JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



CONTRIBUTIONS FROM THE WISLEY LABORATORY. 



XXXII. — Experiments on the Control of Narcissus Eelworm 



in the Field. 



By J. K. Ramsbottom, N.D.H. 



Experiments were conducted throughout the Autumn of 1917 to 

 determine the possibility of bringing land which had carried crops of 

 diseased bulbs to a state of profitable production. One acre of highly 

 infected land in the Spalding district was kindly placed at our disposal 

 for these experiments. This land had been planted with Narcissus 

 bulbs in 1915, and in the Spring of 1917 the eelworm disease was so 

 prevalent that it was considered unprofitable to expend labour on 

 lifting them in the approaching Autumn of that year. The grower 

 simply hoed off the foliage of the bulbs that remained in April and 

 drilled the ground with onions in the hope that he would get some 

 profitable return from the ground. It is interesting to note that, 

 although the onions germinated freely, the young plants wholly dis- 

 appeared owing to eelworm attack. It was decided that this piece 

 of ground afforded an excellent opportunity for carrying on field 

 experiments. 



Nature of the Experiments. — The experiments are classified into 

 three series. The first series was concerned with the application of 

 manures, the second with the chemical sterilization of the soil, and the 

 third with cropping small areas of the ground with crops which have 

 been recorded as host plants of Tylenchus devastatrix. 



Plan of Experiments. — Before marking out the beds the ground 

 was ploughed, harrowed, and rolled. The ground was then marked 

 out into one large rectangular bed 211 ft. by 161 ft. (area 3774 

 sq. yds.). This rectangular plot was then sub-divided into two 

 halves, 191 ft. by 73 ft., with a 5 ft. path intervening. 



The beds devoted to the applications of manures (Series I.) were 

 20 ft. by 20 ft. (area 400 sq. ft.), and are represented on the plan by 

 the letters A to J and duplicated A 1 to J 1 . These beds were separated 

 by two-foot paths taken out to a depth of four inches. 



The beds set down for the chemical sterilization of the soil (Series 

 II.) were 12 ft. by 6 ft. (36 sq. ft.), and are represented on the plan by 

 the letters K to T and duplicated K 1 to T 1 . A pathway of 3 feet 

 separated the beds. Surrounding these beds at a distance of 6 ft. a 

 12 ft. break of rye was sown in the Autumn in order to isolate the en- 

 closed beds from windswept soil, and so reduce the possibility ot 

 infected soil being blown on to the plots after treatment. 



