•138 



THE AGKICULTURAL NEWS. 



May 1, 1909; 



INSECT NOTES. 



Eel Worms or Nematodes. 



At the present time a considerable interest is being 

 shown in the nodules that may frequently be observed 

 on the roots of plants. .JIuch work has been done in 

 conne.\ion with the assimilation of nitrogen by means 

 of certain bacterial organisms, which cause the develop- 

 ment of characteristic root nodides, in which these 

 •bacteria live. 



The bacteria iiiliabit the roots of the Leguniinosae— that 

 group of plants in which the fruit is a pod. Among the 

 leguminous [)lants are the peas, beans, acacias, Ciis.sias, and 

 many other similar plants. Hecently, however, a theory has 

 been advanced that plants of other groups may also be able to 

 assinulate free nitrf>gen by means of bacteria and root 

 nodules, and many plants other than legumes have been 

 exannned with the object of determining whether or not rfiot 

 nodules are iiresent. 



As a result of this interest, root swellings have been 

 found on many plants and several enquiries have been 

 received at the Head Office of this Department with regard 

 to them. It may safely be. stated that in the West Indies, 

 nitvof'en bacteria have up to the present been found only in 

 the characteristic root nodules of leguminous plants. 



Eel worms are the cause of many deformities and swell- 

 ings in the roots of a great variety of plants. These swellings 

 arc usually quite distinct from the leguminous root nodules. 



The eel worms beloijg, to that group of animals known 

 as nematode worms, many of which are harndess, living in 



l-'io. 18. IJoins OF ( '(ir.Ki s 



I'l.ANT, snoWINO SWKt.I,- 

 INCS CAIISKI) HV Em. 



wc)i:\rs. 



I'lc. 10. liooT OF CoWFKA 

 Willi N'lTTlOCKN ( i AlllKl! 



im: Niiimr.Fs. 



»Iam|) situations, often in decaying organic matter. .Vt least 

 one species, however, is j)arasitic in man, and is known as 

 the filarial worm {Filnrin hunrrofti) which produces the 

 disease that is known as filariasis, Harbados leg, or 

 tdejihantiasis. 



The species (llftin-iidi'ra radii-ohi) which attacks the 

 roots of plants is the one which is commonly known as the eel 

 worm or nematode worm. It is so small as to l>e almost 

 iiivisildc to the unaided eye, but the adult female can be 

 distinguished liy the use i>f a hand lens. It is known to 

 occur in the I'nitcd Stales; "Mexico, and most of the islands 

 of ihe West In<lies, and in fict is widelv distiilmted in manv 



parts f)f the world. It seems likely that when more is known, 

 about the prevateice of eel worms in these islands, it will 

 be found that th^y are responsible for greater injuries to 

 growing plants,, than is .suspected by planters at the 

 present time. 



In previous numbers of the A;iiir)dtural Xevs (see Vo|. 

 Ill, p. 28.'$, and Yol. IV, p. 123) mention has been made of 

 eel worms. This pest has been found at Antigua on ochros, at 

 St. Lucia on lett^ice, at St. Vincent on yams, and at Barbados 

 on coleus and other garden plants. In Mexico, eel worms 

 attack cofi'ee, and are also known to damage cotton, tobacco^ 

 and many other plants. 



The attack of eel worms on the tender tissues results 

 in the production of a gall or distortion of the root, due to- 

 the irritating etfect of the presence of the pest. These galls 

 are not merely swellings due to the development of e.\tra 

 cells. This develojtment occurs in many instances, but it 

 also happens in addition that the ducts which convey plant 

 food and moistur^ to the leaves are eaten into, and Ijecome 

 disorganized and unable to perform their normal function.s. 

 Plants that are b;tdly attacked wilt and die. 



As already liientioned, it is probable that a great deal 

 of damage to growing crops in the ^Vest Indies is caused by 

 eel worms, although this damage is at present ascribed to other 

 causes. Examination of the roots of [)lants which are plainly 

 seen to be sutferirig from some unknoNsn cause will serve to- 

 fi.x; the blame for file injury when conspicuous galls are found. 

 But sometimes the swellings are small, and not greatly dif- 

 ferent from the foot nodules of the leguminous plants, and 

 it has been suggested that in the roots of sugar-cane, maize, 

 and other gramineous plants, the nematodes might be present 

 without forming galls, but at the same time cause a consid 

 erable amount of injury. 



It will easily be seen that injuries to the roots of plants, 

 such as those resulting from attacks of eel worms, would 

 atford a ready entrance for fungoid and bacterial plant 

 diseases. It seem^Veiy probable that many diseases of plants 

 are greatly assisted in their attacks Ijy the injuries caused by 

 eel worms. 



This suggcstioh indicates a line of ob.servation which 

 planters would do well to bear in mind. The Imperial 

 Department of Agriculture would be glad to Vie informed of 

 any cases of serious injury caused by eel worms. In cases of 

 attack by these minute pests, material supposed to be infest- 

 ed may be sent for examination to the local officers of the- 

 Department or to the Head Office. 



Eel worms are likely to become more numerous in the 

 tropics than in tertVperate regions, where they have to luulergo 

 the effects of a cold winter. 



The remedial measures to be enq)loyed would be of two- 

 kinds : The use ofchemioals or insecticides, and the adoption 

 of suitable culturaT'methods. The use of insecticides presents 

 many difficulties and chances for failure. The eel worms and 

 their eggs are inside the plant tissues, and conseipicntly very 

 difficult to reach with poisons or chemicals. 



In !Mexic(>, where the coffee trees are seriously attacked 

 1)V eel worms, jjiisoline, benzene, sulphate of iron, carbon 

 bisuljdiidc, and calcium carbide have been used with good 

 eflect (.see A<nl<-iiltiir'il Xeu'n^ Vol. VI, p. 12.3). If eel 

 worms liecome ii' pest in field cultivations in the West 

 Indies, it will he 'necessary to carry out ex|)erinK'nts to ascer- 

 tain 'he best reu,^edial measures. The use of lime in heavy 

 applications, rotat^6n of crop.s, and the cultivation- as catch 

 crops — of plants that are esitccially attractive to the pest, 

 !>nd which should be destroyed as soon as they are thoroughly 

 infested by the worms, should be tried. \'a]iorite may 

 perhaps [irove of vidue in this coiir.e.xiou.' 



