1/6 MAINE AGRICULTURAL EXPPKRIMENT STATION. I909. 



"How to Fight Potato Enemies" which will be sent on appli- 

 cation to the Maine Experiment Station. , 



Properly prepared and applied bordeaux mixture is a remark- 

 ably adhesive compound. If it once becomes dry on the foliage, 

 which only requires a short time, it will be effective and resist 

 excessive washings of rain for some time. The writer has 

 preserved specimens of potato leaves taken at Eoxcroft October 

 5, 1907, which are well coated with bordeaux mixture yet none 

 had been applied to them for 38 days previously. At Orono 

 during this period 6.66 inches of rain fell; 2.18 inches of this 

 fell in 24 hours. These leaves had been thoroughly sprayed 

 6 times during the season. If bordeaux mixture does not show 

 these adhesive qualities there is some fault with the method of 

 preparation which should be remedied. 



IMPROPER SPRAYING. 



During a four-day trip over several of the larger potato grow- 

 ing towns in Northern Aroostook shortly after the blight had 

 become well established, just two fields were seen which had 

 been properly sprayed, yet some two or three thousand acres of 

 potatoes were inspected. These conclusions as to spraying 

 methods were arrived at by noting the condition of the fields, 

 inspecting the spraying machinery and questioning the owners 

 as to the methods of preparing the mixture, number of appli- 

 cations, time of application, etc. 



The sprayers as a rule are deficient in that they do not carry 

 enough nozzles and do not have sufficient adjustments. Bear- 

 ing in mind the nature of the fungus which causes the disease, 

 and the millions of spores which it produces, and bearing in 

 mind also that each and every one of these spores is capable of 

 infecting from one to several other leaves or tubers under right 

 conditions, it will be seen that under some circumstances a 

 sprayer which does not cover every leaf with a thin film of 

 spray may he practically useless unless this defect can be reme- 

 died. The results obtained from such sprayers being so unsat- 

 isfactory that spraying often becomes discredited with the user 

 and is abandoned. The majority of sprayers in use are 

 equipped with single nozzles to the row which cannot be raised 

 much above the tops of the plants, when the latter are full 

 grown. Such a sprayer used at the time when late blight is 



