DISEASES OF PLANTS. 149 



mixture on the first aiipearance of either disease and continuing at intervals 

 of a week until thi-ee applications have been made is suggested. 



The brown rot of the tomato, C. K. Bancroft {Jour. Bd. Agr. [Londoii'\. 

 16 (1910), No. 12, p. 1012). — This is a well-known disease in portions of England 

 in which the fungus attacks the fruits only. An infected fruit first shows dis- 

 colored patches which as the disease progresses run together so that the whole 

 surface becomes discolored while the pulp is reduced to a dark-colored mass. 

 Seeds from infected fruits are of a darker color than normally, because of the 

 presence in the endosperm and embryo of fungal hyphte which appear to be the 

 hyphiB of Phytophtliora omnivora. These infected or "brown seeds" are capa- 

 ble of germination and are reported to produce plants which always bear 

 infected fruits. 



Diseases of trees, L. Savastano {Patolo(/ia Arl^orea Applicata. Naples, 1910, 

 pp. XI -{-666). — This is an elaborate treatise on the common diseases of trees 

 infecting Italian forests and orchards. The author divides the subject into 5 

 general divisions as follows: (1) Biology of trees, (2) constitutional diseases, 

 (3) bacterial diseases, (-1) parasitic diseases, both fungus and insect, and (5) 

 meteorological diseases and silviculture. The work closes with an extended 

 bibliography of Italian literature on diseases of forests and orchards, especially 

 those of grapes, olives, and citrus fruits. Separate indexes are also appended 

 for hosts and parasites. 



[Investigations on crown gall, peach yellows, and other orchard diseases], 

 J. L. Phillips {Rpt. State Ent. and Plant Path. Va., 7 (1908-9), pp. 56-98, 

 pis. 8, flgs. 5, nuips 2). — This paper gives the results of investigations on crown 

 gall of the apple, peach, quince, dwarf pear, dwarf peach, and raspberry ; on 

 peach yellows, peach rosette, little peach, and peach leaf curl ; and on anthrac- 

 nose and rusts of the currant, raspberry, and blackberry. 



After giving the life history of crown gall of apples and the results of various 

 experiments and observations on the nature and dissemination of this disease, 

 the author concludes that crown gall is a bacterial disease which is transmitted 

 to nursery trees by the use of seedlings affected by the hairy root form of the 

 gall and by the use of scions from trees with roots diseased with crown gall. 

 These are the two main sources of infection, although crown gall will also 

 spread from tree to tree in the nursery row. Nurserymen, therefore, should 

 carefully Inspect all seedlings used in propagating apple trees and destroy 

 every one that shows the slightest trace of hairy root and also cut their scions 

 from healthy trees. The lower end of a seedling that is diseased should not be 

 used, even though this lower part is not apparently affected with hairy root, 

 for the disease is in the sap and this lower part will transmit the disease almost 

 as certainly as the upper part. Experiments conducted by the author show in 

 some cases as much as 100 per cent of trees diseasesd with crown gall where 

 scions had been cut from trees affected by this trouble, even when they were 

 inserted into apparently healthy seedlings. 



It has also been shovpn in experiments with thousands of trees that the 

 disease may be reduced as low as from 5 to 10 per cent in the nursery by re- 

 jecting diseased seedlings and scions from diseased trees. Fruit growers are 

 advised to demand absolutely clean-rootetl, healthy trees which have grown 

 in the nursery for 3 years free from the disease, for they can be more certainly 

 depeudetl upon to produce healthy trees than younger stock, as the bulk of this 

 disease does not show up until the third year. 



Remedial treatment, such as the heavy applications of lime, fertilizers, etc., 

 has not proved eflfective in controlling this disease in the nursery, but on the 

 contrary often causes severe injury and in some cases has resulted in the death 

 of trees thus treated. This is true not only of nursery stock, but all orchard 



