This invention belongs to the field of agricultural chemistry, and provides to the art a new method of controlling foliar phytopathogens which cause foliar plant diseases. 
A number of publications have disclosed plant-protective compounds which constitute the background of the invention. 
For example, British Pat.  No.  845,916 discloses that a family of N,N-dialkylanilines, which can bear three nitro groups, are useful as plant fungicides. 
Roberts, Ind. Eng.  Chem.  34, 497-498 (1942), and Goldsworthy et al.,  J. Ag.  Research 64, 667-678 (1942) discussed phytopathological testing of diphenylamine compounds including 2,4-diaminodiphenylamine and 4-nitrodiphenylamine. 
Belgian Pat.  No.  780,549 discloses halo-substituted diphenylamines which can bear nitro groups.  However, the Belgian patent describes compounds containing at least four halogen atoms, and the phenyl rings of the compounds are alternatively substituted with a variety of groups such as carboxy, sulfonamido, perhalocarbyl, hydrocarbylamino and so forth. 
German Offenlegungsschrift No.  2,363,602, published June 27, 1974, describes a group of diphenylamines having diverse substituents, some of which are the same as the substituents of the compounds of this invention.