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DISCUSSION ON ROOT KNOT. 



Prof. Hussmann: I think this is a very valuable essay, and wish to 

 say a few words in regard to it. The bluestone remedy is now used 

 in the East almost entirely for diseases of the grapevine, by spraying 

 several times after each rain. We all know that the grapevine is affected 

 by what we call the black knot. If this has proven so successful on 

 plum trees, why should it not be successful on grapevines? At least, it 

 is worth trying. I am led to the conclusion by a few experiments that 

 I have made, that the ripe rot in grapes that has troubled us so much 

 for the last few years can also be prevented by spraying with bluestone. 

 My friend, Herman Yeager, with whom I corresponded in regard to the 

 matter, and who was deputized by the Department of Agriculture to try 

 the bluestone remedies, has advised me that since he has applied them 

 frequently, sometimes as often as three or four times during the season 

 when they had frequent rains, he has succeeded in raising good crops 

 from vineyards where he never succeeded in saving any at all during 

 wet seasons from some varieties. These experiments date back as far 

 as six years, when he was first authorized by the Department of Agri- 

 culture to try the bluestone. And he says he has become so satisfied of 

 its practicability and of its being a preventive of all the rot which 

 they had on the Eastern grapevine, that he thinks it will prevent mildew 

 in any shape, and also the black rot. 



A Member: I would like to ask Mr. Smith if these trees were from the 

 same nursery, and also what stock they were on. 



Mr. Smith: The trees were from two different nurseries, and they are 

 on the plum stock. Invariably, in my experience, I have found trouble 

 with the plum stock. I know that my neighbors have root knots on 

 peach root. But in my own experience I have not found them on peach 

 root; only on the plum root. And when a year later I planted two 

 hundred, and fifty prune trees on plum root from another nursery, they 

 also were badly affected. They were planted on just the same kind of 

 land. I examined whole rows that were on peach root, and found no 

 knot on them. It is a strange fact, but it is true. 



Mr. Wilcox: This matter has been before the State Horticultural 

 Society many times. We have traced this disease where the Myrobalan 

 root has been planted on wet soil. The peach is used in Santa Clara 

 County on heavy, dry lands, and consequently has not become diseased 

 by the moisture. Some of the best prune trees I ever raised are on Myro- 

 balan stock, and I have planted during the last ten years more or less at 

 different times. But where they originated in heavy lands they became 

 diseased. Bluestone has been used forty or fifty years on wheat, so that 

 it would not smut or rust. If it is true that it has that effect on root 

 knot, does it not act mechanically on the sap that circulates through 

 the wood? And I would suggest that we experiment by introducing it 

 into the body of the tree. 



Mr. L. C. Frisbie, of Napa: I have experimented in chipping off the 

 knots, and I have found small worms in them. Whether they were the 

 produce of the knot, or whether they were the cause of it, 1 have not 

 been able to determine. I will also state that a number of trees which 

 I planted in deep sandy soil were slightly affected by root knot. I cut 

 off' the knots in planting the trees, and most of them recovered. I also 

 had Winter Nelis trees with root knots on them. And a year ago I 



