154 EXPERIMENT STATION RECORD. [Vol 37 



season approaches it is retarded, aud in midsummer it seems to be entirely 

 quiescent. The organism, which is a bacterium, does not appear to be able to 

 penetrate into the wood, and in some cases the cambium is not liilled. Where 

 trees contain a large amount of weak growth in the interior this is badly 

 attacked and the bark rots away, leaving the interior of the tree full of dead, 

 white twigs which are very resistant to furtlier decay. 



Some experiments are said to have been begun for the control of this disease, 

 employing the methods used in pear blight control in California. 



A new bacterial citrus disease, H. A. Lee {U. S. Dept. Agr., Jour. Afjr. Re- 

 search, .9 {I'Jll), Xo. J, pp. 1-8, pis. 3). — In a contribution from the California 

 Experiment Station the autlior de.scribes a new (llsea.<;e of citrus trees which is 

 endemic to the citrus regions of northern and central California, previous 

 accounts of this disease having been note<l above. 



In the author's investigations, sections of fresh, diseased material .showed a 

 bacterial organism present en masse. The organism has been isolated and the 

 disea.se produced by inoculation experiments. A technical description of the 

 organism. Bacterium citrarcfariens n. sp., is given and Its morphological and 

 physiological characters are detailed at some length. 



The cause of June drop of navel oranges, J. E. Coit and R. W. Honr,.soN 

 (Univ. Cal. Jour. Agr., J, (191G), No. 1, pp. 8-10. 27-29, figs. 5).— The authors 

 give a brief preliminary report of studies on the shedding of young fruits by 

 orange trees in spring, which was excessive in 1916 despite good conditions as 

 regards both weather and soil. 



The dropped fruits in practically every test developed Alternaria. the cause 

 of black rot. This fungus, the spores of which are deposited on the stigma 

 in some way not yet determined, grows down to the base of the orange, infect- 

 ing the portions of the old mutilated .style which are left between the main 

 fruit and the diminutive secondary fruit which pushes up through it to form 

 the so-called navel. Valencia oranges, in which the old style breaks away 

 clean, do not suffer from black rot or from exce.sslve June dr(>i>. 



The resistance of the fruit restrains for some time the dovelopment of the 

 fungus and the fruit may reach its maturity and ripen without developing out- 

 wardly the black rot, though inferte<l with Alternaria. Experiment shows that 

 when tran>5piration is rapid, as in dry weather or district.s, water is drawn back 

 from the fruits by the leaves. The enzyms pnxluced by the fungus probably 

 poi-son and weaken the leaf and other cell tissues of the plant, in particular 

 causing the formation of a cork layer and leading to the fall of the fruit. 

 It is suggested that the navel-end splits occurring in fruits in the interior 

 valleys may also be due to Alternaria. 



Experiments looking to the control of June drop are under way and the 

 distribution of the fungus also seems to req\iire fiirtlier Investigation. 



Spraying for ripe rot of the plantain fruit. J. F. PASTrK (.l.'7r. ./oi/r. India, 

 11 {1016), No. 2, pp. 1I,2-1!,9. figs. 2).— It is stated that ripe rot {Glceospnrium 

 musarum) of the plantain, while affecting chiefly stored fruits, may also appear 

 on young fruits, generally near the di.stal end, supposedly arising In most 

 cases from early infection at the style. Although spores germinated In water 

 do not survive desiccation, some of those remaining in the ascervuli may ger- 

 minate after nine months. 



Experiments for three years on a restrictefl scale appear to show that 

 spraying only when the fruit is picked, or even after it is half grown. Is useless, 

 but Biirgundy mixture used monthly Is found to control the disease. How- 

 ever, as this tends to leave bluish specks on freshly sprayed fruits, the 

 last sitraying is more satisfactorily done with ammoniacal copper carbonate. 



