REMOVING ROOT KNOTS 



the disease infectious. If the knot has not increased in size suf- 

 ficiently to seriously interfere with the growth of the tree it can 

 be smoothly removed, the wound treated with the Bordeaux paste, 

 and the knot usually will not reappear. 



A record of experience in removing root knots is the following 

 by E. O. Amundsen, formerly Farm Adviser of Placer county, but 

 now (1921) Professor of Horticulture in the Transvaal University, 

 South Africa. This is his California experience: 



I have cut out great areas of root-knots from large cherry and plum 

 trees during the growing and dormant seasons and covered with either 

 Bordeaux paste or asphaltum. As the Bordeaux later flakes off and the 

 asphaltum does not, I prefer the latter, but whitewash over it to prevent 

 excessive heat absorption. The asphaltum is an excellent disinfectant, 

 sticks closely, and is cheap. Lately I have used, instead of asphaltum, 

 prepared asphaltum paints or cement paint. These are in liquid form and 

 easier to apply than asphaltum. They dry readily and form a protective 

 coat over the wound. In no case have we had any bad results from cut- 

 ting out crown-gall at any season. Sometimes we do not get all of the 

 gall the first time. We watch it and cut again if any gall shows up on 

 the edges of the wound. 



A systematic treatment of root-knots on almond trees near 

 Chico began in 1918 with chiseling off knots, disinfecting with cor- 

 rosive sublimate solution and covering with asphaltum. Eighty-five 

 per cent of the trees on thirty acres had to be operated on. Two 

 years later only five per cent showed regrowth of knots, the wounds 

 were re-barking and the trees were improved in appearance. It de- 

 pends upon the condition of the tree whether it is worth while to 

 remove the knots or not. If the tree has the start of the knot, it will 

 be helped by removal ; if the knot has the start of the tree so that it 

 is unthrifty, there is small chance of reinvigorating it. This is ap- 

 parently true, both with young and old trees. Old trees are some- 

 times badly knotted and still productive and profitable. 



