222 MINNESOTA STATE HORTICULTURAL SOCIETY. 



rot. I do not think the rows treated the previous year with Bordeaux 

 mixture have made as strong a growth or produced as much fruit as 

 those not treated, but presume I was too liberal with the application of 

 the mixture. In some instances I notice that vines most severely cut 

 back by the frost did not thoroughly ripen the season's growth, and such 

 may be more susceptible to disease next season in case we should have a 

 superabundance of moisture. 



TREATMENT OF FUNGUS DISEASES OF THE GRAPE VINE. 



BY A. W. LATHAM, EXCELSIOR, MINN. 



This article is to be a brief record of my experience with this class of 

 grape diseases. It is necessarily brief, because the fortunate climate of 

 our state, so dry and clear, gives comparatively little encouragement to 

 the growth of fungi. Its depredations are mostly confined to the Dela- 

 ware grape. It is mainly the work of one species, the downy mildew, or 

 Peronospora. The powdery mildew, which botanists have given a heart- 

 rending name, with which I will not torture you, is the source of a little 

 annoyance upon the fruit of some varieties of the Rogers, notably, Nos. 4 

 and 15, and appears under favorable circumstances upon the unopened blos- 

 soms of the Cottage, Pocklington and occasionally other sorts. It is easily 

 destroyed by an application of flour of sulphur dusted on the attacked parts 

 as soon as detected. If looked for closely and treated at its first appear- 

 ance no serious harm will follow. Possibly a second application may be 

 needed later. With the downy mildew it is quite another thing. When 

 it appears upon the leaves of the vines, the mischief is already done and it 

 is too late to apply a successful remedy for that year. This disease must be 

 fought before hand, the vineyard must be fortified against it, and it must 

 not be allowed to get even a foothold. Without waiting to see whether 

 the weather of that particular season is to be favorable or unfavorable to 

 the growth of this parasite, the grower must act on the principle that it 

 will appear at its regular time, and do his work accordingly. The vine- 

 growers of this country are certainly under great obligation to the depart- 

 ment of agriculture for the intelligent, persistent and successful inves- 

 tigations it is conducting into the cause and cure of grape diseases, 

 especially grape rot and downy mildew. Experiments being made in many 

 parts of the country, furnish ground for belief that a successful rem- 

 edy for these diseases has been found. The treatment consists of liquid 

 applications of compounds, after several formulas, the active principle in 

 all of which is sulphate of copper, and the applications are to be made as 

 a preventative, beginning before the buds push in the spring and being 

 repeated at intervals of about two weeks till the fruit is nearly full size. 

 The more faithful the treatment the better the result. 



The formula which appears at this stage of the investigation to meet 

 with most favor is called the ammoniacal copper carbonate. It is 

 composed of copper carbonate, 3 oz.; strong ammonia, 1 qt.; water, 22 qts. 



My own experiments have been upon a limited scale and confined to a 

 block of 250 Delaware vines in the vineyard attached to my residence in 

 Excelsior. These vines have been in bearing some twelve years, and with 

 the exception of a few years while young have always suffered more or 

 less from the downy mildew. In two or three seasons the attack has been 



