Fungicidal compositions

Abstract

An improved fungicidal composition is a mixture of (a) fungicide used to combat phytopathogenic fungi and (b) at least one phosphonate or phosphinate of formula R.sup.1 R.sup.2 P(O)OR.sup.3 where R.sup.1 is C.sub.6-20 alkyl, C.sub.6-20 alkoxy or optionally substituted phenyl, R.sup.2 is benzyl, C.sub.6-20 alkyl optionally interrupted by NH or O, di-C.sub.6-20 alkylamino or the group --CH.sub.2 CH.sub.2 --R.sup.1 P(O)OR.sup.3, and R.sup.3 C.sub.6-20 alkyl. Some of the compounds of formula (I) are novel.

Description

This application is a 371 of PCT/GB97/01738, filed Jun. 26, 1997.

FIELD OF THE INVENTION

This invention relates to new fungicidal compositions.

PRIOR ART

U.S. Pat. No. 2,927,014 discloses phosphonates and phosphinates having herbicidal activity. In WO 9418837 and WO 9304585, it is disclosed that certain phosphonates can enhance the activity of specified herbicides. We have now found that such compounds can also be used with advantage in association with certain fungicides used to combat phytopathogenic fungi.

DESCRIPTION

The invention provides a fungicidal composition which comprises a mixture of

(a) fluquinconazole or azoxystrobin, and

(b) at least one phosphonate or phosphinate of formula I ##STR1## where

R.sup.1 is C.sub.6-20 -alkyl, C.sub.6-20 -alkoxy or optionally substituted phenyl

R.sup.2 is benzyl, C.sub.6-20 -alkyl, optionally interrupted by NH or O, di-C.sub.6-20 -alkylamino or the group ##STR2## and

R.sup.3 is C.sub.6-20 -alkyl.

Phosphonates of formula I wherein R.sup.1 is C.sub.6 -C.sub.20 -alkoxy and R.sup.2 is C.sub.6 -C.sub.20 -alkyl are known. They are made for example according the disclosure in DE 1,963,014.

Phosphinates of formula I wherein R.sup.1 is C.sub.6 -C.sub.20 -alkyl and R.sup.2 is phenyl can be prepared by catalytically induced addition of olefins to phenyl monoalkylphosphonites which are preferably prepared as described in DE patent 196 041 95.

Ethane-1,2-diphosphonic acid tetraalkyl esters of formula I wherein R.sup.1 is C.sub.6 -C.sub.20 -alkoxy and R.sup.2 is the group ##STR3## can be made by addition of the appropriate phosphonates to a dialkyl vinylphosphonate in the presence of basic catalysts such as sodium methylate or sodium hydride.

Alkyl- or dialkylaminoalkylphosphonic acid dialkyl esters of the formula ##STR4## wherein R.sup.3 is as defined above and R.sup.5 is R.sup.3 or hydrogen and x is 0 or 1 can be prepared according to two different methods. Compounds wherein x is 0 are made according to the following equation ##STR5## Compounds wherein x is 1 and made according to the following equation: ##STR6##

The addition of the amine is made in the presence of basic catalysts such as sodium methylate of sodium hydride according to the process described by A. N. Pudovik et al., Doklady Akad. S.S.S.R. 80365(1951); (A 50, 4143(1956).

Azoxystrobin is the common name for the fungicide methyl (E)-2-{2-[6-(2-cyanophenoxy)pyrimidin-4-yloxy]phenyl}-3-methoxyacrylate and fluquinconazole is the common name for the fungicide 3-(2,4-dichlorophenyl)-2-(1H-1,2,4-triazol-1-yl)-4(3H)-quinazolinone).

We have found that phosphonates of formula I, which have little or no activity in their own right considerably enhance the fungicidal activity of fluquinconazole and azoxystrobin.

The weight ratio of component a) to b) is generally between 10:1 and 1:10, preferably between 3:1 and 1:5.

The compound of formula I can be added to conventional formulations of component a). It may be desirable to also add small quantities of solvent and/or surfactant especially a non-ionic surfactant, and other additives such as fatty acids to improve the emulsifiability of the compound of formula I.

The following Examples illustrate the invention. Examples 1 to 6 describe the preparation of what are believed to be novel phosphonates and phosphinates, which can be used in admixture with azoxystrobin or fluquinconazole.

EXAMPLE 1

Into a reaction vessel, which was heated to 100.degree. C., with a reflux condenser (-15.degree. C.), were simultaneously added aqueous formaldehyde (12.17 g of 37% solution) and a mixture of di(2-ethylhexyl)amine (36.22 g) and di(2-ethylhexyl) phosphonate (45.96 g). The mixture was heated for 1 hour with stirring and then cooled to 20.degree. C. The water was removed by distillation under reduced pressure to give di(2-ethylhexyl){[di(2-ethylhexyl)amino]methyl}phosphonate, as a colourless liquid (n.sub.D.sup.20 =1.4563).

EXAMPLE 2

A mixture of 2-ethylhexyl vinylphosphonate, 2-ethylhexylamine (66.50 g) and sodium hydride (0.10 g) was stirred at 130.degree. C. for 6 hours. After addition of an additional amount of sodium hydride (0.10 g) and stirring 9 hours there was obtained di(2-ethylhexyl){[2-ethylhexyl)amino]methyl}phosphonate, as a colourless liquid (n.sub.D.sup.20 =1.4537).

EXAMPLE 3

To a mixture of 2-ethylhexyl vinylphosphonate (49.9 g), di(2-ethylhexyl) phosphonate (45.9 g) and THF (80 ml) was added to 20.degree. C. with stirring, a solution of sodium methylate in methanol until the mixture reached pH 8-9. The mixture was stirred for 12 hours and water (100 ml) and ethyl acetate (200 ml) added. The organic phase was separated, dried with sodium sulfate, filtered and the solvent evaporated under reduced pressure to give tetra(2-ethylhexyl) ethane-1,2-diphosphonate as a colourless liquid, n.sub.D.sup.20 =1.4488.

EXAMPLE 4

A mixture of 2-ethylhexyl vinylphosphonate (49.90 g), octadecylamine (40.43 g) and sodium hydride 0.10 g was stirred at 140.degree. C. for 6 hours. Water (100 ml) and ethyl acetate (200 ml) were added. The organic phase was separated, dried with sodium sulfate, filtered and the solvent evaporated under reduced pressure to give di(2-ethylhexyl)[2-(octadecylamino)ethyl]phosphonate, as colourless liquid n.sub.D.sup.40 =1.4541.

EXAMPLE 5

A mixture of tetradec-1-ene (30.05 g) and benzoyl peroxide (0.3 g) was added dropwise with stirring to 2-ethylhexyl phenylphosphonate (38.95 g) at 160.degree. C. The resulting mixture was stirred for 6 hours to give 2-ethylhexyl phenyl tetradecylphosphinate, as a colourless liquid n.sub.D.sup.20 =1.4813.

EXAMPLE 6

In a similar manner to example 5, starting from octadec-1-ene, there was obtained 2-ethylhexyl phenyl octadecylphosphinate, as colourless liquid n.sub.D.sup.20 =1.4729.

EXAMPLE 7

Wheat plants were inoculated with Erysiphe graminis (powdery mildew). One day after inoculation, they were sprayed with fluquinconazole, obtained by diluting with water to the desired concentration, a suspension concentrate comprising 50% by weight active ingredient, at a rate of 50 g fluquinconazole/ha either alone or mixed with various inactive phosphonate or phosphinate esters added at a concentration of 0.1% v/v, together with an appropriate emulsifier.

One week after spraying, the wheat was assessed for control of disease. The results are as follows:

______________________________________Phosphonate/phosphinate added % control______________________________________dihexyl octylphosphonate 97.2 dioctyl octylphosphonate 100 di(2-ethylhexyl) hexylphosphonate 100 di(2-ethylhexyl) octylphosphonate 100 di(2-ethylhexyl) decylphosphonate 100 di(2-ethylhexyl) dodecylphosphonate 100 di(2-ethylhexyl) tetradecylphosphonate 100 2-ethylhexyl phenyl tetradecylphosphinate (Example 5) 100 tetra(2-ethylhexyl) ethane-1,2-diphosphonate (Example 3) 100 2-ethylhexyl phenyl octadecylphosphinate (Example 6) 100 di(2-ethylhexyl) {[di(2-ethylhexyl)amino]methyl}phosphonate 85.2 (Example 1) di(2-ethylhexyl) [2-(octadecylamino)ethyl]-phosphonate 93.5 (Example 4) nil 0______________________________________

EXAMPLE 8

In a similar manner, Example 7 was repeated with some of the phosphonates and with replacing fluquinconazole with azoxystrobin. The results are as follows

______________________________________ con- active Rate Rate trol ingredient (g/ha) Phosphonate (% v/v) (%)______________________________________azoxystrobin 62.5 -- -- 29 azoxystrobin 125 -- -- 30 azoxystrobin 250 -- -- 94 azoxystrobin 62.5 di(2-ethylhexyl) octylphosphonate 0.2 98 azoxystrobin 125 di(2-ethylhexyl) octylphosphonate 0.2 100 azoxystrobin 250 di(2-ethylhexyl) octylphosphonate 0.2 100 azoxystrobin 62.5 compound of Example 4 0.2 100 azoxystrobin 125 compound of Example 4 0.2 100 azoxystrobin 250 compound of Example 4 0.2 100______________________________________

EXAMPLE 9

Example 7 was repeated in test against Puccinia recondita using azoxystrobin

Results are as follows:

______________________________________ con- active Rate Rate trol ingredient (g/ha) Phosphonate (% v/v) (%)______________________________________azoxystrobin 1 -- -- 8 azoxystrobin 5 -- -- 9 azoxystrobin 20 -- -- 23 azoxystrobin 1 di(2-ethylhexyl) octylphosphonate 0.2 29 azoxystrobin 5 di(2-ethylhexyl) octylphosphonate 0.2 85 azoxystrobin 20 di(2-ethylhexyl) octylphosphonate 0.2 91 azoxystrobin 1 compound of Example 4 0.2 79 azoxystrobin 5 compound of Example 4 0.2 90 azoxystrobin 20 compound of Example 4 0.2 93______________________________________

EXAMPLE 10

The following are typical formulations incorporating fluquinconazole and the preferred phosphonate according to the invention.

a) an SC formulation was made from the following components

______________________________________Ingredient g/l______________________________________fluquinconazole 100 di(2-ethylhexyl) octylphosphonate 320 emulsifiers 190 buffer 10 structuring agent 30 vegetable oil to volume 327______________________________________

b) a suspoemulsion was made to the following composition.

______________________________________Ingredient g/l______________________________________fluquinconazole 54 prochloraz 174 dispersant 25 emulsifiers 180 buffer 10 crystal growth inhibitor 38 di(2-ethylhexyl) octylphosphonate 174 aromatic hydrocarbon solvent 192 propylene glycol 40 antifoam 2 biocide 2 structuring agent 7.5 water to volume 176______________________________________

Claims

1. A fungicidal composition which comprises a mixture of

(a) a fungicidally effective amount of fluquinconazole or azoxystrobin and

(b) an enhancing effective amount of at least one phosphonate or phosphinate of formula I ##STR7## where R.sup.1 is C.sub.6-20 -alkyl, C.sub.6-20 -alkoxy or optionally substituted phenyl

R.sup.2 is benzyl, C.sub.6-20 -alkyl, optionally interrupted by NH or O, di-C.sub.6-20 -alkylamino or the group ##STR8## and R.sup.3 is C.sub.6-20 -alkyl.

2. A fungicidal composition according to claim 1, wherein R.sup.1 is C.sub.6-20 alkyl, and R.sup.2 is C.sub.6-20 alkyl optionally interrupted by NH.

3. A fungicidal composition according to claim 2, containing one or two 2-ethylhexyl groups.

4. A fungicidal composition according to claim 3, wherein (b) is di(2-ethylhexyl)octyl phosphonate.

5. A fungicidal composition according to claim 4, wherein (a) is azoxystrobin.

6. A fungicidal composition according to claim 5, wherein the ratio of (a) to (b) is between 1:10 and 10:1 by weight.

7. A fungicidal composition according to claim 6, wherein the ratio of (a) to (b) is between 3:1 and 1:5.

8. A fungicidal composition according to claim 3, wherein (b) is di(2-ethylhexyl)[2-(octadecylamino)ethyl]phosphonate.

9. A fungicidal composition according to claim 3, wherein (a) is fluquinconazole.

10. A fungicidal composition according to claim 1, wherein (a) is fluquinconazole.

11. A fungicidal composition according to claim 1, wherein (a) is azoxystrobin.

12. A fungicidal composition according to claim 1, wherein the ratio of (a) to (b) is between 1:10 and 10:1 by weight.

13. A fungicidal composition according to claim 1, wherein the ratio of (a) to (b) is between 3:1 and 1:5 by weight.

14. A method of augmenting the activity of the fungicides fluquinconazole or azoxystrobin used to combat phytopathogenic fungi which comprises employing a fungicidally effective amount of said fungicides in combination with an enhancing effective amount of at least one phosphonate or phosphinate of the formula R.sup.1 R.sup.2 P(O)OR.sup.3 where R.sup.1 is C.sub.6-20 alkyl, C.sub.6-20 alkoxy or optionally substituted phenyl, R.sup.2 is benzyl, C.sub.6-20 alkyl, optionally interrupted by NH or O, di-C.sub.6-20 alkylamino or the group --CH.sub.2 CH.sub.2 --R.sup.1 P(O)OR.sup.3, and R.sup.3 is C.sub.6-20 alkyl.

15. The method of claim 14, wherein R.sup.1 is C.sub.6-20 alkyl, and R.sup.2 is C.sub.6-20 alkyl optionally interrupted by NH.

16. The method of claim 15, wherein the phosphonate or phosphinate contains one or two 2-ethylhexyl groups.

17. The method of claim 16, wherein the fungicide is azoxystrobin and is agumented by di(2-ethylhexyl)octyl phosphonate.

18. The method of claim 14, wherein the ratio of the fungicide to said at least one phosphonate or phosphinate is between 1:1 and 1:10 by weight.

19. The method of claim 14, wherein the ratio of the fungicide to said at least one phosphonate or phosphinate is between 3:1 and 1:5 by weight.