Boscalid

Boscalid

啶酰菌胺

2-chloro-N-(4′-chlorobiphenyl-2-yl)nicotinamide

2-chloro-N-(4′-chloro[1,1′-biphenyl]-2-yl)-3-pyridinecarboxamide

188425-85-6

C₁₈H₁₂Cl₂N₂O

Fungicides > Pyridine fungicides
Fungicides > Anilide fungicides

BAS 510 is reported (International Mildew Workshop, 2002) to inhibit succinate-ubiquinone oxidoreductase (Complex II) in the mitochondrial electron transport system, leading to disruption of mitochondrial respiration and ATP production. In Botrytis cinereaand Monilinia laxa, BAS 510 produces inhibition of spore germination, whereas in other species, it induces reduced mycelial growth and spore development.

The mode of action is novel and BASF anticipates that BAS 510 will play an important role in disease resistance management. It is reported to be effective against organisms resistant to sterol inhibitors, dicarboximides, benzimidazoles, anilinopyrimidines, phenylamides and strobilurins.

The product provides broad spectrum preventative disease control through its inhibition of spore germination. Some curative effects are also observed due to the inhibition of germ tube growth and appressorium formation.

BAS 510 is a systemic fungicide and is transported acropetally in the xylem to the leaf tips and margins and also in a translaminar process, through the leaf tissues to the opposite leaf surface. Redistribution in the vapour phase is minimal.

Field evaluation studies conducted in 1998 with SC formulations indicated potential for control of dollar spot (Sclerotinia homoeocarpa) in creeping bentgrass (Agrostis palustris 'Penncross'), early blight (Alternaria solani) in tomato, and bean rust (Phaseolus vulgaris). The activity against early blight and the yield of tomato was similar to that provided by BAS 500 (pyraclostrobin). Trials in Tennessee in 2001 confirmed the potential for control of both early and late blight in tomatoes.

On legumes, BAS 510 controls white mould (Sclerotinia) and blight (Ascochyta). Control of white mould and early blight is achieved on potatoes. On peanuts, it is effective against Sclerotinia and other foliar pathogens. Trials in the US (Virginias and Carolinas) showed that Endura, applied at 14-21 day intervals, provided good control of blight and reduced the level of web blotch damage to less than 5%. BASF will recommend three preventative applications of Endura for blight control, starting 45-75 days after planting (depending on the region) and made at 14-21 day intervals. The product will integrate well into the current grower's disease control programme.

Trials in canola (oilseed rape) in North Dakota showed that BAS 510 (70 WP formulation) provided the best control of Sclerotinia and the best yield when applied in July at 20% bloom compared with the references (Benlate, Ronilan, Quadris, fluazinam, Flint). In Germany, BASF will launch boscalid for the control of Sclerotinia, Alternariaand Phoma.Applications can be made just prior to flowering to the full flowering stage (BBCH 59-69, optimally at 63-65), thus providing a good fit with existing BASF oilseed rape products such as Caramba (metconazole). The company reports that tank mixes will be recommended with Fastac (alpha-cypermethrin) and Nutribor (trace elements fertiliser). In France, boscalid (50% WP) gives good control of resistant Sclerotinia plus Alternaria spp and Phoma spp

The EPA fact sheet states that use of boscalid is prohibited on soybean, cowpea, field pea, lupin, sugar beet, garden beet, turnips and radishes. Furthermore, crops with registered uses may be replanted at any time while all other crops grown for food or feed may be replanted after 14 days.

The French INRA tested boscalid over two years (AFPP, 2003) on 800 isolates of Botrytis cinerea resistant to current fungicides and found no resistance issues. Boscalid was reported to provide efficacy equivalent to pyrimethanil (D0027L).

In 2008, The US EPA denied objections by the Natural Resources Defense Council (NRDC) over the establishment of tolerances for BASF's fungicide, boscalid. The NRDC challenged the EPA's December 2006 establishment of tolerances for leafy greens on the grounds that it had failed to apply an additional safety factor to protect the health of children. The NRDC claimed that the EPA should have applied the children's safety factor under the Food Quality Protection Act because young rats showed increased sensitivity to boscalid. The Agency concluded that the safety factor could be removed because the database was complete, there was a low risk of increased sensitivity in the young, and exposure had been estimated in a conservative fashion.

CropUses:
almonds, apples, apricots, arrowroots, aubergines, balsam apples, balsam pears, beet roots, beans, berries, bitter melons, blackberries, blueberries, brassicas, broccoli, Brussels sprout, bulb vegetables, cabbages, canola, cantaloupes, carrots, cauliflowers, chayotes, cherries, chickpeas, Chinese artichokes, Chinese cabbages, Chinese cucumbers, Chinese mustard, citron melons, collards, cucumbers, currants, dried peas, dry beans, edible cannas, edible gourds, elderberries, forage, fruiting vegetables, garlic, gherkins, ginger, ginseng, grapes, gooseberry, ground cherries, hay, hops, horseradish, huckleberries, Jerusalem artichokes, Kohlrabis, leafy vegetables, leeks, lentils, lerens, lettuce, loganberries, melons, mints, nectarines, oilseed rape (canola), onions, peas, peaches, peanuts, pears, pepinos, peppers, pistachios, plums, plumcotts, pome fruits, potatoes, prunes, pumpkins, raisins, raspberries, shallots, skirrets, soybeans, stone fruits, straw, strawberries, succulent beans, succulent peas, summer squashes, sunflower seeds, sweet potatoes, tomatillos, tomatoes, tree nuts, tumeric, turf, watermelons, winter squashes, vines, yams, yam beans

290-560 g ai/ha proposed for dried and succulent beans
500 g ai/ha recommended for oilseed rape (canola)
110-620 g ai/ha proposed for tomatoes, peppers, eggplant, potatoes
280-560 g ai/ha proposed for lettuce
330-500 g ai/ha proposed for peanuts
1200 g/ha recommended for grapevines
224-280 g ai/ha recommended for turf (control of dollar spot, Canada)

Pyrimethanil+Boscalid
Pyraclostrobin+boscalid
Kresoxim-methyl+boscalid
Epoxiconazole+boscalid
Dimoxystrobin+boscalid
Cyprodinil+Boscalid
Boscalid+Trifloxystrobin
Boscalid+Iprodione
Boscalid+Fludioxonil
Boscalid+Ethirimol
Boscalid+Cyprodynil
Boscalid+Azoxystrobin

Type	AI concn
Water-dispersible granule (WG)	50% (w/w)
Water-dispersible granule (WG)	70% (w/w)

Acute oral (rat)

LD50 >2,000

WATER SOLUBILITY: 4.6 mg/l at 20° C

Fate in aquatic systems:
Boscalid is stable to hydrolysis at environmentally relevant pH's (5, 7 and 9) and temperatures.
Boscalid is stable to photolysis in water; photodegradation is not expected to be a significant route of dissipation for boscalid in the environment.

Fate in soil:
Boscalid is stable to photodegradation on soil; photodegradation is not expected to be a significant route of dissipation for boscalid in the environment.
Boscalid is metabolized slowly in aerobic soils in the laboratory; while it's degradate 2-chloronicotinic acid is metabolized rapidly in such soils. The degradation of boscalid in aerobic soils was slow, with half-lives ranging from 96 to 578 days. The majority of the compound's apparent degradation is actually due to its transformation to bound residues rather than degradation or complete mineralization.
Boscalid is degraded very slowly in anaerobic soils in the laboratory. Valid half-lives could not be determined in either study since the degradation of boscalid did not reach 50% of the applied dose by the end of the study periods (120 days).
Boscalid is stable in anaerobic aquatic systems and metabolically stable in pond water/clay loam sediment systems In the total sediment:water system, [¹⁴C] boscalid decreased from 92.2-94.5% of the applied dose at day 0 to 49.7-51.8% at 179 days and 46.2-47.8% at 361 days. The calculated half-life (first-order linear) for the combined data was 385 days; DT50 (nonlinear) was 302-342 days. Degradation was not observed, and the reported half-life is not a true metabolic half-life. Disappearance of the parent was attributed to sediment binding.
Boscalid is stable in aerobic aquatic systems and metabolically stable in a water/German loamy sand sediment system and a water/German loam sediment system. No major degradates were detected in any of the systems. Half-lives were not calculated for the total systems since degradation of the parent was negligible.
Based on Koc values and the McCall classification scheme boscalid is expected to have low mobility in most soils and expected to bind to aquatic sediments. The boscalid degradate 2-chloronicotinic acid (M510F47) is expected to be very mobile in soil and is not expected to bind to aquatic sediments.
Based on terrestrial field dissipation studies, boscalid is generally persistent in the field, both in bare and cropped plots. The terrestrial field dissipation of boscalid was studied at several U.S. sites on various cropped and bare ground plots, and on bare ground plots in Canada. The DT₅₀'s for dissipation of the parent compound for boscalid applied to bare ground plots (U.S. and Canada) ranged from 27 to 372 days (generally greater than 100 days and frequently greater than 200 days). The DT₅₀'s for dissipation of the parent compound from the surface soil for boscalid applied to cropped plots (U.S. only; turf, peach, almond) ranged from 44 to >360 days and were generally greater than 100 days.
Environmental Fate Summary (from the US EPA Pesticide Fact Sheet):
Boscalid is persistent, it has low mobility in soil; however, boscalid may move to surface water through spraydrift and runoff of soil and suspended sediments. The degree of surface water contamination is mitigated by the relatively low seasonal application rates (2.1 lbs ai/acre/season) and its tendency to sorb to soil and sediment. The compound does not bioaccumulate appreciably in fish (BCF 35X-105X). The fungicide is practically nontoxic to terrestrial animals and is moderately toxic to aquatic animals on an acute exposure basis. Boscalid acute risk quotients (RQs) do not exceed acute risk levels of concern and is not likely to pose an acute risk to animals at the maximum use rate.
Boscalid is a slowly degradable compound with low mobility in most soils. The primary degradation pathway is aerobic soil metabolism, which proceeds slowly and results in the formation of intermediates which are relatively rapidly transformed into carbon dioxide or bound soil residues. The majority of the apparent degradation of the compound is actually due to its transformation to bound residues. Degradates of the compound include 2-chloronicotinic acid (M510F47), 2-hydroxy-N-4'-chlorobiphenyl-2-yl)-nicotinamide (M510F49), and an unknown (M5100F50).
The compound is not transformed to any significant extent in either aerobic or anaerobic aquatic systems, but is relatively rapidly transferred (dissipation half-lives of <2 weeks) from the water phase to the sediment phase.
Boscalid has low mobility in most soils, as it tends to adsorb to the organic matter. As such, it is likely to adsorb to aquatic sediments. Data from batch equilibrium studies, when considered along with results from Tier 1 computer models and terrestrial field dissipation studies, indicate a low potential for leaching. A slightly higher potential for leaching exists for the compound in soils which are low in organic matter content, as is often the case with coarse-textured soils.
There is a potential for boscalid to reach surface water through spray drift when applied using ground spray (multiple crops) or aerial spray (canola). The potential for overland surface runoff of the compound in the water phase is low, although it may occur due to the aqueous solubility of the compound. Also, because boscalid is generally persistent under field conditions, over time the compound may be present in field runoff as an adsorbed residue, and limited desorption of the bound parent compound from soil particles may occur in surface water bodies, particularly in soils with low organic matter content. The slow biodegradation of boscalid in most soils will increase the potential for both groundwater and surface water contamination.
The potential for groundwater contamination should be mitigated by the tendency of the compound to adsorb to surface soils, particularly those with relatively higher levels of organic matter. The potential for boscalid to leach in significant quantities or to reach surface water will also be mitigated by the low application rate (< 21b. a.i./A/season). Because boscalid does not biodegrade in aquatic systems, but does bind to sediments, the compound is expected to accumulate in the sediment phase of these environments. Results from Tier 1 models indicate that concentrations of Boscalid will be relatively low in groundwater and surface water, but that the compound will accumulate in surface water bodies.
The boscalid metabolite, 2-chloronicotinic acid, is very mobile in soil and is not expected to bind to aquatic sediments. However, it is metabolised rapidly in aerobic soil, and is mineralised to carbon dioxide or transformed to bound residues.
Boscalid is expected to accumulate in fish tissues at moderate levels, with greater accumulation in the non-edible tissue versus the edible tissue, but should depurate rapidly from the tissues when the fish are no longer exposed to the compound.
Exposure to aquatic organisms is expected to be limited due to the chemical's tendency to adsorb to sediments. Boscalid is moderately toxic to aquatic animals but based on estimated exposure concentrations, the proposed uses of boscalid are not likely to represent a threat of either acute or chronic ecological risk to freshwater fish and invertebrates or to estuarine/marine fish at maximum proposed multiple application rate of six applications of 0.350 lbs. a.i./A.
However, the acute risk level of concern for endangered species is exceeded for estuarine/marine invertebrates. While boscalid is not expected to adversely affect aquatic animals whose lives are primarily spent in open water, bottom-dwelling (benthic) fauna may be more likely to encounter boscalid based on the chemical's persistence and tendency to adsorb to sediments. Modelling of benthic exposure, based on a closed farm pond scenario over a 36-year period, did not exceed the chronic risk level of concern for sediment-dwelling animals.
Boscalid is categorized as practically non-toxic to birds on both an acute and sub acute exposure basis, no acute levels of concern (LOC) are exceeded for birds feeding on any of the modelled food items.

Hazard Class:O (Obsolete as pesticide, not classified)