446 EXPERIMENT STATION RECORD. 



moisture in the soil or to the inabilitj' of the vines previously affected to absorb 

 the amount of water needed. Observations on other vineyards indicate that the 

 trouble is not uncommon, as it is invariably found in situations where the water 

 supply is inadequate. 



Citrus diseases of Florida and Cuba compared with, those of California, 

 H. S. Fawcett (Califoniia Sta. Bill. 262 (1915), pp. 153-192, 200-202, 207-210. 

 figs. 23). — The author compares the citrus diseases of Florida and California, 

 having been connected with the experiment stations of each State for a number 

 of years. Notes are also given of diseases observed in Cuba and the Isle of 

 Pines during a visit to those islands. 



The most widely distributed and probably the most serious citrus diseases 

 of Florida are citrus canker, melanose (with its associated disease, stem-end 

 rot), exanthema, withertip, and foot rot. Of secondary importance are scab, 

 nail-head rust, psorosis, Diplodia gumming, blight, and mottled leaf. In Cali- 

 fornia the most important diseases are brown rot gummosis (with its asso- 

 ciated disease, brown rot of the fruit), mottled leaf, psorosis, and Armillaria 

 root rot, with foot rot, withertip, exanthema, Botrytis gummosis of lemons, 

 and Botrytis and Sclerotinia rots of lemons occupying a less important posi- 

 tion. The characteristics of the different diseases are described, and in a table 

 the diseases, parts affected, occurrence, and treatment are summarized. 



[Citrus diseases at San Pedro in 1915], F. S. Earle and J. M. Rogers 

 (San Pedro [Isle of Pines] Citnis Path. Lab. Ann. Rpt., 1 (1915), pp. 5-11, 21-Jil, 

 figs. 16; abs. in Agr. News [Barbados], 14 (1915), No. 350, p. Si8).— Diseases 

 referred to environment are chlorosis, ascribed in this locality to superfluous 

 soil moisture or inferior nutrition; frenching, thought to be due here chiefly to 

 killing of the root hairs by the sun's heat in unprotected soil, and alleviated 

 by the use of a heavy mulch and a small amount of sodium nitrate; and rarely, 

 Florida dieback in young groves, ascribe<I in part to unfavorable soil conditions. 



Diseases here classed as functional or physiological are fruit gunnnosis, asso- 

 ciated with chlorosis, causing some of the fruit to fall prematurely; blossom- 

 end rot of limes and lemons, from which no organism could be isolated ; spot- 

 ting of the fruit, especially lemons, during artificial curing, and originating 

 presumably in the breaking down of the oil cells; spotting of grapefruit, asso- 

 ciated with insect injury ; splitting of fruit, due here to heavy rains after the 

 fruit ripens ; leaf spotting of citrus trees which are below normal as regards 

 growth conditions or which lack fertilizer ; yellow spotting of leaves on un- 

 thrifty trees due to loss of root hairs and rootlets following continued rains; 

 and greasy spot with accompanying leaf fall, not very serious, but of undeter- 

 mined causation. 



An alga causing a red rust on citrus trees, assigned to the genus Cephaleuros 

 or Mycoidea, is said to be very similar to that causing red rust of tea in India. 



Fungus diseases noted include a scab (Cladosporium eiiri) of fruit and 

 young branches; sooty mold (Fumagn citri) ; a smoky fungus somewhat 

 similar; anthracnose or withertip (CoUctotriehiim glarosporioUlcs) ; Rolf's 

 Sclerotium fungus; blue molds (Penieilliiiiu spp. ). usually more serious on 

 lemons and oranges than on grapefruit; black molds (Miieor spp.) ; Fusarium 

 root rot, traveling up the trunk and causing gimunosis of the trees situated on 

 wet, sandy land; and Diplodia natahusis, considered the worst citrus enemy 

 in this section, and discussed at some length. The Diplodia is thought to be 

 self-limiting by its production of gum, which, when present in sufllcient amount, 

 was found to check the development of the fungus. Painting with carboline\im 

 or an emulsion thereof is the only preventive suggested. The washing tank is 

 thought to be an important source of Diplodia infection of the fruit. 



