Thielaviopsis is a much more serious trouble of pineapples than 

 of eane. It is the cause of practically all of the soft rot or shipping 

 rot as well as a base rot of slips, and spotting of the leaves. The 

 loss from the rot is exceedingly heavy, five to ten per cent of a ship- 

 ment being not uncommon, and cases are known which ran as high 

 as seventy-five per cent. The fungus has been also reported by Faw- 

 cett of the Mayagiiez Station as causing a ''stem-bleeding of 

 coconuts. 



Sufficient inoculations have been made to demonstrate that but 

 one form is involved in the attacks on the various hosts. 



A number of experiments have been carried out in seed treatment 

 (51). It was found that when the seed was planted under good con- 

 ditions no perceptible improvement in germination resulted between 

 treated and untreated lots. When disinfectants were applied to in- 

 fected seed or to good seed planted under poor conditions, there was 

 considerable improvement. As a consequence of these results, which 

 are in accord with those of other workers, treatment is recommended 

 only where the seed can not be planted at once, or where for some 

 reason conditions are not favorable. Bordeaux mixture is the only 

 practical material now in use for this purpose. 



Occurre.7ice in other countries. — This disease was reported by Gough 

 (36) in 1911 from Trinidad, and by Edgerton (21) from Louisiana 

 as rare. Of Hawaiian conditions Cobb (14) says "according to my 

 observations the pineapple fungus causes the decay of more cane cut- 

 tings in Hawaii than any other one cause. The expense of replanting 

 is largely due to the loss of cuttings through this rot." Butler (10) 

 states that in British India he had found it on three occasions only, 

 all being on recently imported seed from Java and Mauritius. It 

 is of considerable importance in Java where it has been studied by 

 Went (95, 96.) The disease also occurs throughout the British West 

 Indies, (18, 64, 70, 71), particularly in Barbados. 



Description. — The presence of the fungus can be readily noted by 

 the characteristic blackened sooty area running through the center 

 (PI. XIX, fig. 3,) of the stalk. There is also a very distinct odor of 

 pineapples present, hence the common name of the disease. There 

 has been much confusion in the literature between Thielaviopsis and 

 Melanconium, the macro and micronidia of the former having been 

 considered as further stages in the life cycle of the rind disease. 



Thielaviopsis paradoxa (De Seynes) J. Hohn. 



Sterile hyphae hyaline, or pale fuscous, septate. Fertile hypliae 

 septate, not branched. Macroconidia ovate, fuscous, catenulate, at 

 length separating ,thick walled, usually vacuolate, 16-19 X 10-12 



209 



