DISEASES OF PLANTS. 655 



The bacterial blight was unusually serious during the i)eriod covered by the 

 report. On many varieties the larger part of the blossoms were killed, in some 

 cases the entire crop being lost. Later considerable twig blight followed. 



The cloudiness of pears, which is characterized by rustiness of the fruit, was 

 investigated, and found to be due to three causes — frost, the use of too strong 

 fungicides, and fungus diseases. In many cases the disease is believed to be 

 due to the after effect of fungus diseases, among the principal of which are 

 attacks of the apple scab fungus. 



In the spraying experiments described, the application of lime-sulphur-salt 

 was found very efficient for the control of the San Jose scale, and Bordeaux 

 mixture for the control of brown rot of plums. The application of Bordeaux 

 mixture to apples and pears caused some rusting of the fruit and spotting of 

 the leaves. This is attributed to the use of too strong a fungicide. Eggplants 

 sprayed with Boi'deaux mixture to which arsenate of lead was added produceil 

 more early fruit and apparently a considerably greater crop. 



Experiments in spraying tomatoes are described in which there was appar- 

 ently little difference between the sprayed and unsp rayed plants until the 

 middle of August, after which time the sprayed plants were decidedly of a 

 more vigorous character. The tabulated results show an increase of about 24 

 per cent of marketable fruit as a result of the spraying. 



In order to test the effect of spraying experiments on strawberries and to- 

 matoes while in bloom, two trials were made, and while the results are some- 

 what contradictory, it does not appear that the spraying had any serious effect 

 on the setting of the fruit. 



A method of making Bordeaux mixture is described which is believed to have 

 some advantages over those generally given. This c<nisists essentially in hav- 

 ing the tank containing either the copper sulphate or the lime nearly full of 

 water before adding the other. Where the copiier sulphate alone was diluted 

 the cohnnn in the cylinder containing the fungicide remained unsejiarated for 

 a much longer time than where both solutions were concentrated. Where both 

 solutions were diluted the fungicide remained in suspension for about the same 

 length of time as when the copper sulphate alone was diluted. 



Notes are given on the preparation of stock solutions of copper sulphate, the 

 expansion of water when copper sulphate is dissolved, and the amount of 

 copper suli)hate in a saturated solution. 



Some important plant diseases of Washington, AV. II. Lawrknck ( ]Va.sliin(/- 

 ton 8tn. Bui. 83, pi). 56, figs. IS). — A number of the more important plant dis- 

 eases which have been observed in Washington are descril)ed and suggestions 

 given for their prevention, as far as means are known. Among the diseases are 

 the club root of cabbage, crown gall of various plants, fire blight of pears, late 

 blight of potatoes, i^ach leaf curl, apple and pear scab, blackspot canker of 

 apples, potato scab, canker of soft maple, brown i-ot of stone fruits, dry rot of 

 potatoes, wheat smut, root rot of prunes, etc. 



Among these diseases are a number that are not commonly met with in this 

 country. Of these the principal diseases are the blackspot canker of apple trees 

 due to Myxosporium curinspornm, the canker of soft maple caused by Tubercu- 

 laria vulgaris, and the root rot of prune trees due to AnncUaria mellea. 



The blackspot canker is said to be next in importance to the apple scab in 

 western Washington. The fungus lives in the bark of the tree for about a 

 year and then dies. The low temperature and abundant moisture in October 

 ;ind November favor the germination of the fungus, which enters through the 

 hark. The infected spots increase slowly as the fungus penetrates into the sap 

 wood. When the trees begin to unfold their leaves in the spring the cankers 



