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Show Answer by Prof. R. S. Northrop. The crown-gall and hairy root troubles which arc so often met with on nursery stock, arc not well understood. under-stood. A number of years ago, Prof. Tourney of the Arizona Experiment Station, conducted a long scries of experiments on this trouble and came to the conclusion that crown-gall was the result of one of the Myx-onyectes Myx-onyectes which arc some of the lowest forms of plant life. This, however, has been disputed by somes-recent somes-recent scientists although, while disputing, dis-puting, these men cannot find-hc specific organism which is responsible responsi-ble for this condition. Again some scientists claim that crown gait and hair root arc norboth caused by the same infc,cti5n, while others have madrinvestigations that lead' them to ,-fsupposc that the two conditions are different expressions of the same organism or-ganism working on the tree. I cannot positively say therefore,, what the exact cause is, but all people peo-ple who have thoroughly investigated this trouble, so far as I know, are agreed that infected plants should not be used: "As regards identifying the various conditions it is impossible impossi-ble to lay down absolute rules. Crown gall can be . identified by the galls which occur in the early stages and also by the long slender, slick roots which usually exist. Hairy root, is in mild" cases, undoubtedly the hard ( est to recognize but when the roots aonie off in little tufts and arc hair-likcand hair-likcand fairly well distributed, with the tendency for the main root to become be-come sickly and weak in appearance, the disease is evident and the stock should be rejected. I have, in times past, published two or three articles in the Dcscrct Farm- ji cr which deal with this question. M The lintiuircr, by 'referring to his files, can find the articles mentioned. If it is desired that other literature be secured' for a study of this mat- ( ter, I would suggest that the bulle- j tins which have been published by the department of agriculture, can be secured by writing to the depart- ment. I o |