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found prune trees on peach roots in a nursery, that were nearly every 

 one covered with root knot. 



Mr. A. D. Pryal, of Alameda: Seven or eight years ago I had 

 occasion to visit one of our nurseries. The owner was taking up his 

 peach trees, and I found that a great many of them were affected by 

 the root knot. I looked around and I saw that there was a field right 

 adjacent to the nursery, and that there was an herb growing in the field 

 and the herb was full of knots. I took some of those knots and opened 

 them and put them under a microscope, and I found the very same, 

 identical knot that the roots of the peach trees had. That was what 

 caused this root knot in the trees. I examined the blackberry and 

 raspberry and currant roots and found the same disease. And I found 

 a small insect. You can't see it with the naked eye. I notice among 

 us Professor Woodworth of the State University. I think he will bear 

 me out in the statement that the root knot is caused by a worm. 



Prof. Woodworth: There are a great many things that are called root 

 knot. The one that is produced by the Heterodera radicola is a differ- 

 ent one from that most commonly called root knot. It never gets to a. 

 large size. The root knot most commonly known is due to some other 

 cause, which is not known. Again, these true root knots, when they 

 become old and dead, and rotten, are attacked by the larvae of a small 

 fly. I am very much interested in the use of bluestone. I have watched 

 a series of experiments. There is no question that its use in some form 

 is very beneficial. The use of the Bordeaux mixture, however, which 

 is a bluestone and lime mixed, is a severe application. But it can be 

 made perfectly safe as an application to the outside of the tree, and it 

 produces its good results from the same cause — that is, the bluestone 

 that is in it. I have seen trees that were killed by being treated in the 

 spring of the year with bluestone. But there would be no probability 

 that we could ever introduce enough bluestone into the circulation of 

 the tree to kill the knot unless we put it into the knot. If we put it 

 into the knot we may kill the knot and not spread it enough in the tree 

 to injure it, if we do it in the fall, as the paper of Mr. Smith spoke of. 

 I use the bluestone always in the form of the Bordeaux mixture, and 

 in that form I consider it safe. 



Mr. Sprague: Mr. A. J. Roberts, of Alameda, assured me that he had 

 discovered his finest prune trees with root knots on them, and that so 

 far he was unable to detect any injurious result, although the presump- 

 tion was against there being no injurious result. 



Mr. President, I have brought with me for examination by this body, 

 a sample of the weed known as the Russian thistle, which is making 

 its appearance in Los Angeles County. It was never seen there before 

 a year ago. It is a very noticeable weed in that dry country, inasmuch 

 as it is a very bright green at a time when most other vegetation is 

 dry. The dangerous character of the weed may be inferred when I tell 

 you that in a very brief time it has depopulated portions of Dakota by 

 its rapid spread. We are told by bulletins from official sources that 

 farmers have been absolutely obliged to abandon their farms. It is an 

 evil of the greatest possible magnitude. It was doubtless introduced 

 into Los Angeles County by cars in transit, perhaps standing for a day 

 or two on the track. Its spread is greatly increased by the fact that 

 when it is dry it forms a stiff, rolling weed, which is blown by the wind 

 and scatters its seeds broadcast until it finds a lodgment. It grows 



