Nitralin is a selective pre-emergent dinitroaniline herbicide[1] that is closely related to trifluralin, and released two years later in 1966. Today it is largely obsolete. It was used in the USA, France and Australia to control annual grasses and broad-leaved weeds, and was applied on vines, crops[2] [3] [4] and turf.[1]
American farmers used 405000lbs in 1974, though trifluralin still overshadowed it, with 22960000lbs.[5] A 1992 report mentions extensive use on potatoes,[6] though Shell's "Planavin" trademark expired in 1989.[7]
On ryegrass meristems, nitralin suppressed elongation and made the roots wider. After 1 hour, mitosis was reduced by 76%. Cell nuclei expanded, becoming polymorphic, and with increased ploidy levels. Other dinitroanilines have similar effects, except butralin.[8]
Nitralin is not associated with lung cancer.[4]
Planavin 75 was sold commercially as a wettable powder containing 75% nitralin, applied at around 2 pounds per acre (2.25 kg/Ha), equivalent to 1.5 lbs/acre of pure nitralin.[1] Shell sold technical grade nitralin at 94% purity for manufacturing purposes.[9]
Soil-applied nitralin is involatile; its vapours were below the limit of detection.[10] Water leaching is very slow. Together this makes nitralin immobile in soil, so application can be precise, though it cannot move far enough into soil to control deep-germinating weed species. Typical in-soil halflives are 30 to 60 days, and it decomposes under ultraviolet light.[11]
Ingested by rats, 98.5% is removed in 72 hours by urine and faeces. The metabolism is complex and produces many afterproducts.[12]
Compared to trifluralin, nitralin is more toxic to the roots and less toxic to the shoots. Trifluralin prevented emergence of most species tested; nitralin did not prevent any from emerging.[13] At Johnsongrass control, nitralin and pendimethalin lost out to trifluralin and other dinitroaniline herbicides.[14]
| Broadleaves Controlled[15] [16] | Grasses Controlled | Crops used on ! | Turfs used on | |
|---|---|---|---|---|
| amsinckia, amaranth, buckhorn plantain, bull mallow, carpetweed, common plantain, cress, curly dock (from seed), dead nettle, fat hen, fiddleneck, groundsel, henbit, knotweed, lambsquarter, mallow of Nice, munyeroo, pigweed, plantain, prickly lettuce, price-of-wales feather, purslane, pussley, shepherd's purse, smartweed | Annual bluegrass, annual ryegrass, brachiaria, burr grass, cheatgrass, crabgrass, cotton panic grass, cupgrass, downy brome, finger panic grass, goosegrass, green foxtail, ryegrass, johnsongrass, pigeon grass, setaria, watergrass, wild oats, winter grass, wireweed, witchgrass, yellow foxtail | bahia, bentcrass, bermuda grass, annual bluegrass, centipede, fescue, St. Augustine, zoysia, Japanese andromeda, Japanese holly, Azalea, boxwood, chrysanthemum, shasta daisy, ajuga |