36 



surface and usually bring about a cure. The latter has been 

 found an effective treatment in many instances. Good drainage 

 is also beneficial in such cases. 



SCAB OR VERRUCOSIS OF THE LEMON AND OTHER CITRUS FRUITS. 



The introduction of this disease into the United States is 

 comparatively recent. It first appeared in Florida ab »ut the 

 year 1884, and spread rapidly over the State and to Louisiana. 

 Although many thousands of trees affected with scab have 

 been sent to California, it seems that the disease is unable to 

 exist there permanently. The reason for this will appear later. 

 The malady also occurs in Australia and Japan, from which 

 latter country it was undoubtedly introduced into America. 

 So far it is not known to occur in Europe or Africa. The first 

 account of the disease was published by F. Lamson-Scribner in 

 October, 1886, (Bulletin of the Torrey Botanical Club, New 

 York, Vol. XIII., No. 10, p.p. 181 — 183), at which time Pro- 

 fessor Scribner was chief of the section of Vegetable Pathology 

 of the Department of Agriculture. A fuller account, with a 

 coloured plate, was published in the Annual Report of the 

 Commissioner of Agriculture for 1886, p.p. 120, 121. A disease 

 undoubtedly the same was reported from Australia on orange 

 and lemon leaves by Henry Tyron (1). 



The principal loss from scab occurs in Florida, where it often 

 rendei'S lemon groves so unprofitable that they are cut off and 

 budded to other citrus fruits. In many cases a very large per- 

 centage of the fruit is rendered unsaleable, sometimes one-third 

 or even one-half being unfit for market. It also causes some 

 injury to sour orange trees (before they are budded) when 

 grown for nursery stock. 



Scab, or a disease closely allied to it, occurs on very young 

 fruit of the lime (Citrus limetta), and in some localities is 

 often so severe as to entirely destroy the crop. For example, a 

 grove in tropical Florida, capable of yielding 500 boxes of fruit 

 annually, when attacked by this disease produced for several 

 years only a few hundred fruits, and the majority of these fell 

 off while still very young. In Louisiana it is said to have 

 attacked Satsuma oranges ; in Japan it causes considerable 

 damage to orange groves situated on low moist land ; in 

 Australia it is reported as causing orange and lemon trees to 

 lose their leaves and to yield poor crops, badly affected trees 

 often not setting a single fruit. Probably the annual loss from 

 scab in the United States is not far from $50,000, most of the 

 damage being done to the lemon in Florida. 



(1) Report on Insect and Fungus Pests, No. 1, Queensland, 1889, p.p. 

 144, 145. 



