474 EXPERIMENT STATION RECORD. 



The results from an experiment with MOO 2-year-old apple trees, selected with care 

 as to uniformity of size and root system, seem to indicate that the disease has no 

 immediate effed on the duration of the life of the tree where other diseases do not 

 intervene. Field observations bear out the conclusion that the disease does not kill 

 the young trees as often as has been previously believed. 



There is frequently found on the roots of apple seedlings, and more rarely on grafted 

 apple trees, a L r all of a softer nature, which may prove to he slightly contagious. This 

 is to he a subject for further investigation. < >n grafted trees most of the galls occur 

 at the lower end of the scion at the point of union with the root. The author states 

 that the work of the previous -J years is being repeated in different localities, in all 

 120,000 apple seedlings and root grafts heing under observation. • 



Observations on some vine diseases in Sonoma County, California, 

 O. Butler (California Sta. Bui. Ins., pp. /a, pi. 1, jigs. J).— Descriptions are given of 

 the red-leaf disease, grape shrivel, and root rot, all of which have been under 

 investigation by the author during the past year or more. 



The red-leaf disease, which was first noticed in 1903, is treated at some length, a 

 description being given of the disease, its relationships and resemblance to other 

 diseases pointed out, and the results of experiments for its control presented. The 

 red-leaf disease may affect the shoots, leaves, peduncles, pedicel, and fruit of the 

 vine; the canes on one side or, more rarely, the entire vine may be attacked. The 

 effect that is produced on these different plant organs is described at length. The 

 disease seems to be more or less closely related to folletage, rougeot, and the Cali- 

 fornia vine disease, most nearly resembling the rougeot. 



Winter and summer spraying experiments have been carried on for the control 

 of this disease, and while the vitality of the vines seemed to be increased, as shown 

 by the greener appearance of the foliage, yet the treated vines did not show any 

 very great improvement over the untreated ones. The author believes that the 

 red-leaf disease is due to the same causes as folletage and rougeot, namely, a dis- 

 turbance of equilibrium between the absorption of water by the roots and its trans- 

 piration by the leaves. An examination of the soil showed that it was very deficient 

 in phosphoric acid, and it is thought that proper fertilization will help the vines to 

 at least withstand the red-leaf disease. 



(irape shrivel is the name given a disease which is characterized by the shrivel- 

 ing of the berries. This shriveling seems to be the most important character of the 

 disease, the symptoms appearing in the leaves being easily referable to drought or 

 imperfect nutrition. The fruit of diseased vines, when it does not shrivel, often 

 ripens prematurely. This prematurely ripened fruit is frequently edible, though at 

 times very distasteful. The disease does not show on the foliage at first, but later 

 is characterized by a discoloration of the leaves, which seems to be caused largely 

 by changes in chlorophyll. Xo external indications are shown on the vines, hut 

 when cut in cross or longitudinal sections the wood and pith show discolorations. 



Experiments carried on with a number of varieties, in which different methods of 

 treatment were tested, have led to the conclusion that the cause of grape shrivel is 

 due to imperfect nutrition. It was found that different varieties and different stocks 

 were affected quite differently, and in combating this disease account must be taken 

 of the affinity between the stock and the graft and of the resistance of the stock to 

 phylloxera. The resistance of the stock to the phylloxera may be heightened by 

 fertilization, but if this is not sufficient a change should be made to a more resistant 

 stock. The use of carbon bisulphid in protecting stocks of low resistance from 

 attacks of phylloxera is not under present conditions considered an economic 

 possibility. 



The root rot is of fungus origin and in its usual form is recognizable by the soft, 

 watery, yellowish-brown woody cylinder, which is more or less permeated w T ith the 

 mycelium of the parasite. The disease usually takes from 2 to 5 years to kill the 



