Vegetable and Field Crops 263 



many leaves as to give the plant the appearance of blight, 

 and resulting in complete ruin of the crop. The presence 

 of the leaf-spot distinguishes this from any of the blights. 

 Spraying with Bordeaux mixture is effective against this 

 disease though valueless against the various wilts. Especial 

 attention should be given to guard, by spraying, the seedlings 

 in the seed bed, using a weak Bordeaux mixture. Moving 

 among the plants when they are wet spreads infection. All 

 refuse should be burned or plowed under. 



Downy-mildew, late-blight ^'^ {Phijtophthora infestans 

 (Mont.) De Bary). — Arising from the same cause as the 

 dreaded potato blight, of which host the tomato is close kin, 

 is the tomato blight which causes large loss of the crop in 

 some sections of California. It has been reported also in 

 Massachusetts and Colorado. 



As with the potato, the amount of damage is closely 

 dependent upon weather conditions, the disease being greatly 

 favored by a warm, humid atmosphere. It appears suddenly 

 as dark, discolored spots on the fruit and other green parts. 

 On the fruit the spot, usually upon the upper side, is watery 

 and large. Many tomatoes, apparently healthy when 

 picked, rot in shipment, the rot being accompanied, under 

 humid conditions, by a fine, white surface mold. Dark spots 

 upon stems and branches soon extend throughout the whole 

 plant, giving it the appearance of one stricken by frost. 



Protective spraying with 5-5-50 Bordeaux mixture, as 

 recommended for the potato, will probably serve in case of 

 this disease. In regions of infrequent rainfall it is neces- 

 sary to spray only after each rain. 



Fruit-rot ^^'' {Phoma destrudiva Plow.). — Leaf-spots are 

 present, but it is as a spot upon either green or ripe fruit that 

 greatest injury is incurred. The spots are 1-3 cm. in diam- 

 eter, brownish-black, and depressed. This trouble is most 

 prevalent on tomatoes, originating in the South, and shipped 

 to northern markets, and on such fruits causes heavy losses. 



Blossom-end rot. — Readily recognized from its name, 

 this troublesome disease is essentially a dry, black rot ap- 



