on soil temperature, soil moisture, soil microbial organisms, soil pH, and extent of soil leaching, according to the Bladex product label.
After being dissolved in water, Bladex is sprayed locally onto both small weeds' foliage and particularly the soil surface. For uptake of the chemical by plants, irrigation wets the soil to facilitate the penetration into the top few inches of soil for roots to absorb. Avoid application by aerial crop plane since overlap occurs and may result in harm to crops.