VEGETABLE AND FIELD CROPS 207 



erous hyphse may be seen with a good lens upon the spot 

 centers. 



These spots may destroy the greater part of the green 

 tissue of the leaf and its value to the plant as a sugar pro- 

 ducer, or even cause the leaves to die, in which event they 

 blacken and remain standing nearly upright upon the 

 crown. The death of the older leaves causes the crown 

 to elongate, suggesting the name " pineapple disease." 

 Dry weather followed by a damp spell most favors the 

 disease. 



Sprayed plants in New Jersey * gave a much cleaner 

 foUage and yielded 480 pounds of root as against 380 

 pounds from the unsprayed plants from an equal area, a 

 gain of nearly 26 per cent. The spray used was Bordeaux 

 mixture, 5-5-50, applied first when the plants were six 

 weeks old and subsequently at intervals of ten days for ten 

 sprayings. 



Root rot, rhizoctoniose (Rhizodonia fceteKiihn). — Beets 

 affected with this rot usually first show disease at the 

 bases of the outer leaves, which turn black. The stalks 

 weaken and allow the leaves to fall prostrate, though they 

 do not lose their color at once. The disease thence passes 

 into the crown, turning the attacked parts brown and later 

 leading to cracking of the root. In this condition the my- 

 celium of the fungus is clearly evident in the cracks. 

 Eventually the whole top may rot off. The disease spreads 

 rapidly from plant to plant in the field. Dry or cold 

 weather may so retard the disease that the plant can 

 recover if not too badly affected. 



The disease is probably the same that has been destruc- 



' Halsted, B. D., N.J. Agr. Exp. Sta. Bui. 107, p. 10, January 10, 1895. 



