FUNGI AND DISEASES OF CANE CUTTINGS. 



THE PINEAPPLE FUNGUS {TMelaviopsis paradoxa.) 



The injury caused by this fungus is restricted to the cane cuttings. 

 An affected cutting is usually killed either before any shoots are pro- 

 duced or before the new shoots can establish themselves on their 

 own roots. The loss due to this disease varies considerably, depending 

 upon the variety of cane, moisture condition of the soil, and possibly 

 other factors. As will be noted in more detail later not all seed 

 which fail to germinate have been invaded by this fungus, but it is 

 responsible for the death of a large proportion. Out of one lot of 

 ■dead seed examined, twenty-five per cent showed this disease and 

 of another lot but ten per cent. The loss in some instances, however, 

 must be much higher. Of healthy seed growing under normal con- 

 ditions a negligible per cent will be attacked. The disease makes 

 great headway whenever conditions for prompt germination are lack- 

 ing, and becomes especially severe if the seed has been left in piles 

 or sacks for some time after cutting. For this reason all seed that is 

 to be shipped or which it is not possible to plant at once should be 

 treated. 



It is difficult to obtain satisfactory data as to the resistance of 

 the various varieties of cane from field observations alone because 

 of the fact that other fungi are so often involved in the death of 

 seed pieces. To overcome this difficulty seed of a considerable number 

 of varieties was obtained and inoculated with TMelaviopsis. After 

 these cuttings had l)cen planted a definite time they were dug up 

 and careful measurements of the amount of infection were taken. 

 The results are given in the following table and it will be noted that 

 there is a very decided varietal difference in susceptibility. 



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