Minnesota Plant Diseases. 



213 



tention than a careless one and must prove of much greater 

 benefit. The matter of apparatus, as pumps, nozzles, etc., must 

 also be left to the judgment and to the financial possibilities of 

 the operator. Good apparatus is, however, indispensable. 

 Whether or not this shall be expensive depends on his ingenui- 

 ty and knowledge. 



Effect of fungicides. The object of the application of fungi- 

 cides is the destruction of the fungus pest. The substances 

 are necessarily of a poisonous nature and the fear is often en- 

 tertained by growers of plants that such applications may be in- 

 jurious to the host plant or to the consumers of the crops or to 

 domestic animals to which the crops or foliage may be fed. It 

 has been found that the fungicides listed below, if sprayed on 

 plants even with considerable frequency, can be made very 

 effective and yet never injure in the least the plant foliage. 

 It has even been claimed that copper solutions such as bor- 

 deaux are beneficial, but such an action is doubtful, or, at best,, 

 but very slight. The arsenic mixtures, such as Paris green r 

 which are used to combat insects, likewise exercise no injurious 



effects upon the host plant when 

 sprayed on in proper amounts. 

 Copper salts in strong solutions 

 are able to injure the roots of 

 plants very seriously but it has 

 been shown that by ordinary 

 spraying absolutely no danger 

 arises from this source, since but 

 a very minute quantity of the 

 salts penetrate to the roots. 

 Sprays sometimes fall from trees 

 onto grass beneath but experi- 

 ments have proven that the 

 quantity is not sufficient to be 

 injurious to cattle, horses or 

 sheep. This was demonstrated 

 for arsenical insecticides. Still 

 another question arises, viz., the 

 effect of sprays on such crops as 



FIG. 104.-A barrel pump. (The Deming orc h ar( J crops where the fruits 



