CACTI 9 



In conservatories during the colder season, in order that the air 

 may be sufficiently dry, a temperature ranging from 60° to 70° F. 

 should be maintained. A temperature lower than 60° for any 

 considerable length of time would hold the moisture about the plants 

 too long and invite decay. During the warmer season, if the plants 

 are kept in the house, it is necessary that it be kept fully ventilated. 

 The aim is to have at all times a dry atmosphere and a moderately 

 moist, well-drained soil. If the plants are placed in open ground 

 during the summer months and their pots plunged in the beds, 

 these beds likewise must be thoroughly drained. In placing a 

 collection out of doors as a permanent planting, a situation should 

 be selected if possible where the ground slopes sufficiently to insure 

 perfect drainage. If natural drainage is impossible, a system of 

 draintiles should be placed throughout the area to be planted, and 

 the soil above the tiles should be made loose and porous by the 

 abundant addition of gravel and sand. Out-of-door planting is 

 preferably done during the dry season, so that the cut surfaces or 

 any injured portions of the plants may dry quickly, heal over, and 

 be less easily infected with rot. 



DISEASES 



The one disease from which cacti suffer more than any other is 

 rot. The plant body is so saturated with water that it forms an excel- 

 lent medium for the growth of rot-inducing organisms. This malady 

 is likely to attack the plant at any point. Any cut or bruised place 

 presents the most favorable point for infection, from which rot 

 spreads rapidly and destroys the plant. Water dripping on a plant 

 for even a short time may induce infection. By far the greater 

 number of plants receive the infection through their bases or roots, 

 whence it works upward through the center. By the time it has 

 reached the surface the plants are usually too far gone to be saved. 

 If the diseased condition is detected before it has reached the crowns 

 of the plants they may be saved by cutting away all the diseased por- 

 tions and then grafting the crowns on some healthy stock. Other- 

 wise it is best to remove the plants at once and burn them. The 

 soil in which they were potted and also the pots, if they are to be 

 used again, should be sterilized, so that other plants may not be in- 

 fected from them. 



Another disease, more common to species of Mammillaria and to a 

 less extent found on Echinocactus and Cereus, makes its first appear- 

 ance as a small light-orange colored spot on any portion of the plant 

 surface, usually starting at a pulvinus, which seems to be the point at 

 which the infecting germ enters. This spot steadily grows until the 

 plant is totally destroyed. The disease travels inward, toward the 

 center of the plant, following fibrovascular bundles. The colored 

 tissue readily separates from the healthier portion of the plant and 

 is easily removed, but this merely checks its ravages for a time. The 

 disease penetrates every portion of the plant and in time will make 

 itself manifest again in other orange-colored spots on the surface. 

 It is a contagious disease, and the only hope for saving a collection 



