156 Agricultural Gazette. 



no effoch in pliccking the disease. The longer the potato is left in the ground the worse it 

 gets. The disease seems to bo most aetivc in summer. You will scarcely see it in the lato 

 crop of potatoes. It affects mangels, parsnips, and potatoes worst. It does not seem to 

 trouble carrots or the roots of orange-trees. I have had to give up growing mangels the 

 past three years on account of the disease. The soil is naturally well drained, and a depth 

 of sub-soil sent up to 40 feet. Tlic insect or disease seems to live in the soil. 

 If any other information or samples are required, I will promptly attend to it. 



Your obedient servant, 



William Easson. 



I devoted tliree days to a further partial examination of the Pretty Q-ully 

 Scrub disease, and was confirmed in my first suspicion, namely, that the roots 

 were attacl<cd by a microscopic Nematode worm infesting the soil. The 

 results of my examination were outlined in conversation with the Director 

 of Agriculture, who at once saw the importance of carefully investigating 

 the disease. The e.tamination I had made was but very incomplete, and I 

 was cautious about making any broad statements concerning a disease so 

 superficially examined, and when, soon after, I was desired to make a written 

 report upon the disease, T consented to do so, with the understanding that 

 it should be re,i;arded as in every sense preliminary. Any opinions based on 

 Buch imperfect investigation as I have barely found time to make, must of 

 course be subject to revision when the life-history of the p)est has been 

 carefully followed through at least one entire year. I must add that much 

 of the investigation lies on the very verge of what can be accomplished 

 with the microscope of the present day, and furthermore, would be found 

 impossible by anyone not already familiar with the free-living Nematodes — 

 facts which will be constantly emphasized even in this preliminary report. 

 I have been made more willing to prepare this imperfect account by 

 representations setting forth that it was desirable to make kuowii to the 

 public the nature of the work coming ])ropcrly witiiin the scope of an 

 Agricultural Department, an argument whose weight is obvious. 



The Disease. 



I have not visited any Australian district infested by the disease under 

 discussion. For the manner and time of its appearance, the reader is 

 referred to Mr. Easson's letters.- As I shall soon point out, the disease is 

 caused by microscopic worms which pass certain stages of their existence in 

 the tissues of roots, there giving rise to the most obvious symptoms. When 

 the disease first appears, small galls of various shapes begin to form on the 

 roots at the points of attack. These galls when occurring on a rootlet have 

 been appropriately compared to luiots tied in a stout thread. AVhcn they 

 occur on the roots, they take on the form of more or less irregular excrescences 

 of various sizes up to a diameter of half an inch. If the plant is young 

 when first attacked, its leaves gradually become yellow, it droops and soon 

 dies. The time occupied by these changes varies with the nature of the plant. 

 Mangels and turnips die in a few weeks. Young trees on the other hand 

 withstand the disease for from (mo to two years, their vitality steadily 

 decreasing until at last their leaves drop and they sliow no further signs of 

 life. Upon examination the roots are found to be covered with galls. The 

 characteristic appearances produced by the disease are sufficiently illustrated 

 by (he plate at the end of this report. The plate represents, among other 

 thin!.'8, a parsnip forwarded from Pretty Gully Scrub by Mr. Easson. The 

 up])er rootlets are coiiipletely covered with small galls, and larger galls are 

 to be seen on the tap-root near its end, as well as on the large lower root 

 on the right. Here and there appear large excrescences or warts, also due 

 to the attacks of the worm. The plate also rc])resent8 a potato sent from 



