MICHIGAN ACADEMY OF SCIENCE. Ill 



OTHER I'AKASITIC UlSICASES CALSKU liV CLAUOSl'OUl T M SI'. 



Pencil Scab, cansed by the fiin<>\is Cladosporluni carpophUiun^^ 

 is found on the surface of the fruit, but does not penelrale beyond 

 the first layer of epidermal cells to any extent, absorbino- food from 

 its host but not Morkinj^- into the tlesli. The cells directly beneath 

 the fungus threads usually form a cork like laj'er and this harden- 

 ino- of the surface is what causes the cracking of the fruit. 



The fungus usually is controlled by self-boiled lime and sulfur 

 liut Bordeaux mixture is an effective remedy except for the fact 

 that it is likely to injure the fruit. 



Tomato Scab, caused by ('l<i(lospoHiim fulvum, is a disease of the 

 leaf of the tomato, the fungus ])enetrating the host tissues and 

 causing a yellowing of the upper surfaces of the leaves, the conidia 

 being borne on the lower surface; giving it a mildewed appearance. 



Bordeaux mixture is a perfect control for this disease if used 

 early enough in the season, but control when it has progressed far 

 is difficult.i- 



Scaley Bark of Citrus Fruits, caused by the fungus Cladosporium 

 herhanim, var. citricola^^, affects the shoots of citrous trees and 

 causes a flaking out of the barli in the infected portion. The fun- 

 gus penetrates the cambium layer and causes the bark to become 

 brittle and hard. A false cambium often forms beneath, and the 

 infected i)ortion is left between two rings of wood. A gummy sub- 

 stance is usuallj- formed by the destruction of the host cells. 



It affects the rind of the fruit, often causing portions to drop 

 out. The conidia are borne on the surface of both fruit and twigs 

 as in all Cladosporia noted. Bordeaux mixture is recommended 

 as a control. 



Cladospormm citri, or citrus scab causes a superficial injury to 

 the surfaces of the fruit, twigs, and leaves of citrus fruits. It pro- 

 duces small wart-like swellings and penetrates slightly into the tis- 

 sues, the spores being borne on the surface^*. 



Moist weather is very essential for its growth and Bordeaux 

 mixture is recommended for its control. 



Prom the comparison of the above diseases with Cladosporium 

 cucumerinmn, it will be seen that they are all similar in nature, the 

 spores being borne on the surface of the host and the injury merely 

 a superficial one. 



The formation of a gummy product seems to indicate that they 



11. Chester. Del. Agr. Exp. Sta. Rpt. 8. 1895. p. 60. 



12. Massee. Disea.ses of Cult. Plants & Trees. 1913. 

 l.S. Bui. 106. Fla. Agr. Exp. Sta. 1911. 



14. Kill. 8, Div. Veg. Path. & Phvs. 1890. 



