164 Agricultural Gazette. 



they are so slight that I think it maybe questionable whether they would 

 account for any but the very slowest spread of the disease. Even when the 

 worms pas3 from plant to plant in the same paHdock it is questionable 

 whether the movement is not due to transportation by some of the numerous 

 agencies constantly at work in their neighbourhood. Almost everything 

 that moves either in or upon the soil may transport the minute eggs and 

 larvfc of gaii-vvorms. Air, water, animals are all agents in disseminating the 

 disease. The manner in which winds may act has already been alludod to, 

 and some precautions, such as mulching, suggested. Under the head of 

 drainage wo have seen how necessary it is in combating root-gall to have an 

 eye to the surface currents which during rains may pick the disease up as it 

 were, and dc])osit it in mass elsewhere. The action of subterranean water 

 has also been lightly touched upon. The general lay of the land determines 

 largely the nature and direction of the currents in the soil. These doubtless 

 have something to do with the spread of the disease. Here very little can 

 be suggested beyond a proper system of drainage. 



One set oF agencies in the spread of root-gall, and a most important one 

 too, has not yet received consideration. I refer to other animals. Insects, 

 earth-worms, birds, domestic animals, man him.self, are all factors in the life 

 history of the gall-worm. Let the farmer who is fresh from cultivating his 

 infested paddock show me his boot, and tlie chances are that I shall be 

 able to remove from it small clumps of earth containing larvae of the 

 gall-worm. The hoofs of his horses are in a similar condition. If the 

 ■weather is damp, it only needs a gun to demonstrate that even the feet of 

 the magpie that followed the plough repeat on a smaller scale the same con- 

 ditions. The insect that burrows in the ground and brings to the surface 

 subterranean material is active in aiding the gall-worm in finding new 

 pastures. The egg or larva leaves the mandibles of the insect only to be 

 seized up by the wind, or pressed with other matter into some crevice in 

 boot or hoof, and thus, it may be, travel miles before being again set down. 

 This is far from beiug a fancy sketch ; every slatcmcnt rests on the most 

 unimpeachable observation. Even the hands when soiled from field work 

 may carry enough material to start a thriving colony of gall-worms. It only 

 needs to be washed off, and thrown with the water around the roots of some 

 favourite plant (to help it along, poor thing!), to form the nucleus for a 

 new infested area. But enough has been said on this head to put those 

 interested on their guard. The thorough cleansing of boots and hoofs before 

 passing from infested to uuinfested land is too obvious a precaution to need 

 mentioning. There could be no more appropriate closing statement to this 

 section than that of the general principle that whatever moves and comes 

 into contact with the eggs and larvfc of gall-worms is likely to afford them 

 the means of finding new victims. 



EXPLANATION OF PLATE IV. 

 The parsnip aiid potato represented came from Pretty Gully ; the remaining figures 

 are after Neal. lu all the figures the galls are clearly represented in the form of 

 irregular and often dark-coloured swellings. 



1. Peach. (Reduced.) 



2. Okra. (Keduced.) 



3. Parsnip. (One-halt natural size. ) 



4. Fig. (One-fourth natural size. ) 



5. Potato. (Natural size. ) 



(i. Weeping-willow. (One-fourth natural size.) 



7. liadish. (One-fourth natural size.) 



8. Cow-pea. (Reduced.) 



9. Grape. (Reduced.) 



[One Plate.] 



Sydney : Charles Potter, Ooveminent Printer.— 1890. 



