190 



THE AGRICULTURAL NEWS. 



June 6, 1914. 



FUNGUS NOTES. 



BASE ROT OF PINE-APPLES. 



During the recent visit to St. Kitts of the Commissioner 

 ■and the Mycologist of the Imperial Department of Agricul- 

 ture, an inspection was made of the manurial experiment 

 ■plots of pine-apples at La G'ldrite. The series compriEes 

 sepaiate plots treated with pen manure, tankage, sulphate of 

 Tpotash, and phosphate, a plot <\ith tankage, phosphate, and 

 potash combined, and a control plot receiving no manure. 

 The experiments were established in St. Kitts in (irder to see 

 ■whether fungus troubles expenenced in Antigua would be 

 met with in an island where pineapples have been very little 

 grown, and in a situation as to which there is no record of 

 the plant having been previously tried. The cuttings were 

 from the Ripley variety and were carefully disinfected with 

 r.ordeaus mixture before planting. 



The plots in question are just beginning to ripen their 

 fruit, and it is as yet too early to say whether the principal 

 disease, which causes an internal discoloration of the tissues 

 immediately beneath the 'eyes', will make its apjjearance. 

 A sickly, yellow appearance of many of the plants was, 

 however, very noticeable, and was made the subject of 

 investigation. 



It was found that the more seriously affected plants 

 were easily lifted by hand, and the number of living roots 

 was very small. The underground stems of these plants 

 were rotted to a degree broadly corresponding to the amount 

 of sickness visible in the leaves, the worst cases retaining 

 only a few roots attached imnjediately below the bases of the 

 lowest leaves. 



The investigation was pursued further in the laboratory. 

 Xo evidence of a disease attacking the remaining roots and 

 rootlets was found. The loss of the roots appeared to be 

 entirely due to the rotting of the stem from which they 

 Sfiring. he blackened tissues of the stem proved to be 

 filled with dark hyphae, penetrating the tissues in every 

 direction and lying in coils in the cells, and with a great 

 abundance of black spores produced in simple chains. 

 A large plant with healthy leaves and a well developed root 

 system was noticed, when carefully cleaned, to have a brown 

 spot about the middle of one side of the underground stem; 

 after being kept for four days in a closed chamber a rot of 

 the nature of that observed in the field had extended from 

 this point throughout the stem, and was found to be accom- 

 panied by the advance of the same fungus. 



The fungus appeared identical in character with 

 a macrospore-producing condition of Tldelaviupsis ]^aradoj:i.t, 

 X. Hohn {'1'. elhaceticus, Went.). No microspores were found 

 in course of formation, and none could be recognized with 

 certainty. If they were present at all it was in relatively very 

 small numbers. Of a number of the supposed macrospores 

 placed in hanging drops of 10 per cent, sugar solution a few 

 germinated and the resulting hyphae produced terminal chains 

 of similar spores from lateral branches. A piece of fresh 

 sound sugar-cane was washed in i per cent, formalin and cut 

 into four parts with a sterile knife. Each part was then 

 S[ilit; one half was inoculated with spores from the internal 

 1i-:-ues of a diseased pine apple plant, the other kept as 

 a control in the same Petri dish. In each case there was an 

 liiitnediate and abundant development of typical Thielaviop- 

 ^is, with microand macrospores, from the point of inocula- 

 li-'P, while in each case the control remained sterile. No 

 pile apple plants were' available for inoculation experiments, 

 but the ai^pearance presented by the fungus in question in 



the tissues afforded good presumptive evidence that it 

 causes the disease, and there seems no reason to doubt that 

 it is identical with Thielaviopsis parado.ra. 



The presumption is strengthened by a comparison with 

 the disease known as base rot of cuttings described by 

 L. D. Larsen in Bulletin 10 (Pathological and Physiological 

 series) of the Hawaiian Sugar Planters' P^xperiment Station. 

 The description and photographs given accord very closely 

 with the appearance of the St. Kitts specimens, and conclusive 

 proof was obtained in Hawaii by means of inoculation experi- 

 ments that Thieiaviopsis is the cause of the disease. It was also 

 demonstrated that the fungus is able to live in and penetrate 

 for some distance into ordinary soil. An increase of organic 

 matter was found to induce quicker growth and more 

 thorough penetration of the fungus through the soil. 

 Further, it vpas shown that pure strains from pine apple and 

 from sugar-cane were capable of infecting the alternate host 

 plant and were indistinguishable in their virulence and 

 behaviour. 



Thieiaviopsis is well known in countries growing sugar- 

 cane as a wound parasite of that plant and the cause of great 

 destruction of cuttings in certain seasons. It is a curious 

 coincidence that when it was described by Went in 1893 as it 

 occurs on sugar-cane in Java, he gave it the name of pine-apple 

 disease owing to the characteristic smell produced by its 

 action on the cane, while it has since been found to give rise 

 to the most serious diseases of the pine-apple itself. 



It is obvious that in cane-growing countries the fungus 

 will always have to be seriously reckoned with in pine apple 

 cultivation. Sterilization of the cuttings before planting can-- 

 not be counted on as a preventive measure against an organism 

 which is generally present in the soil, and which is extremely- 

 likely to be present in any organic manure applied. In the 

 La (xuerite plots there was no evidence that any of the 

 manurial treatments had helped the plants to resist the- 

 fungus. A number of the plants remained apparently healthy, 

 but one of the best looking of these was the plant mentioned 

 above as having the beginning of an attack upon it. 

 There is some evidence that plants sometimes throw off th& 

 disease, and the experiment is worth watching with a view 

 to securing a resistant strain. It would appear that it is only 

 in this direction that hope lies of avoiding losses which 

 would be pretty sure to be sometimes serious. 



A New Spray Fluid.— Dr. Max Issleib, writing 

 in Mailers Deutsc/ie Giirtner-Zeitung, suggests the use of the 

 jelly-like matter produced by boiling certain algae in water 

 for the purpose of a spray fluid. He points out that when 

 certain marine algae {Chondriis rrisjyus and Gigartina 

 maiiiillona) are heated with water, 2'-52 parts of the former 

 with 100 of the latter, a gelatine-like fluid is produced which, 

 sprayed on plants, sets to form a thin skin, in which insect 

 pests are entangled and destroyed. It may be mixed with 

 5 or 10 per cent, petroleum or paraffin. The substance 

 recommended is one which has many applications. We 

 ourselves have it in common use for the stiffening of jellies 

 and the like, and its properties are indeed remarkable. The 

 fisherfolk of lirittany collect the red seaweed, Chondrus 

 crinpus, expose it on the grass to dry and bleach, and send it 

 to Germany, where as we are told, it is used to give body for 

 jam. The consistency of the jelly which it makes is, of 

 course, determined by the amount of water which is added 

 to the dry seaweed. In our household about as much as 



