H 



THE AGRICULTURAL NEWS. 



Janiauy 4, 1913. 



FUNGUS NOTES. 



A NEW GROUP OF FUNGI OK SCALE 

 INSECTS, 



Id the Annals nf JSofnny, \o\. XXV, No. XCIX, p. 842, 

 there appears an interesting note by Fetch entitled Note on 

 the Biology of the Genus Sei)iobasidium. Tlie writer poini.s 

 out that in this genus are included a fairly well defined 

 group of Basidioniycetous fungi formerly classified under the 

 genera Thelephora, Corticium and others related to these. 

 The members of the group occur mainly in tropical countries 

 and are found as a rule encrusting the living branches and 

 leaves of plants up to a height of 10 feet or more from the 

 ground' The variously-coloured sheets of fungus often cover 

 these parts for a distance of several feet, but they never kill 

 them or cause any noticeable injury. The question therefore 

 that naturally arises is upon what do these fungi live, since 

 they do not appear to be parasitic on the plants on which 

 they grow. 



From an examination of along series of specimens, Fetch 

 concludes that they are parasitic on scale insects, not, as in 

 the case of the well-known local forms, on individuals, but 

 upon whole colonies. This fact is of considerable interest 

 from a local point of view, because at least two species of 

 the genus Scptobasidium occur fairlj' commonly in these 

 islands. The first is one described under the name Thelo- 

 ])hor(i pi'dicell'ifa, in the Affi-iriiltiiral Nefs, Vol, IX, p. 286. 

 It is very common on lime trees in St. Lucia and forms violet- 

 grey, waxy patches on their branches; the patches are often of 

 considerable extent. In the description referred to it is 

 stated that the presence of the fungus is often associated 

 with the death of the parts affected; but it is also true that 

 very frequently, as recent examinations have shown, the 

 fungus may be present in large quantities without causing 

 any apparent injury. The association of this fungus with 

 scale insects that looked healthy is also recorded in the same 

 place, but almost certainly the presence under the older parts 

 of the fungus of numerous dead insects was overlooked. It 

 appears, therefore, that this fungus which is so universal in 

 the island mentioned is not harmful but useful; and that when 

 the parts of the trees upon which it is growing die, their 

 death is due to some other cau.se, very possibly the harmful 

 effect of the scale in.sects brought about before the fungus 

 has had time to overcome them. Another .species, almost 

 certainly belonging to the same genus and having probably 

 the same parasitic habit on scale insects, forms dark-brown 

 sheets also on lime trees and covers colonies of scale insects in 

 the same way as that (irst mentioned. It has been found in 

 Antigua and Dominica, but bus not yet been identified. It 

 seems quite possible that one or two other species of the 

 same kind may exist in the West Indies. 



A MEANS TO PREVENT CROSS-POLLIN- 

 ATION IN COTTON EXPERIMENTS. 



This is describe(i in the Annual Report of the 

 Ainerican Breeders' Assuciotion, Vols. YII and VIII, 

 lately received. It was devised after the trial of several 

 methods, including the use of the paper bag, in work 

 to obtain strains of cotton resistant to wilt disease 

 (Fusarium). It may be said that somewhat similar 

 methods using lengths of worsted in place of the 

 cojipL-r wire have been employed by the Imperial 



Department of Agriculture, and that it has been 

 suggested by this Department to use small rubber 

 bands in the same way. 



The method finally adopted consists in winding the 

 flower bud loosely with very fine flexible copper wire. The 

 operation is performed when the Hower has attained nearly 

 full size but before it has begun to open at the tip. The 

 wire used was No. 26 soft copper, which comes in 260-foot 

 rolls costing about 20c. It can readily be cut into desired 

 lengths of 6 to 8 inches with a pair of small scissors. The 

 flower bud is held very carefully in the left hand, the bracts 

 of the involucre being turned back with the thumb and 

 finger, while one end of the wire is very lightly hooked 

 through the corroUa at the thickened portion near the base 

 just enough to hold it, extreme care being taken not to go 

 too deep and thus injure the interior flower parts. The end 

 of the wire thus inserted is allowed to protrude about 

 iinch and is then turned over with the finger. This part 

 of tlie operation must be done very carefully to avoid tearing 

 the delicate corolla. With the finger still on the end of the 

 wire the remainder is loosely wound spirally around the 

 flower from base to tip, the spirals at the base being ]■ to 

 j|-inch apart and gradually becoming closer and smaller 

 toward the tip until the spiral is closed just above the top 

 of the bud. 



As the cotton flower increases in length very rapidly 

 during the last twenty-four hours before it ojjens, the buds 

 are not in the best condition to work with until five or six 

 o'clock of the evening before the day on which they are to 

 open. The work must therefore be done after o p ni., and 

 before 8 a.m. of the following day, since by this time on the 

 morning of a sunny day in July or August the tips of the 

 flowers begin to open sufliciently to allow small insects to 

 enter. Bees have been seen forcing flowers open before this 

 time in the morning, and entering to obtain honey. 



There is sufticient elasticity to the coiled pliable copper 

 wire to permit the normal development of the flower parts, 

 but in no case has a wired flower been seen to open to allow 

 an insect to enter. In fact, the slight growth that takes 

 place after the flowers are wired forces the tip of the corolla 

 into the end of the closed spiral and effectively seals it to 

 the entrance of even the smallest insects. 



After one gets the knack of the operation it can be 

 done very rapidly and with little or no injury to the flowers. 

 First the field is gone over and the hest plants are selected 

 and tagged conspicuously with white or bright-coloured 

 cloths so that they may be readily seen, and then from day 

 to day the flowers are wired and tagged as they reach the 

 right stage of development. 



The conditions under which the work was done render 

 the results in percentage of blooms finally harvested not at 

 all comparable with results secured i Uewhere where no 

 disease factor is present. In the first [ilac.-, it is not possible 

 as early as July or the fore part of August, the time when 

 inbreeding must be done, to determine which plants will 

 later succumb td the wilt disease, since many plants, appar- 

 ently in full vigour in late July, are entirely dead by 

 September. Furthermore, neither the size of boll nor the 

 length of lint can be determined at this time, as no bolls are 

 matured. It is therefore necessary to select a large number 

 of what then appear to be the most vigorous, productive 

 wilt resistant and otherwise desirable plants and make a very 

 much larger number of inbreeds that are eventually desired. 

 Hence the necessity for a rapid njethod 



In 111 10, 1,;577 blo.ssoms on 170 plants were inbred by 

 the copper wire method. After taking into account the con- 

 siderable number of selected plants that were later killed or 



