456 EXPERIMENT STATION RECORD. 



1.21), self-boiled lime-sulphur (S : S : 50), atomic sulphur (9 : 35), Pyrox (1 : 20), 

 and Sulfocide (1 : 400). Detailed results are given of the effects on the foliage 

 of the various mixtures used, the effect of 1 early application of diluted con- 

 centrated lime-sulphur upon i)oach scab, the efCect of early and late applications 

 of self-boiled lime-sulphur, the effect of an early spraying with a soluble lime- 

 sulphur followed by a second application of a soluble or self-boiled lime-sulphur, 

 the effect of an early application of self-boiled lime-sulphur followed by an 

 application of a diluted lime-sulphur and a self-boiled lime-sulphur, the effect of 

 spraying young trees, and the effect upon brown rot of spraying to control peach 

 scab. 



As a result of these experiments it is claimed that it is unsafe to apply com- 

 mercial concentrated lime-sulphur mixtures to iieach foliage unless more dilute 

 than 1 : 12.5, and some brands even burn the foliage when applied at this 

 strength. Commercial lime-sulphur mixtures when diluted 1 : 150 or 1 : 175 do 

 not injure the peach foliage, but have little effect upon peach scab. The atomic 

 sulphur (a finely divided sulphur containing arsenate of lead) gave promising 

 results against peach scab. It is held that the key to the control of peach scab 

 is having a finely divided sulphur well distributed upon the leaves and fruit 

 during a certain period. The authors, therefore, recommend that for the control 

 of peach scab and brown rot 3 applications of the self-boiled lime-sulphur mix- 

 ture be made, the first application just before the calyx is shed, and the other 

 2 at intervals of about 3 weeks. 



A g-um-inducing Diplodia of peach, and orange, H. S. Fawcett and O. F. 

 BxjEGER (Mycniogia, 3 (1911), No. 3, pp. 151-153). — A preliminary report is 

 made on the isolation of a species of Diplodia from both peach and orange trees 

 ta Florida and of successful inoculations with pure mycelial cultures of the 

 fangus which produced a copious gumming on healthy individuals of these 

 2 hosts. 



The fungus was isolated from the interior of gummy peach branches obtained 

 in 5 different counties in Florida, and also from gummy orange branches and 

 decaying orange fruits. Ten series of experiments, including direct and cross 

 inoculations on both hosts and covering a period of 5 months, were made by 

 introducing pure mycelial cultures into cuts in the bark of 2-year-old peach 

 trees and 1 to 3 year-old orange trees grown in pots in the greenhouse. Every 

 l^each tree thus inoculated developed gumming in from 4 to 7 days, and in one 

 instance a deadened area was produced on the bark from which in 16 days 

 after inoculation the pycnidia of the Diplodia developed. When bits of myce- 

 lium were placed in contact with uninjured bark of tender and green twigs, 

 gumming was induced. In most instances the inoculations on the orange 

 trees produced gum flow, while the cross inoculations from peach to orange 

 and from orange to peach were successful in every instance. 



The same fungus was also isolated from the rotting fruits of orange and 

 grape-fruit, and was shown by inoculation experiments to produce a softness 

 and decay of oranges, lemons, and apples. Portions of the fungus placed on 

 the stalk end of plucked lemons and oranges produced decay, and the fungus 

 was subsequently isolated from the interior of these finiits. 



The microscopic morphology of the fungus agrees quite well with that of 

 D. natalensis, which causes a decay in lemons and other citrus fruits in the 

 Transvaal (E. g. R., 24, p. 157). 



Report of assistant plant physiologist, B. F. Floyd (Florida Sta. Rpt. 

 1910, pp. LXVI-LXXVIII, figs. Ii). — The work during the year has been a 

 continuation of previous investigations on the abnormal tissues of citrus trees 

 affected with die-back, melanose, yellow spotting, and frenching (E. S. R., 

 23, p. 447). 



