The patent proprietor filed an appeal against the decision of the Opposition Division to revoke its patent.
Claim 1 as granted read:
A fungicidal mixture, comprising(1) 2-[2-(1-chlorocyclopropyl)-3-(2-chlorophenyl)-2-hydroxypropyl]-2,4 dihydro-[1,2,4]-triazole-3-thione (prothioconazole) of the formula I or its salts or adducts
and(3) picoxystrobin of the formula Illor its salts or adductsin a synergistically effective amount.
The Board had to examine whether this subject-matter involved an inventive step.
*** Translation of the German original ***
[2.2] In view of document D1 the problem to be solved is to provide an alternative synergistically effective fungicidal mixture based on prothioconazole.
[3.1] The proposed solution consists in the composition of prothioconazole and picoxystrobin claimed in claim 1.
[3.2] Considering the results presented in Tables 3 and 4 of the opposed patent, the Board assumes that the above mentioned problem was indeed solved.
[3.3] However, the skilled person starting from document D1 and trying to solve the problem defined in point [2.2] did not have any good reason to mix prothioconazole with picoxystrobin as mentioned in document D1. It is true that document D2 discloses that picoxystrobin has some advantageous properties […] with respect to other strobilurins such as e.g. azoxystrobin and kresoxim-methyl known from document D1, but the document does not mention mixtures containing picoxystrobin and having a synergistic effect at all. Moreover, synergistic effects are unpredictable, i.e. when, as in document D1, a combination of two specific compounds has a synergistic effect, this does not mean that such synergy may also be expected when one of them is modified as to its structure. This can also be seen from the fact that document D1 discloses specific fungicides as constituents for the mixture (Mischungspartner) and not classes of fungicides.
Thus the combination of prothioconazole and picoxystrobin as a synergistic mixture is not obvious for the skilled person from the teaching of documents D1 and D2.
Documents D3 and D4, which have been disclosed in due time, concern a great number of fungicide mixtures containing picoxystrobin and one further active component, among which azoles […]. These mixtures are said to possibly possess a synergistic effect […]. However, these documents do not contain any further indications or examples in this respect. Moreover, prothioconazole is not among the listed active substances. Thus there is no indication for the skilled person that there could be a synergistic effect when prothioconazole and picoxystrobin are mixed.
[3.4] The [opponent] expressed the opinion that in view of the commercial success of several strobilurins […] and the improved properties of picoxystrobin with respect to the commercial strobilurins […] there was a clear indication for the skilled person to combine prothioconazole and picoxystrobin with reasonable chances of success.
This argument would be correct if the problem to be solved was merely to provide alternative fungicide mixtures. This is not the case here (see point [2.2]). The fact that picoxystrobin has properties that are improved over azoxystrobin and kresoxim-methyl […] does not allow to deduce that it also has a synergistic effect in a mixture with prothioconazole. Document D2 discloses experimental results relating to the activity of picoxystrobin in comparison with other known strobilurin derivates such as azoxystrobin and kresoxim-methyl, which are mentioned in document D1. Although the latter have a synergistic effect with prothioconazole […] this does not allow to draw the conclusion that picoxystrobin, despite its advantageous properties, will also have a synergistic effect when combined with prothioconazole.
[3.5] The [opponent] further argued that it was obvious for the skilled person to use compounds of the same class, i.e. strobilurins, and to obtain the claimed mixture by applying the principle of trial-and-error.
The Board does not fond this argument persuasive.
Fungicidal compounds belonging to the same class do, as a rule, possess similar modes of action (Wirkmechanismen) and/or possibly similar chemical structures. However, this does not mean that when certain fungicidal compounds of the same class have a synergistic effect when combined with a certain fungicidal compound, all or most compounds of this class also have a synergistic effect with this particular fungicidal compound. As a rule, synergy is not predictable […] and, therefore, cannot be ascribed to any mode of action and/or structure. In the present case, starting from document D1 and without any knowledge of the invention, the principle of trial-and-error invoked by the [opponent] would boil down to testing mixtures of different fungicidal compounds with prothioconazole, without it being predictable for the skilled person whether a mixture would indeed have a synergistic effect.
[3.6] The [opponent] has also stressed that according to the teaching of document D2 […] picoxystrobin was to be used in combination with other fungicides in different cross-resistant groups for controlling cereal diseases. This would be an incentive for the skilled person to combine picoxystrobin with other fungicides having a different mode of action.
However, the passage cited by the [opponent] refers to particular cross-resistant groups (i.e. combinations of strobilurins with Famoxadone and Fenamidone). Moreover, as stressed by the [patent proprietor] [this passage] refers to the resistance of certain pathogens to strobilurins in this context. At best the skilled person can understand this to mean that a combination of strobilurins with a fungicide could be advisable if they are to be used against these particular pathogens. The skilled person does not find in this paragraph an incentive to use picoxystrobin for solving the problem mentioned in point [2.2].
[3.7] Thus the subject-matter of claim 1 involves an inventive step. […]
The patent is maintained unamended.
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