PESTICIDE RESIDUES IN FOOD - 1984
Sponsored jointly by FAO and WHO
EVALUATIONS 1984
The monographs
Data and recommendations of the joint meeting
of the FAO Panel of Experts on Pesticide Residues
in Food and the Environment and the
WHO Expert Group on Pesticide Residues
Rome, 24 September - 3 October 1984
Food and Agriculture Organization of the United Nations
Rome 1985
PROPAMOCARB
IDENTITY
Chemical Name (IUPAC and C.A.): Propyl 3-(dimethylaminopropyl)=
carbamate C.A. Registry No. [67338-67-4]
Synonyms: PREVICURRN, PREVEX, FILEX, BANOL, DYNONE N
Schering Code Nos. SN 66752 and ZK 66752
Structural Formula: CH3 O
\ "
N - (CH2)3 - NH - C - O - C3H7
/
CH3
Molecular formula: C9H20N2O2
Information on identity and properties of the hydrochloride salt,
C9H21C1N2O2
Molecular weight: 224.7
State: The technical hydrochloride salt is a
colourless, very hygroscopic crystalline solid
with a faint aromatic odour.
Melting point: 45-55°C
Vapour pressure: 6 × 10-6 Torr at 25°C
Dissociation
constant (pKa): 9.1
Octanol/water
partition
coefficient: 2.5 × 10-3
Solubility (at 25° C) >700 g/l in water; >500 g/l in methanol;
>430 g/l in methylene chloride; >300 g/l in
isopropanol; 23 g/l in ethyl acetate; <0.1 g/l
in toluene and hexane.
Stability: Propamocarb hydrochloride is very stable to
hydrolysis. Even at pH 14 the half-life is 5
days. At pH 9 the half-life was calculated to be
1.3 × 103 years, increasing at pH 5 to 1.3 ×
107 years. The product is stable at 55°C for
over 2 years, and to light, even on the addition
of acetone.
Technical material and impurities
The technical material has a purity in excess of 95% of the
hydrochloride salt.
The main impurities are as follows:
N,N-dimethyl-1,3-diaminopropane dihydrochloride max. 5%
N,N-bis(3-dimethylaminopropyl)urea dihydrochloride max. 2%
Solvents max. 1%
Formulation: "PREVICUR N" is an aqueous solution containing 722 g/l
propamocarb hydrochloride a.i.
RESIDUES IN FOOD AND THEIR EVALUATION
USE PATTERN
Propamocarb is available only as the hydrochloride. It is a
systematic fungicide especially active against Oomycetes fungi of the
genera Pythium, Aphanomyces, Phytophtera, Peronospora,
Pseudoperonospora and Bremia causing damping-off, root and stem rot,
leaf blight, fruit rot and downy mildew. It is applied as a preventive
soil drench or by soil incorporation, seed dressing, dipping of bulbs
and roots or foliar spraying.
The meeting was informed that propamocarb as hydrochloride is
registered and sold in more than 30 countries (Table 1).
Pre-harvest treatments
Propamocarb is formulated only as 72.2% hydrochloride in aqueous
solution. This formulation is used for foliar application as well as
for seed dressing, soil drenching and soil incorporation.
Post-harvest treatments
No recommendations have been reported for post-harvest uses of
propamocarb.
Other uses
Propamocarb is approved for use on ornamentals in many countries
and also for use on tobacco and turf.
Table 1. Registrations and approved uses of propamocarb
Approved application rate
Country Commodity Applications Pre-harvest
formulation containing 72.2% interval
propamocarb hydrochloride a.i.
Austria 1 Vegetables 0.15-0.25%:5 l/m2 5.4-9.0 g/m2 Seedbed drench na
Cucumbers 0.25%:3 l/m2 5.4 g/m2 Post-seeding drench cucumbers-
0.15%:0.2 l/plant 0.22 g/plant Post-plant drench 2 weeks
(repeat after 4 weeks)
Lettuce 2 2 l/ha 1.44 kg/ha Several sprays beginning lettuce -
10 days after planting 3 weeks
(10-14 day intervals)
Strawberries 0.2% 144 g/hl Pre-plant dip
0.5 ml/plant 0.36 g/plant Two sprays after
planting ns
(4 week intervals)
Bulgaria Peppers 0.15-0.2% 4.3-5.8 g/m2 Post-seeding drench na
0.15-0.2% 0.27 g/plant Post-plant drench ns
Chile Sugar beet 40 ml/kg 28.8 g/kg Seed treatment na
Colombia Soybeans 0.5-2 ml/kg 0.36-1.44 g/kg Seed treatment na
Czechoslovakia 1 Vegetables 0.15% 108 g/hl Seedbed drench na
Cucumbers )
Tomatoes ) 0.15%:100 ml/plant 0.22 g/plant Drench ns
France 1 Vegetables ) 14 ml/m2 10.1 g/m2 Drench ns
Strawberries) 300 ml/m3 217 g/m3 Soil incorporation
Table 1. (continued)
Approved application rate
Country Commodity Applications Pre-harvest
formulation containing 72.2% interval
propamocarb hydrochloride a.i.
German Tomatoes 0.15%:4 l/m2 4.3 g/m2 Pre-plant drench ns
Democratic 1 0.15%:0.2 l/plant 0.22 g/plant Post-plant drench
Republic
German Lettuce 3 1.5 l/ha 1.1 kg/ha Spray (max 3 lettuce -
Federal applications 3 weeks
Republic1 Cucurbits ) 0.15%:6 l/m2 6.5 g/m2 Pre-plant drench
Tomatoes ) 0.15%:0.2 l/plant 0.22 g/plant Post-plant drench ns
Greece 1 Vegetables 0.15%-0.25% 108-180 g/hl Seedbed drench
0.15%:100-300 0.22-0.66 g/plant Drench ns
Cotton 20-40 ml/kg ml/plant 14.4-28.8 g/kg Seed treatment
Hungary 1 Sugar beet 20 ml/kg 14.4 g/kg Seed treatment na
Vegetables 0.3-0.4 l/m3 217-289 g/m3 Soil incorporation vegetables -
0.15-0.25% 108-180 g/hl Drench 60 days
Israel 1 Cucumbers 0.15% 108 g/hl Drench ns
Italy 1 Vegetables 10-40 ml/kg 7-29 g/kg Seed treatment vegetables -
8-12 ml/m2 5.7-8.7 g/m2 Pre-plant drench 20 days
0.2%:0.1-0.2 l/plant 0.14-0.29 g/plant Post-plant drench
1.5-3 l/ha 1.1-2.2 kg/ha Foliar spray
Jordan 1 Vegetables 4 0.15% 108 g/hl Pre- and post-plant ns
drench
Malaysia 1 Vegetables 5 0.16% 116 g/hl Seedling root soak
0.16%:2 l/m2 2.3 g/m3 Post-plant drench
0.16% 116 g/hl Spray (at 5-7 day ns
intervals)
Table 1. (continued)
Approved application rate
Country Commodity Applications Pre-harvest
formulation containing 72.2% interval
propamocarb hydrochloride a.i.
Netherlands 1 Cucumbers) 0.1%:5 l/m2 3.6 g/m2 Pre-plant drench na
Tomatoes ) 0.1%:0.25-0.5 l/plant 0.2-0.4 g/plant Post-plant drench ns
Cauliflower 0.5 l/1000 m2 0.36 g/1000 m2 Seedbed spray
Peru 1 Vegetables 0.25%:2-4 l/m2 3.6-7.2 g/m2 Seedbed drench
0.15%:6-10 l/m2 6.5-10.8 g/m2 Pre-plant drench na
0.15-0.2%:6-8 l/m2 6.5-11.6 g/m2 Post-plant drench ns
Rumania Sugar beet ) 20 ml/kg 14.4 g/kg Seed dressing na
Cucumbers )
Peppers )
Tomatoes ) 0.15-0.25% 108-180 g/hl Post-plant drench ns
Cucumbers )
Onions ) 0.15% 108 g/hl Spray ns
Cucumbers )
Spain1 Cucumbers 250-300 ml/m3 181-217 g/m2 Soil incorporation cucumbers
0.25%:6 l/m2 10.8 g/m2 Post-seeding drench 3 weeks
5-7.5 ml/m2 3.6-5.4 g/m2 Seedbed drench
0.15%:100 ml/plant 0.11 g/plant Post-plant drench
Strawberries 0.3-0.5% 216-360 g/hl Preplant dip strawberries -
0.15%:100 ml/plant 0.11 g/plant Post-plant drench 6 weeks
Switzerland 1 Vegetables 2-20 ml/kg 1.44-14.4 g/kg seed treatment na
0.25%:2-4 l/m3 3.6-7.2 g/m2 Post-seeding drench
0.15%:5-10 l/m2 5.4-10.8 g/m2 Post-pricking-out drench
Table 1. (continued)
Approved application rate
Country Commodity Applications Pre-harvest
formulation containing 72.2% interval
propamocarb hydrochloride a.i.
Lettuce 0.15%:3-6 l/m2 3.2-6.5 g/m2 Post-pricking-out drench
0.15%:5-10 l/m2 3.2-6.5 g/m2 Pre-plant drench
1.5-2 l/ha (0.15%) 1.08-1.44 kg/ha Spray, 2 weeks after lettuce -
planting 3 weeks
(at 2 week intervals)
Thailand Tomatoes )
onions ) 0.15-0.25% 108-180 g/hl Seedbed drench na
United 1 Edible 10 ml/m2 7.2 g/m2 Seedbed drench
Kingdom crops 6 0.4 l/m3 289 g/m3 Compost incorporation edible crops -
0.15-0.2%:0.1 l/plant 0.11-0.14 g/plant Drench 14 days
Notes: na = not applicable
ns = not specified
1 Approval for ornamentals not included
2 Approval includes use in greenhouses
3 Not approved under glass
4 Cucumbers, tomatoes and watermelons
5 Tomatoes, cabbage, cucumbers, lettuce and watermelons
6 Brassicas, celery, cucumbers, leek, marrow, melons, onions, peppers, spinach, strawberries and tomatoes
RESIDUES RESULTING FROM SUPERVISED TRIALS
Residues of propamocarb have been determined in a variety of
plant products following soil incorporation, soil drench, seed
dressing and foliar treatments. Trials have been carried out by
Schering AG in many countries representing different climatic
conditions on a wide range of food crops. All residues in the
supervised trials are expressed as propamocarb hydrochloride.
Detailed lists of the residues resulting from supervised trials
are presented in Tables 2 to 6. The commodities analysed are grouped
according to the classification adopted by the CCPR.
Results from trials are underlined when they are in accordance or
approximately in accordance with approved uses and (when applicable)
with the recommended withholding periods in the country in which the
trial was performed.
Root and tuber vegetables, A01.0100 (Table 2)
Red and sugar beets. Mature red and sugar beet roots were analysed
for residues of propamocarb after seed treatment at 10.89 g/kg seed.
Red beets were treated additionally with a 0.18% drench immediately
after seeding. Residues at harvest were below the limit of
determination (<0.2 mg/kg and <0.05 mg/kg for red and sugar beets
respectively.
Radishes. Radishes grown as second crop following tulip cultivation
under glass in soils treated with 5.2 g/m2 and 11.2 g/m2 a.i. showed
residues of 0.8 and <0.05 mg/kg after 86 and 99 days, respectively.
Radishes treated first with a seed dressing (7.2 g/kg seed) and later
with two drench treatments at high dosage rates (2 × 36.1 kg/ha or
2 × 54.2 kg/ha) resulted in relatively high residues of 9.1 and
7.6 mg/kg after 9 - 14 days and 3.7 and 6.6 mg/kg after 18 - 21 days.
When the drench treatments were at lower rates (0.65 or 0.72 kg/ha) or
the radishes were sprayed at 0.72 kg/ha, the residues ranged from 3.4
to 0.2 mg/kg after 9 - 14 days and from 2.8 to <0.2 mg/kg after
18 - 21 days.
Bulb vegetables, A01.0200 (Table 2)
Leeks Leeks were sprayed after transplanting with 0.11%
propamocarb. The residue level 25 days after treatment was 4.1 mg/kg.
Leafy vegetables (except brassica vegetables), A01.0300 (Table 3)
Endive. Following spray application with 0.11% propamocarb
hydrochloride, residues in endive ranged from 0.4 mg/kg to 2.3 mg/kg
after 15 days, and from 0.5 to 0.6 mg/kg after 25 days.
Table 2. Supervised residue trials with propamocarb on root, tuber and bulb vegetables
Application method and rate (a.i.) Residues (mg/kg) / Days after final application
Commodity Country Year Seed Soil in- Drench Spray
dressing corp. % % 0 9-14 18-21 25-30 39-40 50 80-90 90-100 > 100
g/kg g/m2 (kg/ha) (kg/ha)
Red Beet Switzerland 1979 10.8 <0.2
0.18 <0.2
Sugar Beet Finland 1979 10.8 <0.05
Radish German 1976 5.2 0.8
Federal 11.2 <0.05
Republic
1979 7.2 (2x36.1) 61 9.1 3.7
(0.65) 2.8 0.4
(2x0.65) 1.1
7.2 (0.72) 1.8 0.2
1980 7.2 (2x54.2) 3.7 0.4 <0.2
7.2 (2x54.2) 39 7.6 6.6
7.2 (0.72) 25 3.4 0.2
7.2 (0.72) 48 0.3 <0.2
Leek Italy 1981 0.11 4.1
Table 3 Supervised residue trials with propamocarb on leafy vegetables (except brassica)
Application method and rate (a.i) Residues (mg/kg) / Days after final application
Commodity Country Year Soil Drench Spray
incorporation 0 4-7 14-15 17-21 24-33 47-50 60-63 70 80-83 > 100
g/m (g/m2) g/m2 % (kg/ha)
Endive Italy 1981 0.11 0.4 0.6
0.11 2.3 0.5
Lettuce German 1976 ( 5.2) <0.05
Federal ( 7.5) 0.5
Republic (11.2) 0.05
(GFR)
Netherlands 1977 2x0.04 (0.36) 4.0
0.07+0.04 0.2
France 1977 2x0.04 4.0 2.8
0.07+0.04 5.4 4.1
Belgium 1977 2x0.04 0.3
0.07+0.04 0.2
France 1977 180 2.5
180 0.12 (1.16) 1.5
2x0.12 (1.16) 0.15
3x0.12 (1.16) 0.05
GFR 1977 2.2 0.5
2.2 0.05
3x0.07 (0.87) 0.75
5.4 0.05
5.4 2x0.07 (0.87) 0.1
Austria 1977 7.2* (3x1.81+1x0.65)* 13
(3x0.43)* 1.2
(4x0.43)* 54
Table 3 (continued)
Application method and rate (a.i) Residues (mg/kg) / Days after final application
Commodity Country Year Soil Drench Spray
incorporation 0 4-7 14-15 17-21 24-33 47-50 60-63 70 80-83 > 100
g/m (g/m2) g/m2 % (kg/ha)
GFR 1977 (3x1.44) 26 6.8 4.8 1
Lettuce GFR 1977 3x0.04(0.36-0.54) 7 4.5 2.5
3x0.07(0.72-1.08) 17 8.5 4
3x0.11(1.08-1.62) 9.5 5.5 2
3x0.14(1.44-2.17) 30 17 6
GFR 1977 3x0.07 (1.44) 23 7.2
GFR 1978 3x0.07 (1.08)* 62 43 11.1 2.5
Austria 1978 7.2* (1x1.44)* 8
7.2* (2x1.44)* 6
7.2* (3x1.44)* 6 3
7.2* (4x1.44)* 13 13
(2x1.44)* 3
(3x1.44)* 7
(2x1.44)* 2
Table 3 (continued)
Application method and rate (a.i) Residues (mg/kg) / Days after final application
Commodity Country Year Soil Drench Spray
incorporation 0 4-7 9-15 17-23 24-34 39-40 78-83 90-93
(g/m3) g/m2 % (kg/ha)
Lettuce GFR 1978 (3 x 1.08)* 45.4 21.7 19.7 2.6 6.1
(3 x 1.08)* 30.9 14.5 6.8 4.9 1.3
(3 x 1.08)* 49.2 20.8 5.3 1.5
GFR 1978 (3 x 1.08) 66.2 10.7 1.1 0.4 0.4
(3 x 1.08) 35.3 6.3 2.3 0.4
GFR 1978 (3 x 1.08) 44.3 10.4 7.7 1.6
(1x0.72+3x1.08) 43.3 6.3 0.9 0.4
UK 1978 6.25 8.6
4x0.07 1.1
France 1977 108 2.2
144 3.2
180 3.1
GFR 1978 (3 x 1.08)* 11.3 7.5 8.7 1.5
Denmark 1978 7.2* 6.3
0.07 (1.81)* <0.1
0.07 (1.81) 1.1
7.2* 2.6
1x0.07 (1.81)* 0.5
2x0.07 (1.81)* 2.6
3x0.07 (1.81)* 15
Table 3 (continued)
Application method and rate (a.i) Residues (mg/kg) / Days after final application
Commodity Country Year Soil Drench Spray
incorporation 0 4-7 9-15 17-23 24-34 39-40 78-83 90-93
(g/m3) g/m2 % (kg/ha)
France 1978 180* 0.6
217* 0.1-0.2
253* 0.3
1979 217* 0.6 0.1
GFR 1978 (3 x 1.08)* 62 43 38 19
1979 (3 x 1.08)* 50 18 7.4 7.3
(3 x 1.08)* 38 12 6.7 2.7
(3 x 1.08)* 58 25 17 11
(3 x 1.08)* 49 39 25 14
(1x0.72+3x1.08) 70 42 18 13
Table 3 (continued)
Application method and rate (a.i) Residues (mg/kg) / Days after final application
Commodity Country Year Soil Drench Spray
incorp. g/m2 4-8 9-15 17-23 24-35 37-40 42-50 55-63 70 73-83 90-93 >100
g/m3 (g/plant) % (kg/ha)
Lettuce Austria 1979 9+(0.2)* 1.8
9+(2x0.2)* 1.7
(1x1.44)* 15 11 1.6
(1x1.44)* 55 30 3
0.15* (3x1.44)* 18 9.7
(3x1.5)* 12 7.2
(3x1.5)* 8.3 4.4
5.4* (3x1.5)* 36 27
5.4* (3x1.5)* 28 21
(3x1.44)* 20 11
(2x1.44)* 18
(3x1.44)* 21 8
Italy 1980 10.8 3.9 5
Denmark 1980 7.2* 1.4 6.3 5.1
7.2* 4.3 4.6 3.5
7.2* 3.1 3.3 2.3
7.2* 5.3 2.3
UK 1981 210 0.4
280 0.1-0.5
420 1
560 1
210 1.6
210 0.7
280 0.7
Lettuce France 1981 182 0.1
217 0.1
Table 3 (continued)
Application method and rate (a.i) Residues (mg/kg) / Days after final application
Commodity Country Year Soil Drench Spray
incorp. g/m2 4-8 9-15 17-23 24-35 37-40 42-50 55-63 70 73-83 90-93 >100
g/m3 (g/plant) % (kg/ha)
GFR 1981 217 0.3 <0.1 <0.1
217 0.1 <0.1 <0.1
7.2 (1x1.08) 15 2.2 0.1 <0.1
217 <0.1 <0.1 <0.1
Denmark 1979 (1x1.4)* 11
1.4* 0.2
(2x1.4)* 9.3
(1x1.4)* 2
1.4* 0.2 0.3 <0.1
(1x1.4)* 34 14
Application method and rate (a.i.) Residues (mg/kg) / Days after final application
Commodity Country Year Seed Spray
dressing 0 7 10-11 14 21-22 28-30
g/kg kg/ha
Spinach German 1978 14.4 2 x 0.72 19 2.2 3.1 2.3
Federal
Republic 1979 14.4 2 x 0.72 33 9.7 6.9 3.7
14.4 2 x 0.72 71 16 3.8 2.0
14.4 2 x 0.72 42 22 6.5 6.0
1980 14.4 2 x 0.72 36 1.5 <0.2 <0.2
* Application in greenhouses
Table 4. Supervised residue trials with propamocarb on brassica leafy and stem vegetables
Application method and rate (a.i.) Residues (mg/kg) / Days after final application
Commodity Country Year Soil Drench Spray
incorporation % 12-40 56-76 88-98 118-147 170-174 196-231
g/m3 mg/plant (kg/ha)
Brussels UK 1978 108 <0.2
sprouts 217 0.8
866 0.6
1979 108 <0.05
217 <0.05
108 0.13
217 0.05
108 <0.05
217 <0.05
2 x 0.11 2.2
144 <0.05
144 <0.05 <0.05
144 <0.05
144 <0.05
Cabbage UK 1978 181 <0.05
1979 108 <0.02
217 <0.02
108 0.02
217 0.06
Cauliflower UK 1978 217 0.05
1979 2 x 108 <0.05
1 x 108 <0.05
2 x 217 <0.05
1 x 217 <0.05
Table 4. (continued)
Application method and rate (a.i.) Residues (mg/kg) / Days after final application
Commodity Country Year Soil Drench Spray
incorporation % 12-40 56-76 88-98 118-147 170-174 196-231
g/m3 mg/plant (kg/ha)
2 x 108 <0.05
1 x 108 <0.05
2 x 217 <0.05
1 x 217 <0.05
Netherlands 1982 (2 x 1.08) <0.1
(2 x 2.17) 0.1
1983 (1-3x2.17) <0.1
(1 x 3.61) <0.1
(2 x 3.61) 0.17
(3 x 3.61) 0.14
Celery UK 1978 2 x 250 1.1
3 x 250 0.1
3 x 250 0.2
Italy 1981 0.11 2.7
Table 5. Supervised residue trials with propamocarb on fruiting vegetables - edible peel
Application method and rate (a.i.) Residues (mg/kg) / Days after final application
Commodity Country Year Soil Drench Spray
incorporation mg/plant % 0-3 4-7 9-14 19-21 26-38 40-62 68-79 82-97 140
g/m3 (g/m2) (kg/ha)
Cucumbers Sweden 1977 542 1.4
361 1.5
181 1.1
Spain 1978 361 0.3
2 x 181 0.3
2 x 361 0.8
722+361 <0.1
181 <0.1
181+361 <0.1
2 x 361 <0.1
Sweden 1978 2 x 361 2.0 0.9 0.6 0.7
Denmark 1978 5 x 181 1.3 0.8 0.4
GFR 1979 (4.3+0.2) 0.4 <0.1
(6.5+0.2) <0.1 <0.1
(8.7+0.3) <0.1 <0.1
Israel 1979 361 <0.05
Austria 1979 (9)+217 1.8
(9)+2x217 1.7
Switzerland 1981 (2x9)+361+722 0.6
(2x9)+361+2x722 0.8 0.4 0.4 0.2
(2x9)+361+144 0.07 1.4 1.2 0.5 0.5
Table 5. (continued)
Application method and rate (a.i.) Residues (mg/kg) / Days after final application
Commodity Country Year Soil Drench Spray
incorporation mg/plant % 0-3 4-7 9-14 19-21 26-38 40-62 68-79 82-97 140
g/m3 (g/m2) (kg/ha)
Greece 1981 3x0.14 1.7 1.0
Netherlands 1983 90 DI* 0.1-0.8 0.8 0.3 0.1
180 DI 0.5-0.8 1.9 0.7 0.1
720 DI 0.1-3.3 3.5 1.1 0.1
Cucumbers GFR 1983 (8x2.17) 0.9-1.5 0.6 0.5
(8x2.17) 0.8-1.2 0.9 0.8
Peppers GFR 1977 32+108 0.1
65+217 0.2
130+433 0.25
France 1978 181 4x217-1083 0.22(dip) <0.2
4x217-1083 0.22(dip) <0.2
5x217-1083 <0.2
Italy 1980 (10.8) <0.05
Netherlands 1983 108NFT** <0.02 <0.01 0.1 0.2
217NFT <0.01 0.2 0.4 0.9
866 NFT 0.2-0.5 0.3 0.5 1.7
Table 5. (continued)
Application method and rate (a.i) Residues (mg/kg) / Days after final application
Commodity Country Year Drench
mg/plant 0-3 4-7 10-14 19-21 26-38 40-62 68-79 82-97 101-119
(g/m2)
Tomatoes GFR 1978 (3.25) <0.05
(2x3.25) <0.05
(2x3.25)+217 <0.05
1979 (4.33)+144 0.10 0.08 0.06
(6.50+0.54) <0.05 <0.05 <0.05
Denmark 1979 108 0.09 0.05
GFR 1979 (8.66+0.90) <0.05 0.26 0.17
Italy 1980 722 <0.1 0.23
1444 0.29 <0.1
(10.8) <0.1 1.9
(10.8) 0.57 <0.1
Netherlands 1983 90 DI* 0.05 <0.05 <0.05 <0.05
180 DI 0.06 <0.05 0.06 <0.05
720 DI 0.05-0.4 0.2 0.2 0.4
108 NFT** <0.05 <0.05 <0.05 0.05
217 NFT <0.05 0.06 0.3 0.3
866 NFT <0.05 0.8 0.5 0.6
Notes: * DI = Drip Irrigation
* NFT = Nutrient Film Technique
Table 6. Supervised residue trials with propamocarb on miscellaneous crops
Application method and rate (a..i) Residues (mg/ks) / Days after final application
Commodity Country Year Soil Seed Drench Spray
treatment treatment mg/plant mg/plant 36-39 60 70-78 101-105 126-132 230-272 278-305 328-370
g/m2 g/kg (%)
Melons Italy 1980 722 <0.05
1444 <0.05
Pumpkins Italy 1980 722 0.08
1444 0.21
10.8 <0.05 <0.05
Apples Italy 1981 2x8.7 <0.05 <0.05
Strawberries GFR 1977/78 722 <0.05
2x361 <0.05
722+361 <0.05
GFR 1977/78 940 <0.05
2x940 <0.05
2x470 <0.05
722 0.1
2x361 <0.05
2x722 <0.05
Belgium 1979/80 722 <0.01 0.02
722 <0.01 <0.01
722 <0.01 <0.01
Italy 1980 722 0.43
1444 1.3
UK 1978-80 (2x0.14) <0.02
(2x0.29) <0.02
Table 6. (continued)
Application method and rate (a..i) Residues (mg/ks) / Days after final application
Commodity Country Year Soil Seed Drench Spray
treatment treatment mg/plant mg/plant 36-39 60 70-78 101-105 126-132 230-272 278-305 328-370
g/m2 g/kg (%)
Rapeseed GFR 1980/81 7.2 <0.05 <0.05
7.2 <0.05 <0.05
7.2 <0.05 <0.05 <0.05
Lettuce. A number of different application methods are used in
lettuce cultivation with spray applications always giving the highest
residue levels. Multiple sprayings of propamocarb in the field at
1.1 kg/ha (the approved rate for the Federal Republic of Germany,
except in greenhouses) resulted in residue levels after 21 days (the
recommended withholding period) ranging from 0.4 mg/kg to 13 mg/kg.
When spray applications were conducted under glass, residues 21 days
after final application increased up to 25 mg/kg following 3 sprays at
a rate of 1.1 kg/ha and up to 11 mg/kg at a rate of 1.44 kg/ha (the
approved rate in Austria).
Soil incorporation of propamocarb HC1 gave considerably lower
residues, up to 3.2 mg/kg after 80 days.
Soil drench applications also resulted in lower residues than
spray treatments, up to 6.3 mg/kg 18 days after drenching.
Spinach. Combined seed dressing (14.4 g/kg seed) and spray
applications (2 × 0.72 kg/ha) to spinach gave residues on day 0 after
final application of 19-71 mg/kg; days 10-11, 1.5-22 mg/kg; days
21/22, <0.2-6.9 mg/kg and days 28/30, <0.2-6.0 mg/kg.
Brassica (cole) leafy vegetables, A01.0400 (Table 4)
Brussels sprouts. Drench application to Brussels sprouts at rates
up to 866 mg/plant gave residues ranging from <0.05 mg/kg to
0.8 mg/kg, 196 - 231 days after treatment.
Two spray treatments with 0.11% propamocarb hydrochloride
resulted in a residue of 2.2 mg/kg, 28 days after the final
application.
Cabbage. In cabbage treated with 108 - 217 mg/plant by drench, only
minimal residues (<0.02 mg/kg to 0.06 mg/kg) could be found 65 - 118
days after application.
Cauliflower. Soil incorporation or drench treatments of
cauliflowers resulted in residues near or below the limit of
determination (0.05 mg/kg) at harvest. Multiple spray applications up
to 3.6 kg/ha gave a maximum residue of 0.17 mg/kg, 26 days after the
final application.
Stem vegetables, A01.0500 (Table 4)
Celery. Multiple drench applications to celery at 250 mg/plant
resulted in a maximum residue of 1.1 mg/kg, 98 days after the last
treatment.
A single spray application at 0.11% propamocarb hydrochloride
resulted in a residue of 2.7 mg/kg, 25 days after treatment.
Fruiting vegetables - edible peel, A01.0700 (Table 5)
Cucumbers. Multiple drench applications to cucumbers at rates up to
722 mg/plant or 8.7 g/m2 gave the following maximum residue levels:
0-3 days, 1.4 mg/kg; 4-7 days, 2.0 mg/kg; 9-14 days, 1.7 mg/kg;
19-21 days, 0.6 mg/kg; 26-38 days, 1.5 mg/kg and 40-62 days,
1.8 mg/kg.
Multiple spray treatments with 0.14% propamocarb hydrochloride
resulted in a residue of 1.7 mg/kg three days after the final
application and 1.0 mg/kg 10 days after the last spraying. Eight
sprayings with 2.17 kg a.i./ha gave the following residue levels:
0-3 days, 0.8-1.5 mg/kg; 4-7 days, 0.6-0.9 mg/kg; 9-14 days,
0.5-0.8 mg/kg.
Drip irrigation at 90 mg/plant (the highest rate recommended for
disease control) gave residues of 0.1-0.8 mg/kg at 3 days, 0.8 mg/kg
at 7 days, 0.3 mg/kg at 14 days and 0.1 mg/kg at 21 days after
application.
Peppers. Multiple drench treatments of peppers up to 1083 mg/plant
results in low residue levels of 0.1-0.25 mg/kg, 40-62 days after
application. In peppers treated with propamocarb using the nutrient
film technique at 108 mg/plant (the highest rate recommended for
disease control) residues were <0.01-0.2 mg/kg.
Tomatoes. Multiple drench applications to tomatoes at rates up to
10.8 g/m2 or 1444 mg/plant gave residues of <0.05-0.57 mg/kg at
68-79 days after the final application and <0.05-1.9 mg/kg at
101-119 days.
Residues observed in trials using 90 mg/plant as a drip
irrigation or 108 mg/plant in the nutrient film technique (the highest
rates recommended for disease control) did not exceed 0.05 mg/kg
during the 21 day pre-harvest interval.
Fruiting vegetables - inedible peel, A01.0800 (Table 6)
Melons. Residues in melons treated by drenching with 722 or
1444 mg/plant were below the limit of determination (<0.05 mg/kg),
36 days later at harvest.
Pumpkins. Soil treatment of pumpkins with 10.8 g/m2 gave no
detectable residues (>0.05 mg/kg), 70 days after application.
Drenching with 1444 mg/plant resulted in a residue of 0.21 mg/kg
39 days later at harvest.
Pome fruit, A02.1000 (Table 6)
Apples. In apples treated twice with 8.7 g/m2, residues could not
be determined (<0.05 mg/kg) 78 days after application.
Small fruits and berries, A02.1200 (Table 6)
Strawberries. Spray applications to strawberries at rates up to
2 × 940 mg/plant did not lead to residues exceeding 0.1 mg/kg after
230-370 days.
Drench treatments with 722 and 1444 mg/plant resulted in residues
of 0.43 and 1.3 mg/kg, respectively, 60 days after application. In
another trial (UK, 1978-1980) no residues (<0.02 mg/kg) could be
determined 271 days after drench application.
Oilseed, A05.2000 (Table 6)
Rapeseed. Seed treatment of rapeseed with 7.2 g/kg propamocarb
hydrochloride did not give any detectable residues (<0.05 mg/kg) at
harvest.
FATE OF RESIDUES
General
Studies have been carried out on lettuce and tobacco, soil and
water. For discussions on the metabolic fate of propamocarb in the
rat, see "Biochemical aspects" in the evaluation for ADI. No feeding
studies have been performed on cattle or poultry as no uses of
propamocarb on crops used for animal feedingstuffs have been approved.
Studies have also been made on bioaccumulation in fish.
In soil
The behaviour of propamocarb hydrochloride in soils was
investigated by studies of leaching, tested by column leaching and
adsorption/desorption experiments; dissipation and degradation in a
variety of soil types and under different conditions in the laboratory
and field; the effect on soil microorganisms; uptake by rotational
crops.
Leaching. Studies show that the leaching of propamocarb
hydrochloride is very dependent on the soil type. The migration of
propamocarb hydrochloride residues to deeper soil layers was tested by
column leaching and adsorption/desorption experiments on the following
German standard soils:
pH organic carbon clay + silt (%)
(%) (<0.02 mm)
2.1 loamy sand 5.5-7.5 0.25-0.75 <10
2.2 loamy sand 5.5-7.5 2-3 10-20
2.3 sandy loam 5.5-7.5 0.5-1.5 20-30
No propamocarb or degradation products were found in the
leachates from columns filled with standard soils 2.1, 2.2 or 2.3
after irrigation with 200 mm of artificial rain water. Examination of
some columns, however, revealed that the fungicide was not entirely
immobile, since the bulk of the material had moved to a depth of
8 - 20 cm in standard soils 2.1 and 2.2. This is consistent with the
Freundlich adsorption constants determined for standard soil 2.2
(5.83) and a river bottom sediment (1.26). (Ottnad, 1978a; Brühl,
1979d; Brühl and Celorio, 1979a).
Leaching tests on 4 different soils including German standard
soils 2.1 and 2.2, conducted according to EPA guidelines, showed that
even extended irrigation with 600 mm of water over a period of about 6
days did not cause penetration of most soil columns used except those
consisting of standard soil 2.1, from which 50 to 60% of the applied
ingredient was found in the leachate (Brühl, 1978a).
After aging for 30 days in standard soil 2.2, most of the applied
propamocarb hydrochloride had been mineralized. Upon irrigation with
12.5 mm water for 45 days, only 10-15% of the original material was
recovered, the main part being absorbed by the first 5 cm of the
columns. Less than 2% of the fungicide was found in the leachate.
Under the same conditions the behaviour of propamocarb hydrochloride
in standard soil 2.3 was quite different. Only about 20% of the parent
compound was eventually mineralized, 38 to 48% appeared in the
leachate and the rest was evenly distributed over the entire soil
column. This is somewhat surprising since another soil (California
loamy sand), similar in organic carbon content and texture, exhibited
a much greater adsorption capacity. It seems therefore that besides
distribution between soil solution and organic matter, other
mechanisms such as ion exchange exert an important influence on the
leaching behaviour of propamocarb hydrochloride (Brühl, 1978a; Brühl
and Celorio, 1979b; Meallier et al., 1983)
Metabolism. Laboratory tests under aerobic conditions to determine
rates of dissipation and metabolic pathways have been performed with a
variety of soil types. Depending on the microbiological activity of
the soil samples, adaptation phases of 5 days to 8 weeks were
necessary before breakdown of propamocarb commenced. After such lag-
periods, however, dissipation was rapid with half-lives ranging from
10 to 27 days. This process, which usually followed biphasic first-
order kinetics, was always accompanied by fast mineralization of the
molecule as indicated by the high rates of 14CO2-evolution which
reached as much as 90% after 45 days. (Brühl, 1979b; Brühl and
Celorio, 1978 and 1980b; Ottnad, 1977c and 1978b). Lowering of the
ambient temperature from 25° to 15° had no significant effect upon the
degradation rates (Brühl and Celorio, 1980a).
Field studies conducted in Germany (Berlin-Frohnau) and the
United States (Wonder Lake, Illinois; Cantonment, Florida; Blackstone,
Virginia and Tifton, Georgia) have shown that the laboratory tests
reflect field behaviour; in all cases the estimated half-lives were in
the range of 2 to 3 weeks (excluding adaptation phases) (Jenny, 1980a
and 1980b; Ottnad, 1977a, b).
Intermediate metabolic products were observed in all tests
carried out with 14C-labelled material. These compounds occurred in
small quantities (less than 3% of originally incubated 14C-label),
indicating that their decomposition was at least as fast as that of
the parent molecule. Identification of the intermediates was not
feasible (Brühl, 1979b; Brühl and Celorio, 1978, 1980a, b).
Studies with sterilized and non-sterilized soil as well as mixed
populations of soil microorganisms have confirmed that, under aerobic
conditions, the observed breakdown of propamocarb is brought about by
microbial action (Iwan, 1979 and 1980).
Simultaneous application of propamocarb hydrochloride and other
pesticides to soil had inhibitory as well as stimulating effects on
aerobic microbial degradation (Fournier et al, 1981).
Laboratory tests under anaerobic conditions were conducted with
German standard soil 2.2 and with river bottom sediment. In standard
soil 2.2, dissipation was very slow with a half-life (calculated
according to first-order kinetics) of 459 days (Brühl, 1979c).
A biphasic dissipation process following zero-order kinetics
(both phases) was observed with river bottom sediment. The half-life
of propamocarb under these conditions was 55 days. Substantial
14CO2-evolution, measured up to the 60th days of the experiment,
indicated that oxidative degradation mechanisms must still have been
operative during the first phase of decomposition. Intermediate
metabolic products again occurred in small quantities (up to 4
compounds, each less than 5% of the originally incubated 14C-label)
but could not be identified (Brühl and Celorio, 1980c).
Effect on soil microorganisms. Studies conducted with freshly
collected silty clay and sandy loam soils showed that propamocarb
hydrochloride concentrations of 3 and 30 mg/kg had no significant
effect on carbon turnover or nitrogen fixation. Sulphur oxidation was
slightly stimulated at both levels. For protein deamination and
nitrification, a minor short-lived depression (less than 14 days) was
noted at 30 mg/kg (Hughes, 1981).
Uptake by rotational crops. In a rotational crop study loamy sand
soil was treated with 14C-labelled propamocarb hydrochloride (3 mg/kg
dry weight). After aging periods of 30 and 120 days soybeans, sugar
beets and oats were sown. Crops were harvested at quarter, half and
full maturity and leaves, stems, roots and fruiting parts were
analysed separately. In all aerial parts of all crops (both ageing
periods) residues were less than 0.3 mg/kg. Residues in sugar beets
were always below the detection limit (0.04 mg/kg). Residues in
soybeans and oats grown in soil after 30 days ageing appeared somewhat
higher (up to 0.3 mg/kg) than those in crops grown after an ageing
period of 120 days. Because the residues were so low no identification
was possible.
Analysis of soil samples taken at the same intervals as the crops
showed rapid degradation of the extractable residues. After 169 days
in the 30-day-experiment and 245 days in the 120-day-experiment about
10% remained in the soil as non-extractable material.
In view of the rapid degradation of propamocarb hydrochloride in
the soil and the low or undetectable residues in all crops at normal
harvest, virtually no residues are to be expected in rotational crops
grown under field conditions in practice (Brühl, 1979a).
In Plants
The metabolism of propamocarb hydrochloride in plants was
investigated in lettuce after spraying and in tobacco treated by
drenching.
Metabolism in lettuce. Studies were conducted to determine the
nature of the residues after spraying with propamocarb hydrochloride
with a 3-dimethylamino-[1-14C]-propyl label. Three to nine percent of
the total residues remained as non-extractable material. Residues in
the extracts were determined by one- and two-dimensional TLC. 60-85%
consisted of unchanged parent compound up to 36 days after the last
application. Up to 17% consisted of five degradation products which
were not identified. Four of these were more polar and the fifth less
polar than the parent compound. Further investigations have shown that
they included artefacts formed during the analysis at the extraction
stage. It was later shown that the artefacts varied between 3 and 56%
of the total recovered radiolabelled compounds when no precautions
were taken. When special care was taken the proportion was 5-17%. It
was concluded that under optimized analytical conditions only 10-15%
of the total residue would escape detection because of artificial
breakdown and formation of non-extractable material. The residue
analysis of lettuce therefore need only be for the unchanged parent
compound (Brühl, 1980, 1981a, b).
Metabolism in tobacco. Tobacco plants, treated at the 6-8 leaf
stage by drenching with 300 ml of radiolabelled 0.3% aqueous
propamocarb hydrochloride solution, took up considerable quantities of
the fungicide via the root system. Much of this material was
translocated acropetally to the extent that radioactivity was detected
in the uppermost leaves and flowers. With respect to distribution, a
propamocarb hydrochloride concentration gradient of the order of 100:1
(from bottom to top) was observed, i.e. the residue levels in the
oldest tobacco leaves were 50 - 200 times higher than those in the
youngest leaves and the flowers. The meeting was informed that in
later experiments, TLC and GC/MS analysis of the plant extracts showed
that all residues consisted of the unchanged parent compound. Curing
of the tobacco leaves had no effect on the residue composition. Only
about 1% or less of the radioactivity in the tobacco plants was
non-extractable by the methods employed (Brühl, 1978b).
The distribution of propamocarb in tobacco plants after uptake
via the roots indicates that the fungicide is partly systemic.
A possible explanation for the lack of metabolic conversion in
the plant species investigated may be that phase-I reactions
(detoxifying processes) are not needed, since propamocarb has little
phytotoxic effect. Phase-II reactions (conjugation), usually aimed at
enhanced water solubility of xenobiotics and thus better storage in
cell vacuoles, appear equally unnecessary in view of the virtually
unlimited water solubility of the compound.
In animals
No feeding studies have been performed on cattle or poultry as no
uses of propamocarb on crops used for feeding of animals have been
approved.
In fish
Bluegill fish (Lepomis macrochirus) were exposed to 0.1 mg/l of
[14C]-propamocarb hydrochloride in a flow-through system for 28 days
followed by a 14-day depuration period. [14C]-propamocarb
hydrochloride equivalents in fillet tissue ranged from less than
0.5 mg/kg at 10 days to a maximum of 1.70 mg/kg at 14 days. In offal
tissue, residues ranged from 1.83 mg/kg at day 1 to 3.42 mg/kg at day
7.
Channel catfish (Ictaluras punctatus) were exposed to water
containing soil, into which had been incorporated [14C]-propamocarb
hydrochloride at 3.0 mg/kg, in a static system for 28 days followed by
a 14-day depuration period. The level of radio-carbon in the hydrosoil
decreased from 2.60 mg/kg after one day to 1.28 mg/kg after 28 days,
whilst levels in the water ranged from 0.013 mg/l at day 1 to
0.029 mg/l at day 28. [14C]-propamocarb hydrochloride equivalents in
fillet tissue ranged from 0.098 mg/kg at day 1 to 1.16 mg/kg at day
28, and in offal tissue from 0.16 mg/kg at day 1 to 1.08 mg/kg at day
28.
In both species, radioactivity was rapidly lost from tissues when
the fish were transferred to untreated water or water/soil systems.
Bioconcentration factors for fillet and offal tissues were 1.5 and 3.0
for bluegill and 39.9 and 43.0 for channel catfish, respectively. The
biological half-life of radioactive residues was less than seven days
in all cases (Gray and Knowles, 1980).
Both bluegills and channel catfish received intraperitoneal
injections of [14C]-propamocarb hydrochloride at a level of
2.25 mg/kg. Elimination of radioactivity was rapid in both species
with more than 77% of the dose present in the water within 24 hours.
Compounds from this water were separated by TLC. Besides unchanged
propamocarb, which was the main compound, they included three unknown
metabolites. Residues in the fish 24 hours after administration were
highest in the bile in both species. In both fillets and offals
unchanged propamocarb was the main compound and three metabolites were
also present. Small amounts of a compound which co-chromatographed
with 3-dimethylaminopropylamine were also observed (Gray and Knowles,
1981).
In water
Hydrolysis. Hydrolytic breakdown of propamocarb hydrochloride is a
base-catalyzed process which proceeds at extraordinarily low rates.
Even at pH 14 at 25°C, a half-life of about 5 days was measured. The
temperature dependence of the rate constant strictly followed the
Arrhenius equation with the activation energy EA amounting to
17.57 kcal/mol. Assuming pure base catalysis, the rate constants and
half-lives shown in Table 7 were obtained by extrapolation to pH 9, 7
and 5 at 25°C.
Table 7. Rate constants and half-lives of propamocarb in water
pH k1 (min-1) t1/2 (years)
9 1.05 x 10-9 1.26 x 103
7 1.05 x 10-11 1.26 x 105
5 1.05 x 10-13 1.26 x 107
Propamocarb hydrochloride is stable in acid aqueous solution. No
indication of hydrolysis was detected after exposure to pH 1 at 70°C
for 3 days (Repenthin, 1976).
Photolysis. Following 92 hours of irradiation at wavelengths above
290 nm and a light intensity of 2250 Jm-2 sec-1, the decrease of the
initial propamocarb hydrochloride concentration in aqueous solution
was no greater than in corresponding non-irradiated controls. This is
to be expected, since the compound does not absorb light energy from
the environmentally relevant part of the spectrum. The addition of
acetone did not produce any measurable photosensitising effect (Klehr,
1978). Additional studies have shown that the observed decrease of the
propamocarb hydrochloride concentration in irradiated as well as
non-irradiated solutions was due to microbial activity (Klehr, 1980).
Biological decomposition. In mineral salt solutions containing
acetate as a carbon source and spiked with a few drops of original
lake water, propamocarb hydrochloride was rapidly degraded after a
lag-phase of two weeks. On the 35th day of the test, more than 30% of
the originally incubated fungicide was mineralized and the amount of
parent compound had dropped to 3%. Several metabolic products were
detected in the culture medium. However, as these compounds did not
accumulate, and therefore occurred only in low quantities (usually
less than 5%), they could not be identified. In samples lacking an
additional carbon source, virtually no decomposition of propamocarb
hydrochloride took place. The most prominent genus amongst the
microorganisms identified in the culture medium was Pseudomonas
(Iwan, 1983).
METHODS OF RESIDUE ANALYSIS
Analytical methods to detect and quantify propamocarb residues in
plants, soil and water are designed to determine the unchanged parent
compound only, because only very small amounts of metabolites have
been observed in these materials. Residues of propamocarb in plant and
soil samples are determined by GLC using a thermionic detector
operating in the nitrogen-specific mode.
The compound is extracted with 0.1 N-hydrochloric acid, and
cleaned up by partitioning with chloroform and di-isopropyl ether. The
free base is quantified by GLC. As the compound is very polar a column
of carbowax 20M + 0.5% KOH on chromosorb 750 may be used. The limit of
determination is 0.1 mg/kg in most crops (König and Ottnad, 1977;
Noach, 1978; Jenny, 1979; Scheuermann, 1983).
Residues in water are extracted with di-isopropyl ether after the
addition of sodium hydroxide and measured without further clean-up
(König and Ottnad, 1977a).
NATIONAL MAXIMUM RESIDUE LIMITS
National maximum residue limits from a number of countries were
reported: (Table 8).
Table 8. NATIONAL MAXIMUM RESIDUE LIMITS
Country Commodity MRL Pre-harvest interval
(mg/kg) (days)
France Lettuce 5.0
Cucurbit 1.5
Tomato, pepper,
strawberry 0.5
Federal Republic
of Germany Lettuce 15 21
Cucurbit, tomato 0.5
Hungary Vegetables 0.5 60
(soil drenching)
Italy Vegetables 10 20
Netherlands Fruiting vegetables
cauliflower 0.1
Switzerland Cucurbits 1.5
Lettuce 10 21
APPRAISAL
Propamocarb is a systemic fungicide especially active against
Oomycetes fungi causing damping-off, root and stem rot, leaf blight,
fruit rot and downy mildew. It is registered and used in more than 30
countries.
Propamocarb is formulated only as 72.2% hydrochloride in aqueous
solution and all experimental data and application rates are quoted in
terms of propamocarb hydrochloride. It is used in concentrations
ranging from 0.1-0.25% for preventive soil drenching or incorporation,
seed dressing, dipping of bulbs and roots and foliar application.
When used as a foliage-applied fungicide on fruit and vegetables
the dosage rates are 1.1-2.2 kg a.i./ha. For soil drenching,
propamocarb is used at 3.2-11.6 g/sq m or 0.11-0.66 g/plant and for
soil incorporation at 18.1-28.9 g/cubic m. Used as a seed dressing the
dosage range is from 0.36 g/kg (soybeans) to 28.8 g/kg (sugar beets).
Residues in crops are very dependent on the treatment. Residues
after drenching, soil incorporation or seed treatment are generally
low, while residues from foliar application are considerably higher.
As an example, residues in lettuce, on which propamocarb is
widely used, after spray application ranged from 0.4 mg/kg to 13 mg/kg
(25 mg/kg in glass-houses) (3 weeks pre-harvest interval), while soil
drench applications resulted in residues up to 6.3 mg/kg and soil
incorporation gave residues of 3.2 mg/kg or lower.
The meeting noted that residues resulting from spray applications
are high and, taking the TADS into consideration, it was unable to
recommend a TMRL for lettuce until more information on GAP and the
potential intake of propamocarb was available.
Residues in spinach and leeks after spray applications were of
the order of 5 mg/kg, while residues in other vegetables, such as
cauliflower, cucumber and tomato, and also in strawberries after spray
applications or soil treatments were below 1 mg/kg with few
exceptions. As the trials on spinach and leeks were not in accordance
with approved uses, which were available to the meeting, no residue
limits could be estimated for these crops.
Metabolism studies have been carried out for propamocarb on
lettuce and tobacco, in soil and in water, but as propamocarb has not
been approved for use on crops used as animal feedingstuffs no feeding
studies have been carried out.
Laboratory as well as field experiments on the metabolism of
propamocarb in soil have shown that propamocarb is metabolized under
aerobic conditions with an estimated half-life of the order of 2-3
weeks, but the breakdown only commences after lag phases from 5 days
to 8 weeks depending on the micro-biological activity of the soil.
Intermediate metabolites were observed only in low quantities
indicating that their decomposition was at least as fast as that of
the parent compound. Identification of the intermediates was not
feasible.
In laboratory tests the dissipation of propamocarb in soil under
anaerobic conditions was very slow, with an estimated half-life of
more than one year.
Leaching studies have been made on different soil types. Leaching
was observed to some extent in soil types containing up to 20% of clay
and silt (0.2 mm). After 30 days ageing most of the applied
propamocarb was mineralized in all soils except in one type in one
experiment, in which a soil with a higher content of clay and silt was
used. Only 20% of the propamocarb was mineralized, and a considerable
proportion of it appeared in the leachate. The leaching behaviour of
propamocarb seems therefore to be influenced by other factors besides
particle size and organic matter content.
The metabolism of propamocarb was investigated after spraying the
14C-labelled compound on lettuce. Less than 10% remained as
non-extractable material 36 days after treatment and 60-85% or more
consisted of unchanged parent compound. Up to 17% of the extractable
fraction consisted of degradation products, which were later shown to
be mainly formed at the extractions stage during the analysis.
Tobacco plants treated by soil drenching took up propamocarb via
the root system. The distribution in the plant was such that the
concentration gradient from bottom to top was of the order of 100:1,
i.e. residue levels in the oldest leaves were 50-200 times higher than
in the youngest leaves and flowers.
Bluegill and channel catfish were exposed to propamocarb either
by adding 14C-labelled compound to the water or by intraperitonal
injection. Propamocarb was taken up from the water into the tissues,
but in all experiments the compound disappeared when the fish were
transferred to untreated water. Water from the experiments in which
14C-labelled propamocarb was injected into the fish, contained
propamocarb, metabolites which were not identified, and one compound
which co-chromatographed with 3-dimethylaminopropylamine by TLC.
Propamocarb is very stable to hydrolysis in acid as well as basic
aqueous solutions. Irridiation at wavelengths above 290 nm had no
effect on the degradation of propamocarb dissolved in water. When a
mineral salt solution was added together with acetate, as a carbon
source, and a few drops of lake water, propamocarb was degraded very
rapidly after a lag phase of two weeks.
Residues of propamocarb in plants, soil and water can be
determined by gas chromatography using a thermionic detector operating
in the nitrogen-specific mode. The compound is extracted with 0.1 N
HC1, and cleaned up by partitioning between aqueous and organic
phases. The compound is determined as propamocarb base. The limit of
determination is 0.05-0.1 mg/kg, depending on the material analysed.
As only very small amounts of metabolites have been observed in
plants, soil and water, the method has been developed for
determination of the parent compound only.
RECOMMENDATIONS
The following levels are recommended as temporary MRLs which need
not to be exceeded when propamocarb is used according to good
agricultural practice. The limits refer to the parent compound only,
determined and expressed as propamocarb base.
Commodity TMRL Pre-harvest intervals on which
recommendations are based
Beets 0.2 drenching or seed dressing
Cauliflower 0.2 12-40 days
Cucumber 2 drenching or drip irrigation
Tomato 1 drenching
Peppers 0.2 drenching
Strawberries 0.1 drenching or spraying after planting
FURTHER WORK OR INFORMATION
Desirable
Information on good agricultural practices, including pre-harvest
intervals, in the use of propamocarb on fruit and vegetables.
REFERENCES
The Schering reports mentioned in the list are all unpublished.
Brühl, R. Mobility of Propamocarb Hydrochloride in Four
June 1978a Soils. Schering Report PA 66 752.71/6.
Brühl, R. Uptake of 14C-SN 66 752 by Tobacco Plants.
September 1978b Schering Report PA 66 752.62/6.
Brühl, R. Rationel Plant Uptake Study with Radioactive
January 1979a Propamocarb. Report of Progress I.
Schering Report PF-E/R+S 1/79 - PA 66 752.72/6.
Brühl, R. Degradation of Propamocarb Hydrochloride in a
May 1979b Californian Loamy Sand. Schering Report R+S 29/79
- PA 66 752.71/6.
Brühl, R. Degradation of SN 66 752 in a Loamy Sand under
June 1979c Anaerobic Conditions. Schering Report R+S 31/79 -
PA 66 572.71/6.
Brühl, R. Adsorption-Desorption of Propamocarb Hydrochloride
November 1979d in Soil and Sediment. Schering Report R+S 63/79 -
PA 66 752.71/6.
Brühl, R. Terminal Residues of Propamocarb Hydrochloride in
February 1980 Lettuce. Report of Progress I. Schering Report R+S
10/80 - PA 66 752.81/6.
Brühl, R. Determination of Target Compounds for Residue
May 1981a Analysis in Propamocarb Hydrochloride Treated
Lettuce. Schering Report R+S 25/81 - PA 66
752.81/6.
Brühl, R. Formation of Artificial Breakdown Products During
October 1981b the Extraction Process of Propamocarb
Hydrochloride from Lettuce Tissue. Schering Report
R+S 38/81 - PA 66 752.81/6.
Brühl, R. and Celorio, J. Degradation of SN 66 752 in a Loamy
October 1978 Sand. Schering Report PA 66 752.71/6.
Brühl, R. and Celorio, J. Mobility of SN 66 752 in Two Standard
December 1979a Soils. Schering Report R+S 68/79 - PA 66 752.71/6.
Brühl, R. and Celorio, J. Mobility of SN 66 752 in Two Soils After
May 1979b Ageing. Schering Report R+S 28/79 - PA 66
752.71/6.
Brühl, R. and Celorio, J. Degradation of Propamocarb Hydrochloride
November 1980a in German Standard Soils 2.2 and 2.3 at 15°C.
Schering Report R+S 58/80 - PA 66 752.71/6.
Brühl, R. and Celorio, J. Degradation of Propamocarb Hydrochloride
December 1980b in a Loamy Sand. Schering Report R+S 71/80 - PA 66
752.71/6.
Brühl, R. and Celorio, J. Anaerobic Degradation of Propamocarb
November 1980 Hydrochloride in River Sediment.
Schering Report R+S 60/80 - PA 66 752.71/6.
Fournier, J.-C., Massenot, D. and Drogoul, C. Effect of Various
1981 Pesticides on the Degradation of 2,4-D,
Isoproturon and Propamocarb. Importance of some
Experimental Conditions. Proc. EWRS Symp. Theory
and Practice of the Use of Soil Applied
Herbicides, 103-110.
Gray, C. and Knowles, C.O. Uptake of Propamocarb Fungicide by
1980 Bluegills and Channel Catfish. Chemosphere, 9,
329-333.
Gray, C. and Knowles, C.O. Metabolic Fate and Tissue Residues of
1981 Propamocarb in Bluegills and Channel Catfish.
Chemosphere, 10, (5), 469-478.
Hughes, L.B. The Effects of Propamocarb Hydrochloride on
July 1981 Symbiotic Dinitrogen Fixation, Sulfur Oxidation in
Soil, Carbon Turnover in Soils and Nitrogen
Turnover in Soil. Univ. Missouri-Columbia and
Schering Report.
Iwan, J. Metabolism of Propamocarb Hydrochloride by Soil
July 1979 Microorganisms. Report of Progress No. 1.
Schering Report R+S 38/79 - PA 66 752.73/2.
Iwan, J. Metabolism of Propamocarb Hydrochloride by Soil
September 1980 Microorganisms. Behaviour in Sterilized and Non-
Sterilized German Standard Soil 2.2 Report of
Progress No. 2. Schering Report R+S 48/60 - PA 66
752.73/2.
Iwan, J. Microbial Degradation of Propamocarb Hydrochloride
February 1983 in Water. Schering Report R+S 13/83 - PA 66
752.73/2.
Jenny, N.A. Determination of SN 66752 Residues in Green and
April 1979 Cured Tobacco (Shortened Method). Schering Report
66 752/NA 15.
Jenny, N.A. Dissipation of Propamocarb in United States Soils.
January 1980a Schering Report 66 752/NA 46.
Jenny, N.A. Dissipation of Propamocarb in United States Soils.
February 1980b Schering Report 66 752/NA 47.
Klehr, M. Photolysis of Propamocarb. HC1 (SN 66 752) in
February 1978 Aqueous Solution. Schering Report APC 06/78.
Klehr, M. Photolysis Experiments with Propamocarb. HC1 (SN
June 1980 66 752) in Heat Sterilized Aqueous Solution.
Schering Report.
König, B. and Ottnad, M. Residue Determination of SN 66 752 in Water.
July 1977a Schering Report 66 752/1 - PA 752.51/5.
König, B. and Ottnad, M. Specific Determination of Residues of SN
October 1977b 66752 in Lettuce and Soil (66 752/2). Schering
Report PA 66 752.51/5.
Meallier, P., Pouyet, B., Calvet, R., Fournier, J.C., Soulas, G.,
1983 Gauvrit, C., Calmon, J.P., Mitjavila, S., Tissut,
M., Narbonne, J.F., Coste, C., Viallet, P. and
Varagnat, J. Pesticides et Environnement.
Groupement d'Intérét Scientifique (GIS),
Université Claude-Bernard Lyon I.
Noack, S. Determination of Residues of SN 66 752 in Green
October 1978 and Cured Tobacco (66 752/3). Schering Report PA
66 752.51/8.
Ottnad, M. Dissipation of SN 66 752 from a Treated Soil in
June 1977a Frohnau (Field Study). First Report. Schering
Report PA 66 752.71/5.
Ottnad, M. Dissipation of SN 66 752 from a Treated Soil in
July 1977b Frohnau (Field Study). Second Report. Schering
Report PA 66 752.71/5.
Ottnad, M. Dissipation of Propamocarb Hydrochloride (SN 66
December 1977c 752) from two German Standard Soils. First Report.
Schering Report PA 66 752.71/5.
Ottnad, M. Leaching of Propamocarb Hydrochloride in three
January 1978a German Standard Soils. Schering Report PA 66
752.71/5.
Ottnad, M. Dissipation of Propamocarb Hydrochloride (SN 66
January 1978b 752) from two German Standard Soils. Second
Report. Schering Report PA 66 752.71/5.
Repenthin, W. Determination of Rates of Hydrolysis of
June 1976 Propamocarb Base (SN 39 744) at pH 5, 7 and 9 at
25°C. Schering Report APC 26/76.
Scheuermann, H.J. Analytical Method for the Determination of
November 1983 Residues of Propamocarb-Hydrochloride (SN 66 752)
by Gas Chromatography in Crops, Soil and Water (66
752/4). Schering Report R+S 45/83 - PA 66
752.51/11.
See Also:
Toxicological Abbreviations
Propamocarb (Pesticide residues in food: 1984 evaluations)
Propamocarb (Pesticide residues in food: 1986 evaluations Part II Toxicology)
Propamocarb (JMPR Evaluations 2005 Part II Toxicological)