T 0068/85 (Synergistic herbicides) 27-11-1986

1. The appeal complies with Articles 106 to 108 and Rule 64 EPC and is therefore admissible.

2. The present Claim 1 is substantively that on which the contested decision was based, the only difference being that the nearest prior art (1) is now duly taken into account in the pre- characterising portion and that the adjective "synergistic" has been replaced by the formulation "in a quantity producing a synergistic herbicidal effect", which is clearer. The latter amendment makes allowance for the fact that "a synergistic effect is produced only when the two active ingredients ... are combined in amounts which may vary within certain limits", (page 2 of the application as filed, penultimate paragraph, lines 1 to 4). There are accordingly no formal objections to the claim.

3. According to Claim 1 the application relates to an agent for selective weed control based on a mixture of 3-isopropyl-(1H)- benzo-2,1,3-thiadiazine-4-one-2,2-dioxide (II) and a compound of the 4-pyridyloxy-alpha-phenoxy propionic acid ester (i) type. Independent Claims 4 and 7 relate to a weed control process using the agent claimed in Claim 1, and to the use of the agent for that purpose.

4. Mixtures comprising herbicides of type (i) and various other herbicides including (II) which are complementary in terms of the weeds to be destroyed are already known from the nearest prior art (1).

5. The problem the invention sets out to solve, however, is to reduce the quantities of herbicide used, for economic and environmental reasons, while increasing the safety margin for cereal and soya bean crops (cf. also page 3 of the published application, first paragraph).

6. The solution proposed is to combine with (II) as a type (i) compound 4-(3',5'-dichloropyridyl-2'-oxy)-alpha-phenoxy propionic acid propargyl ester (Ia) or the corresponding thiopropionic acid propargyl ester (Ib) in an amount producing a synergistic herbicidal effect.

7. That (Ia) or (Ib) combined with (II) in certain proportions does have a synergistic effect when applied to certain types of weed, so that smaller quantities of herbicide are needed, is credibly demonstrated by Tables I to VI; see in particular, with regard to (Ia), in Tables I and II the effect of 0.5 kg/ha in combination with 0.5 kg/ha of (II) (ratio 1:1) when applied to Ipomoea purpurea and in Tables III and V the effect of 0.25 kg/ha in combination with 1 kg/ha of (II) (4:1) when applied to Chrysanthemum segetum (4:1) and, as regards (Ib), in Tables IV and VI the effect of 0.25 or 0.5 kg/ha in combination with 1 or 0.5 kg/ha of (II) (4:1 and 1:1 respectively) likewise when applied to Chrysanthemum segetum. The two aforementioned ratios are in fact the limits specified in Claim 3 and to that extent the Examining Division expressly acknowledged that the subject-matter met the requirements for patentability (see page 4, paragraph 2; page 9, paragraph 1; and page 10, paragraph 4 of the contested decision).

8.However, the Examining Division objected to Claim 1 in the version on which its decision was based, citing in each case Article 83 EPC, on the grounds that (i) a skilled person "could not prepare mixtures that were genuinely synergistic ... without knowing the range of ratios in which ingredients had to be mixed" (page 9, paragraph 2), and (ii) it had "not been demonstrated that the synergistic effect ... occurred throughout the claimed range" (page 10, paragraph 3). The Board construes the cited passages of the contested decision as meaning that the Examining Division disputes the claim that the proposed solution really does solve the problem in its entirety.

8.1 The Board sees no basis for such an objection in Article 83 EPC, which stipulates the disclosure required of a European patent application as a whole. The question of adequate disclosure may under no circumstances be adjudged solely on the basis of the claims (cf. Decision T 14/83, Vinylchloride resins/SUMITOMO", OJ EPO 3/1984, p. 105, Headnote I). The Examining Division does not maintain that the disclosure in the description lacks clarity and completeness - rightly since it, like Claim 3, states the precise ratios "generally" and "preferably" coming into consideration (page 3, last three lines) and in what quantities the active ingredient combinations are to be used (page 4, lines 1 to 4) etc. Further clear information is given in Examples 1 to 6.

8.2 The objection that should have been made is one under Article 84 in conjunction with Rule 29(1) and (3) EPC, namely that the claim is too broad. Claims must state "those technical features which are necessary for the definition of the claimed subject-matter" (Rule 29(1)(a)) and independent claims must state "the essential features of an invention" (Rule 29(3)) (cf. unpublished Decision T 115/83 dated 8 November 1983, point 4).

8.3 In the present case, however, it is clear from the reference in the original documents (page 2, penultimate paragraph) to the two active ingredients being combined in amounts which may vary "within certain limits" that the synergistic effect, which is the whole point of the invention, is not produced by combining (Ia) or (Ib) and (II) at random. Due allowance is, however, made for that qualification when the claim as it now stands states that the claimed agent - in addition to (II) - contains (Ia) or (Ib) "in an amount producing a synergistic herbicidal effect".

8.4 This form of words is a "technical feature" within the meaning of Rule 29(1) and (3) EPC.

8.4.1 A technical feature is one that can be read by a skilled person as an instruction as to the technical procedure to be followed to achieve a given result. Such an instruction may be explicit - for example in chemistry where "ethanol is the solvent" or "starting material substance having the formula X" - or functional, i.e. defined in terms of the result, as in expressions such as "fat- dissolving solvent" or "compound with a reactive hydrogen atom". Applied to the present case, the feature "weight ratio between 1:1 and 1:4" in Claim 3 is explicit, and the feature "... in a quantity ... effect" in Claim 1, functional. A functional feature is usually chosen out of the legitimate desire to couch the invention in the most general terms possible in order to secure adequate and reasonable protection. While in chemistry explicit features are often chosen in preference to functional ones, the latter occur far more frequently in other technical fields. Thus a claim relating to a mechanical invention would be unlikely to refer to a nail or a rivet, but to fastening means - a functional feature. Since patent law is indivisible there is no reason why functional features should not occupy their rightful place beside explicit features in chemistry too.

8.4.2 However, the applicant cannot simply define a feature in a claim as he wishes; he must choose the form that is objectively more precise (cf. Decision T 14/83 already cited, especially Headnote II, and T 4/80 "Polyether polyols/BAYER", OJ EPO 4/1982, p. 149). This requirement is met in the present case as the Board does not see how the limits within which the two herbicide couples combine to give a synergistic effect could be defined more precisely than has been done without limiting the scope of the invention. Accepting the Examining Division's suggestion and including in Claim 1 as it then stood the features expressed numerically in Claim 3 so as to render the former more precise would mean limiting the scope of the invention unjustifiably to a particular range of weight ratios and thus unacceptably restricting protection to only part of the invention as disclosed.

8.4.3 On the other hand, the effort to define a feature in functional terms must stop short where it jeopardises the clarity of a claim as required by Article 84 EPC. That clarity demands not only that a skilled person be able to understand the teaching of the claim but also that he be able to implement it. In other words, the feature must provide instructions which are sufficiently clear for the expert to reduce them to practice without undue burden, if necessary with reasonable experiments.

8.4.4 The clarity requirement is met in the present case: In interpreting the instruction in Claim 1 to combine compound (II) with compound (Ia) or (Ib) "in an amount producing a synergistic herbicidal effect", a skilled person will even on the basis of his general knowledge of the art, rule out combinations involving vastly different proportions. He will also be guided by the preferred weight ratios mentioned in Claims 2 and 3 in seeking other suitable ratios, which may vary considerably according to the crop to be protected or weed to be destroyed. Moreover, the skilled person is given precise directions - should he need them - as to how he can by means of various tests (Colby method) recognise and even calculate a synergistic effect when (Ia) or (Ib) have been used in "an amount producing a synergistic herbicidal effect", (cf. page 9, paragraph 3, to page 10, line 5, of the description and in Examples 1 and 1a). While the tests take a long time, since the plants first have to germinate and there is then a waiting period of 15 to 20 days for the results, all things considered, the effort called for on the part of a skilled person must be regarded as reasonable, since such tests are quite normal in the art and those used in the present case no more elaborate than usual.

8.5 The problem is therefore solved in its entirety by the invention claimed.

9. None of the citations discloses the full subject-matter of Claim 1. It is therefore new, as the Examining Division concedes (page 6 of the contested decision, lines 1 and 2).

10.The Board is therefore left with establishing on the basis of the nearest state of the art (1) whether the claimed invention involves an inventive step.

10.1 Type (i) compounds other than (Ia) and (Ib) are disclosed as herbicides in (1); also described are mixtures of these including many complementary herbicides (page 3, lines 1 and 2, and 6 which the effect of a mixture of (II) and a "compound No. 6" - a butyl ester of the 4-(5'-trifluormethylpyridyl-2'-oxy)-alpha-phenoxy propionic acid, hence a compound differing from (Ia) and (Ib) in at least two respects, is described).

10.2 Although compounds (Ia) and (Ib) are already known as herbicides from (3) (see for example Claims 8 and 9 on pages 42 to 43) it does not disclose active ingredients containing (Ia) or (Ib) in combination with other herbicides, and certainly not with (II) or producing a synergistic effect. There was nothing in (3) to suggest to a skilled person that he might solve the problem to which the application relates by combining (II) specifically with the herbicides disclosed in (3) and especially with (Ia) or (Ib). Of the 48 test results for mixtures of (II) with "compound No. 6" given in Table IV on page 28 of (1), six display some synergism but ten an antagonistic or counter-effect; there was hence no reason for anyone seeking synergistic herbicide mixtures such as those proposed to combine (II) with any compounds of type (i), and particularly not with (Ia) or (Ib).

10.3 Similarly from (2) - page 1045, paragraph 2 - it is already known that the effect of bentazone (II), identified as "V" therein, on dicotyledonous weeds can be intensified using growth regulators of the phenoxy propionic acid type. Compounds (Ia) and (Ib) are also, it is true, of this type but, as the appellants rightly point out in their submission received on 10 July 1986, there are considerable structural differences between them and the 2- (methyl-4-chloro phenoxy)-propionic acids which alone are specifically mentioned in this connection in (2). However, the main point, advanced by the appellants in that submission (page 2, eighth line from the bottom, to page 3, line 2) and one that is so far incontrovertible, is that (Ia) and (Ib) are not growth regulators. Consequently a skilled person could derive no suggestion from (2) that he might solve the problem by combining (II) with (Ia) or (Ib).

10.4 The subject-matter of Claim 1 accordingly involves an inventive step.

11.The subject-matter of independent Claims 4 and 7 is substantially the same and is based on the same inventive idea as Claim 1, so that it too is patentable.

12.Since dependent Claims 2 and 3 and 5 and 6 relate to advantageous embodiments of Claims 1 and 4 respectively, they, too, are allowable.