Phosphorous Acid
[
Synonyms
]:
Orthophosphorous acid; phosphonic acid
[
CAS No
]: 13598-36-2
[ Molecular Formula ]: H3PO3
[ Molecular Weight ]: 82
[ d ]: 1.6510
[ M.p. ]: 73.6°C
[ b.p. ]: 200°C (decomposing at 180°C)
[ Molecular Weight ]: 82
[Specifications ]:
| Content |
98%min |
| Phosphate |
0.2%max |
| Chloride |
0.02%max |
| Sulphate |
0.01%max |
| Heavy metal(as pb) |
0.001%max |
| Iron |
0.005%max |
| Water solubility
test |
excellent |
[ Usage ]:
Raw material of the manufacture for phosphite and plastic
stabilizers. Reducing agent in chemical reaction, and used
in synthetic fibre and agro-chemicals industry.
[ Packing ]: In 25kg plastic woven bag or
kraft bag.
[Safety Data Sheet ]:
Phosphorous acid is corrosive and causes burns. In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. Wear suitable protecting clothing.
UN classification number : 2834
IMDG code : 81502
[Relativity]:
Salicylic and Phosphorous acid – possible alternative to copper |
W. K. Kast
Staatliche Lehr- und Versuchsanstalt f Wein- und Obstbau
P. O. Box 13 09, D-74189 Weinsberg
e-mail: Kast@lvwo.bwl.de
Abstract:
Salicylic acid (S) and phosphorous acid (P) were tested in field experiments in order to minimize the use of copper in organic viticulture. Both substances reduced infestation with downy mildew mainly in the prebloom and bloom period. S (applied 0,2 %) had a small effect (maximum 50 % disease reduction). However, P (applied 0,1 %) showed a very good protective effect and could even be used for curative treatments. The amount of S-residues found on grapes and in wine was comparable to that found on other fruits with a naturally high content (< 1 mg/kg). Residues of P were found to be higher (˜ 30 mg/kg).
Keywords: salicylic acid, phosphorous acid, copper, downy mildew, vine, vitis vinifera
Introduction:
The use of copper as a fungicide in organic viticulture against downy mildew (Plasmopara viticola) causes serious environmental problems. Salicylic acid is a natural substance which is part of the defense mechanism of plants. Phosphorous acid is an anorganic substance, that occurs naturally in plants, however in an extremely low dose. Both substances are not listed in the annex II of the EEC-regulation 2092/91 but would fit the principles of the regulation. The objective of our investigations was to proof, whether these substances could help to replace or reduce the use of copper.
Material and Methods:
In 1998 the effect of salicylic acid (0,2 %) and phosphorous acid (different concentrations 0,025 – 0,2 %) and combinations with copper and Mykosin was tested in a field trial (location Burg Wildeck – organic research station) using 10 applications. In addition, the effect of salicylic acid (0,2 %, 10 applications) was compared with a conventional fungicide (Aktuan, 0,125 %, 6 applications). In this experiment severe artificial primary infections caused an extreme spread of downy mildew. In 1999 different combinations of phosphorous acid and salicylic acid with copper and Mykosin were tested, also at Burg Wildeck research station. In one plot phosphorous acid 0,1 % was applied as a curative fungicide (4 applications) using a disease predictor (Adcon-Advantage-PeroDiag). Grapes, must and wine were analysed for residues by RCC Ltd. Thingen/Switzerland and Rkstandsanalytik Bremen GmbH/Germany.
Results and discussion:
In all experiments disease pressure was high. 10 applications of salicylic acid significantly reduced the disease incidence in all experiments but the effect was small (0 – 60 % reduction). Phosphorous acid reduced disease incidence best in Juli (> 90 %). But afterwards disease rapidly attacked the leaves. The use of curative sprays with phosphorous acid was very successful in June and July. A synergistic effect was found for the combination of low doses of phosphorous acid (0,05 %) and salicylic acid but was not well tolerated by the grapes at higher temperatures. Residues of salicylic acid in wine were increased, however at a level comparable to different other fruits (table 3). Residues of phosphorous acid were found up to a level of 60 mg/kg-1 (table 4).
Table 1. Results of field experiments using Salicylic acid
|
treatment |
frequency on leaves % |
incidence on grapes |
|
July |
September |
July |
September |
untreated (1998 a)
Salicylic acid 0,2 % (10 x)
Aktuan SC 0,125 % (6 x)
LSD 5 % (Tukey-Test) |
58.6
27.1
4.1
4.8 |
93.5
62.6
7.1
6.2 |
39.3
14.9
0.4
6.0 |
27.9
16.4
0.6
4.4 |
untreated (1998 b)
(1) Salicylic acid 0,2 % (10 x)
(2) Kupfer fl. 450 FW 0,04 % (10 x)
(1) 0,1 % + (2) 0,04 % (10 x)
(1) 0,2 % + (2) 0,04 % (10 x)
(1) 0,2 % + Mykosin 0,8 % (10 x)
LSD 5 % (Tukey Test) |
63.7
61.4
59.3
55.4
52.2
51.2
7.9 |
42.3
25.3
27.0
23.2
16.2
23.4
8.0 |
94.4
85.8
70.4
68.6
68.8
69.0
6.7 |
52.5
54.0
45.8
41.4
37.4
33.3
8.4 |
untreated 1999
(1) Salicylic acid 0,2 %
(2) Kupfer fl. 0,04 % (10 x)
(3) Mykosin 0,8 % (10 x)
(1) 0,2 % + (3) 0,8 % (10 x)
(1) 0,2 % + (2) 0,02 % (10 x)
LSD 5 % Tukey Test |
32.8
23.3
6.2
10.7
4.8
10.3
7.7 |
99.2
99.2
23.2
36.7
36.3
61.2
11.3 |
2.7
1.1
0.9
0.3
0.1
0.3
1.1 |
15.3
8.3
3.1
2.1
2.5
4.7
5.7 |
Table 2. Results of field experiments using phosphorous acid
| treatment |
frequency on leaves % |
incidence on grapes |
| July |
September |
July |
September |
untreated (1998)
(1) Phosphorous acid 0,025 % (10 x)
(1) 0,05 % (10 x)
(1) 0,1 % (10 x)
(1) 0,2 % (10 x)
(1) 0,05 % + Salicylic acid 0,2 % (10 x)
Kupfer 450 FW 0,04 % (10 x)
LSD 5 % (Tukey Test) |
63.7
56.2
47.3
26.1
4.6
21.7
59.3
7.9 |
94.4
87.4
79.6
62.8
39.2
77.0
70.4
6.7 |
42.3
33.2
28.0
4.7
1.1
5.6
27.0
7.9 |
52.5
53.2
42.9
14.4
2.1
21.6
45.8
8.4 |
Untreated (1999)
(1)Phosphorous acid 0,1 % (10 x)
(2) Kupfer fl. 450 FW 0,04 % (10 x)
(1) 0,1 % + (2) 0,04 % (10 x)
(1) 0,1 % (4 x curative treatments)
LSD 5 % (Tukey Test) |
32.8
2.3
6.2
2.0
1.0
7.7 |
99.2
93.8
23.2
39.8
96.5
11.3 |
2.7
0.2
0.9
0.4
0.2
1.1 |
15.3
1.5
3.1
2.3
6.1
5.7 |
Table 3. Residues of Salicylic and phosphorous acid (mg-kg)
| sample |
Salicylic acid |
Phosphorous acid |
| untreated |
0,2 % |
untreated |
0,025 % |
0,05 % |
0,1 % |
0,2 % |
grapes 1 daa*
grapes 14 daa
grapes 28 daa
grapes 42 daa
grapes at harvest
must
wine |
0.1
0
0
0
0
1.2
0 |
3.0
0.8
0.5
0.5
0.3
1.2
0.9 |
0.2
0.4
0.3
0.4
0.5
1.2
1.2 |
1.5
1.4
6.9
6.8
7.1
4.7
13.9 |
1.3
18.5
14.1
13.6
12.7
10.0
14.0 |
3.9
39.2
26.6
26.6
14.1
27.1
31.1 |
6.3
89.7
63.9
60.2
30.7
46.3
57.9 |
* daa = day after last application |
