CHAPTER XXIX 



DISEASES OF MINOR FRUIT PLANTS 



Pineapple. 



The pineapple belongs to an order (Bromeliaceae) the greater 

 part of which consists of epiphytes and lithophytes (tree and rock 

 inhabiting plants) and the pineapple itself, while belonging to one 

 of the soil-inhabiting genera, is closely related in its constitution 

 and its vegetative structure to those of epiphytic habit. This is 

 reflected in the fact, emphasized by all authorities on the cultiva- 

 tion of the plant, that it is most decidedly intolerant of any inter- 

 ference with free root-respiration, such as is brought about by 

 soils which are close-lying or tenacious of water. Thus in Antigua, 

 where pineapples are more regularly grown than in the other 

 islands of the Lesser Antilles, the industry has practically speaking 

 been confined to the section of the island which possesses soils of 

 volcanic origin with a minimum of clay. 



Given good aeration the consistency of the soil is of minor 

 importance ; it appears that the plant will grow well in any soil 

 rich in humus, but in light soil it is especially necessary 

 that the supply of plant food be well maintained. The plant 

 will grow for a time in well-rotted leaf mould, and is grown in 

 Florida in sand with the addition of chemical manures. It would 

 seem that some of the difficulties attributed to disease have arisen 

 through a mistaken belief in the ability of the plant to thrive 

 in any light soil, which has resulted in the use of land in a 

 dried out or exhausted condition. It is important to note in 

 this connection that the plant has a very limited root range. 



The plant is well protected against drought, but cannot be 

 expected to do more than survive in periods when the com- 

 paratively shallow layer penetrated by its roots is dry. This 

 points to the need, in dry districts, of close planting to shade the 

 ground, mulching of the surface with leaves, or the maintenance 

 of an efficient dust mulch. 



Tangle-Root. 



The condition known as tangle-root is a frequent accom- 

 paniment of the root diseases described below, as it also is of 

 some dry soil conditions. In the affected plants the main 

 roots, instead of growing directly out into the soil, wind round and 

 round the rootstock, often quite tightly. The range of the roots 

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