THE AGRICULTURAL XEWS. 



Februaky, 28 19U. 



FUNGUS NOTES. 



GREEN MUSCARDINE FUNGUS IN 

 SAMOA. 



The insect notes published on page 10 of the present 

 Volume of this Journal contained a reference to a fungus 

 discfivered in Samoa on the Iihinoceros beetle {Oryctes Rhi- 

 noro-os) which is a serious pest of coconuts in that island. 

 In the issue of Dcr Tropenjjflanzey for December 191.3 

 (Vol. XYII, p 660) Dr. Friederichs, Government Entomologist 

 of Samoa gives an account of the fungus and of its parasitism 

 on Oryctes. It turns out to be the now well-known fungus 

 Jtletarrhiziura anisoplioe. From the method of its occur- 

 rence, it is believed to be indigenous to Samoa, 

 although first discovered on the introduced beetle in 

 question. It was noticed that a number of the larvae in 

 captivity showed large, round, brown spots, and in about 

 a week the grubs were dead and covered with green 

 spoies. Healthy larvae brought into contact with them 

 tecame without exception infected and also died. The brown 

 spots mark the place of entry of the fungus. They are 

 not very sharply defined and are very variable in size; some- 

 times they are quite absent, a circumstance which may denote 

 infection with the food. The spots appear if spores are placed 

 on a slight wound produced by pricking the skin of the larva. 

 In most cases the diseased larvae become so full of the 

 mycelium of the fungus that they are converted into solid 

 bodies capable of being broken into pieces. At first the 

 mycelium is not e.xternally visible; later it forms a white 

 covering upon which the spores develop and soon enclose the 

 whole body in a blue-green layer. 



When pupae were placed in infected material the 

 beetles emerged but were immediately attacked. Adult 

 beetles could be infected by inoculation under the wing 

 covers, though most of them died from the direct eflfects of 

 the wound. A large number of beetles kept in a kerosene 

 till in earth and leaves to which a number of dead beetles 

 bearing the spores had been added all died and were found 

 covered with the fungus. Whether they had lieen killed by 

 it, or whether it had merely developed on their dead bodies, 

 as experiments showed to be possible, is uncertain. The 

 production of spores on the adults is considerably hindered 

 by the hardness of the outer covering. 



The fungus is so virulent that every larva which comes 

 in contact with the spores is infected and dies. The 

 laboratory in which these experiments were carried out 

 became so permeated with spores that it was found impossi- 

 ble by ordinary methods to rear the larvae at all. 



Experiments were carried out to determine the 

 possibility of infecting larvae in the open. Earth containing 

 infected material was mixed with a heap of rotted cacao 

 husks and 200 healthy larvae introduced. Seventeen days 

 later the heap was examined and all the larvae were found 

 dead and covered with the green spores. Later observations 

 showed that the beetles readily resorted to the heap to lay 

 their eggs and that the larvae on batching were immediately 

 killed. The heap retained its full virulence for several 

 months. Parallel experiments in another district have given 

 the same results and it has further been shown that the 

 beetles leaving such heaps after laying their eggs carry the 

 infection to adjacent breeding places. It is recommended 

 that only well rotted cacao husks be used in constructing the 

 heaps, otherwise the heat generated is too great, and further 

 it la recommended that the heaps be covered with a layer of 

 earth in order to prevent distribution of the spores of cacao 

 canker from the husks. 



SOIL STERILIZATION IN THE CONTROL 

 OP PLANT DISEASE. 



The subject of soil sterilization has received a great 

 deal of attention lately, and although the explanation of 

 some of the effects produced is still the subject of consider- 

 able doubt, the effects themselves are already proving 

 of great value in practice. As yet the methods available 

 are too expensive for use except on relatively small quanti- 

 ties of soil, and hence are most adapted to the purposes of 

 the gardener. 



Apart from any improvement in the fertility of the 

 soil, the elimination of parasitic organisms by one of these 

 methods may prove to be of great value to planters of those 

 tropical crops for which seed beds are used, whenever 

 trouble is being experienced with damping oti' or seedling 

 diseases, or where early infection with diseases of later life 

 is suspected. We give below, therefore, an extract from 

 a paper by L L Harter on Control of the Black Rot and 

 Stem Rot of the Sweet Potato published by the Bureau 

 of Plant Industry, U,S,D.A. (Circular 114), which gives 

 particulars of soil sterilization by two methods, involving 

 the use of steam and of formaldehyde solution respectively. 

 "Steam sterilization is preferable when possible. When 

 disinfecting hy steam, any system can be used that insures 

 the greatest efficiency with the least expenditure of time 

 and money. Efficiency, however, should be the first con- 

 sideration. It is a useless expenditure of time and money 

 to sterilize if it is not done thoroughly or, if after once 

 being thoroughly sterilized, the soil is allowed to become 

 infested by handling with shovels or by placing it in boxes, 

 etc , that have not been disinfected. 



'Some system patterned after the following plan is 

 suggested by W. W. Gilbert and, with such modifications as 

 are necessary to meet local conditions, may be found feasible. 

 A stationary or portable engine must be available which 

 can stand a pressure of 80 to 100 %. of steam. If 

 a stationary engine is used, the soil must be hauled to the 

 engine for sterilization. In such cases it will be found 

 convenient to construct a strong box which can be 

 tightly covered, sufficiently large to hold 1, H or 

 2 tons or more of soil, with li- to 2-inch perforated 

 iron pipes (the perforations to be about three-sixteenths of 

 an inch in diameter and 6 inches apart on the under side) 

 laid in the bottom about 1 foot apart, which can be attached 

 to the engine by a pipe or steam hose. This is easy to 

 accomplish by connecting the parallel rows of pipes in the 

 box with a header having an outlet connecting with the 

 engine. This box should be loaded on a wagon and hauled 

 to the farm and filled; then brought to the engine and ster- 

 ilized and again returned. If there is any general demand 

 for soil sterilization, several completely equipped boxes will 

 be needed. The use of portable boxes is advisable merely to 

 protect against reinfestation of the soil after it is sterilized. 

 'It will be more convenient to have a stationary steril- 

 izing box and haul the soil to and from it in a wagon, if the 

 necessary care is taken to wash out the wagon box with 

 a formaldehyde solution before the sterilized soil is again put 

 in it. This method will save time, labour and expense. The 

 soil can then be brought to the engine, scooped into the box, 

 spread out 8 or 10 inches deep over the pipes, sterilized, and 

 returned to the wagon. Practically the same methods can be 

 employed if a portable engine is used to sterilize the soil on. 

 the farm. 



'When the pressure is up to about the capacity of the 

 engine, probably 80 to 100 Bb., the steam should be 

 turned on by opening the valve about half way. Tlie higher 

 the pressure the drier the steam. The soil should be steril- 



