154 



THE AGKICULTUKAL NEWS 



May 11, 1912. 



INSECT NOTES. 



BEL WORMS, OR NEMATODES. 

 PAET II. 



A circular of the Bureau of Plant Industr}-, United States 

 Department of Agriculture, issued on February 20, 191 2, entit- 

 led The Nematode Gallworm on Potatoes and Other Grops in 

 Nevada, deals with the serious occurrence of eel worms in 

 Nevada in 1910-11. The summary of this circular is given 

 herewith: — 



'During the seasons of 1910 and 1911 there has been 

 a serious infestation of certain potato fields in Nevada, caused 

 b}- a nematode gallworm known as Heterodera radicicola. 

 This has resulted in hindering th3 marketing of Nevada 

 potatoes in California, where the crop has been sold here- 

 tofore. 



'The parasite causing the disease is a very small unseg- 

 mented worm, which invades the roots of many different 

 plants, causing malformations, and often seriously hindering 

 the growth of thfe plants. The nematode multiplies very 

 rapidly under favpurabik conditions. The life-cycle may be 

 completed within a few weeks, and each female may lay as 

 many as 500 eggs. 



'The nematode may be carried from place to place in the 

 roots of living plants, in potatoes, on soil on the roots of 

 nursery stock, or with potted plants. It may also be carried 

 from one field to another in earth, on farm implements, or in 

 irrigation water. JIanure from yards where diseased roots 

 or tubers have been fed may carry the worm, and garbage 

 containing peelings of diseased potatoes is also a prolific source 

 of infestation. 



'The use as seed of any infected potatoes is to be strongly 

 condemned. No eBbrt should be spared to locate all infested 

 fields in a district where the nematode is known to occur, and 

 . seed potatoes should be secured from fields known to be unin- 

 fested, or, better still, from a region where, because of adverse 

 climatic conditions, the nematode is unknown. 



'A thorough inspection should be made of all fields in 

 each district where the nematode is suspected to occur, and 

 all infested fields should be devoted to crops which the 

 nematode does not attack. There are many plants besides 

 the potato which are susceptible to nematode injury, and 

 these should never be planted or allowed to grow in fields 

 where the gallworm is found. There are a number of crops 

 that are not attacked by this parasite, and these only should 

 be grown on infested fields until the nematode is practically 

 starved out. 



'It is very difficult to eradicate the nematode completely 

 when it is once well established in a field, but its numbers 

 may be so reduced by the use of immune crops that suscep- 

 tible crops may be grown again without serious injury.' 



In the summary given above, reference will be seen to 

 the effect which the outbreak of eel worms exercised on the 

 Californian market for Nevada potatoes. The presence of 

 this pest in certain counties in Nevada was considered such 

 a serious matter that a quaiantine order was i.ssued prohibit- 

 ing the importation of all potatoes from those counties. 



The following copy of the Order establishing the quaran- 

 tine prohibition on such potatoes is taken from the Monthly 

 BidletAn of the California State Commission of Horticulture, 



Vol. I, No. 1, December 1911, where it was published in an 

 article by Mr. E. O. Essig, Secretary of the Commission: — 



'Whereas, potatoes from Lyon, Churchill and Washoe 

 counties in the State of Nevada shipped into California, 

 have been discovered to be infested with eel worm, a destruc- 

 tive nematode worm; and Whereas, the planting and throwing 

 of such potatoes or parts thereof on the earth would likely 

 infest the soil with this serious pest; and 



'Whereas, Once in the soil, its riddance is almost impos- 

 sible, therefore, a horticultural quarantine be and 



'/s hereby declared and established, against all potatoes 

 shipped from the counties of Lyon, Churchill, and Wa.shoe, 

 State of Nevada, into the State of California, and all horticul- 

 tural commissioners and local inspectors are instructed to 

 destroy or return infected potatoes from the counties afore- 

 said to the place of shipment, at the option of the shipper or 

 his agent, and to take all proper precautions against the 

 introduction of the eel worm into the State of California.' 



An indication of the increasing recognition of the impor- 

 tance attaching to the presence of eel worms and the occurrence 

 of root knot may be seen from the attention that has been 

 given to the subject and the stringent quarantine regulations 

 that have been issued. A further indication is te be found 

 in an article by E. D. Anstead, B.A., Planting Expert to the 

 LTnited Planters' Association of Southern India, entitled 

 Eelworms Attacking Tea Seedlings, which appeared in the 

 Planters' Chronicle for February 17, 1912. In this article 

 an account by Dr. C. A. Barber, Government Botanist, 

 Madras, of the Nematode Heterodera radicicola, contains 

 information similar to that which has appeared in other parts 

 of the world recently, and also describes the attacks of the 

 pest on tea seedlings. 



Most of the crops which are described as being attacked 

 by eel worms, in the various publications mentioned, are not 

 those with which West Indian planters have to deal, but it 

 would be well to keep constantly in mind the fact that crops 

 in the West Indies are liable to attack and that climatic con- 

 ditions favour the development of the nematode worms. 

 Whenever any plants in the field, garden or nursery are seen to 

 be suffering from disease, the cause of which is not apparent, 

 it would be well for planters to suspect the presence of eel 

 worms and make a careful search for them. They may not 

 be now, or in the future, the cause of really serious injury 

 to staple crops' in the West Indies, but the knowledge of the 

 possibility which exists that this may happen should serve to 

 pl.tce West Indian planters on their guard. 



The Pernicious or San Jose Scale.— According 



to the Agricultural Journal of the Union of S',iith Africa, 

 Vol. II, p. 821, the Pernicious or San .Jose scale {Asjndiotus 

 perniciosus) has made its appearance in Natal. This insect has 

 proved a most destructive pest in North America, and has been 

 the cau.se of enormous loss to various fruitgrowing industries. 

 It has necessitated extensive experiments with spraying 

 material, and the records of the work done in connexion with 

 the control of this pest forms an enormous bulk of experi- 

 ment station literatm'e. As a result of the experience thus 

 gained and placed upon record, invasions of other countries 

 by this pest have not occasioned an equal amount of loss, 

 and it is encouraging to note that in the United States, 

 where the most severe attacks occurred, their virulence 

 has become less, partly on account of the greater degree 

 of control exercised by natural enemies, and partly because 

 of the better Bu'derstanding of the nature of the pest and the 

 method of control, on the part of agriculturists. 



