248 Report of the Botanical Department of the 



POTATO TROUBLES IN NEW YORK IN 1911. 



Over the greater part of the State the growing season of 1911 

 was very dry. Consequently, late blight (Phytophthora infestans) 

 occurred very sparingly. It made its appearance in a few locali- 

 ties, but came too late to cause material injury to the foliage. 

 Neither was there much loss from rot although traces of it were 

 found in a considerable number of fields in central and western 

 New York. Early blight (AUernaria solani), also, was scarce. 

 As in 1910, the leading troubles of potato foliage were flea beetle 

 injury and tip burn. Tip burn, especially, was very prevalent. 



DIRECTIONS FOR SPRAYING. 



In general, commence spraying when the plants are six to eight 

 inches high^ and repeat the treatment at intervals of 10 to 14 

 days in order to keep the plants well covered with bordeaux 

 throughout the season. During epidemics of blight it may be 

 advisable to spray as often as once a week.^ Usually, six applica- 

 tions will be required. The bordeaux should contain four pounds 

 of copper sulphate to each fifty gallons in the first two sprayings 

 and six pounds to fifty gallons in subsequent sprayings.^ 



1 On Long Island an earlier spraying is sometimes necessary to protect the 

 young plants from Ilea beetles which attack them severely while they are 

 coming up. For the best success in the control of bugs it is necessary to 

 spray with bordeaux and poison just as soon as a majority of the first brood 

 are hatched. Usually, this occurs when the plants are six to eight inches 

 high. Spray applied three days or more before the bugs hatch will fail to 

 kill many of them, because, in the interval the plants make considerable new 

 growth upon which the bugs can feed with impunity and cause considerable 

 damage before it is time to make the next regular spraying. 



2 On the south shore of Long Island between Southampton and Amagansett 

 this is frequently necessary. 



3 It can not be definitely stated what formula is the best one to use. Much 

 depends upon the quantity used per acre and the manner of its application. 

 Weak bordeaux applied in the form of fine spray which covers the plants 

 thoroughly may give better results than stronger bordeaux carelessly applied 

 in the form of coarse spray. Both the cost of chemicals and the expense of 

 application must be taken into consideration. It is plain, however, that the 

 mixture should be strengthened as the season advances and the danger from 

 blight increases. None of the ready-made bordeaux mixtures on the market 

 are as good as the home-made bordeaux. Neither can the lime-sulphur solu- 

 tion be profitably substituted for bordeaux in spraying potatoes (See Bui. 

 347 of this Station). In the preparation of bordeaux the writers prefer to 

 use stone lime rather than any of the " prepared " limes. 



