DISEASES OF MINOR FRUIT PLANTS 345 



is thus greatly reduced, and in extreme cases the plant has 

 hardly any hold on the soil. 



The condition arises from the persistence of old leaf-bases 

 in a leathery condition at the time when new roots are being 

 produced from the internodes above. The new roots are unable 

 to penetrate the obstacle thus presented, and are deflected so 

 that their growth partly or wholly encircles the stem. Failure 

 of the first formed roots from asphyxiation or other causes, or 

 decay of the base of the rootstock, induce the condition by 

 forcing premature development from higher nodes. In planting 

 out suckers in dry soils it is advisable to remove beforehand the 

 lower leaf-sheaths so as to allow a free course to the roots ; in 

 wet situations decay of the old leaves is more rapid and the 

 operation may be dispensed with. 



The existence of the tangle-root condition is not necessarily 

 a symptom of disease, but it impairs the efficiency of the root- 

 system, reduces the rate and vigour of growth, and may in extreme 

 cases cause the failure of the plant under the strain of fruit 

 production. 



Root Disease, Wilt, or Blight. 



A condition of ill-health and failure known under one of 

 these names or an equivalent appears to be familiar in every 

 country in which any considerable cultivation of pineapples is 

 carried on. It has not been established as being due to any 

 particular parasite or any single cause, and it is not probable that 

 this is the case. Rather it is in its general aspect a form of failure 

 like the root disease of sugar-cane, and in its simplest form may 

 be brought about as the direct result of unfavourable conditions, 

 but in addition may develop characters tending more and more 

 towards those of parasitic disease according to the nature of the 

 organisms, usually fungi, which invade the weakened roots or 

 rootstocks. In this way variations in the final form of the 

 condition arise which differ in different situations and cause the 

 confusion of attempts to correlate them. One important question 

 on which evidence is definitely conflicting, probably for the reason 

 just given, is that of transmissibility. The disease as it exists in 

 Hawaii and Queensland has been reported to be seldom or never 

 communicated ; in Porto Rico, Jamaica and the Philippines it 

 has been regarded as infectious. 



Symptoms. 



In the form of the disease seen by the writer in Montserrat, 

 which is believed to be the one most common in these islands, 

 the plants showing external signs of the disease first occur in 

 patches and the affection appears to spread slowly through the 

 beds attacked, taking several months in the process. 



The general appearance is that of a slowly progressive wilting 



