6 MASS.'^.EXPERIMENT STATION BULLETIN 393 



scarlet red, uniform at maturity but progressing toward the stem end; during the 

 ripening process yellow green or chrysolite green about the stem end and ochraceous 

 orange or ochraceous buff below, changing to flame scarlet, and finally to a uniform 

 brilliant scarlet. Skin yellow. 



Fruit Interior 



Outer and inner walls medium thick, typically 34 inch in thickness and uniform, 

 light coral red or peach red to scarlet red. Coloring cf inner walls retarded. Cells 

 3 or usually 4, regular in shape and arranged as segments of a circle. Central 

 mass well-defined and firm; the core medium, palei , slightly green or retarded 

 in coloring. 



Lobes of placentae opposite each other and usually 4, 1 to each cell; cells 

 large, moderately filled with pulp and seed. Seeds medium in numbers per 

 fruit and per un"t weight of fruit. 



Miscellaneous 



In Massachusetts resistant to certain forms of tomato leaf mold caused by the 

 fungus Cladosporium fulvum Cke. For commeicinl market use and considered 

 to be a good shipper and keeper. 



ANOTHER FORM OF CLADOSPORIUM LEAF MOLD 



In the fall of 1940 a serious attack of leaf mold occurred on the Bay State to- 

 mato in a Swansea (Massachusetts) greenhouse. Previously in this place and 

 elsewhere Bay State had been highly resistant. 



Earlier in 1940, Alexander-'(3) reported Bay State, Vetomold, Glcbelle, and 

 Red Currant susceptible to another physiologic form of leaf mold. Vetomold 

 is a red fruiting, leaf mold resistant type originated by Langford (9), and Globelle 

 a pink fruiting resistant type originated by Alexander (1, 2). Both were derived 

 from Z. pimpinellifolium (Jusl.) Mill, which originally was found tc be highly 

 resistant or for all practical purposes immune to the Cladosporium fungus. 



Material of the leaf mold from Swansea was used for artificial infection pur- 

 poses at Waltham. Bay State, Vetomold, Globelle, and Red Currant, which 

 had always been highly resistant in previous performances, were in this test 

 susceptible. On Red Currant, necrotic foliage infection areas were numerous 

 and were covered on the lower surface with a considerable growth of leal meld. 

 Heretofore, such a phenomenon en Red Currant had not been observed. The 

 progress of the disease was, however, much less serious on Red Currant than on 

 Bay State, Vetomold, and Globelle. The new form of Cladosporium has appeared 

 in other locations in Massachusetts. It is less virulent and destructive on Bay 

 State than the prevalent, normal form of leaf mold on Waltham Forcing and 

 other locally grown varieties. 



The disease caused by this new form advances slowly from points of infection, 

 giving rise to yellowish infection flecks between which the normal green color is 

 retained for a time, producing the eflfect of a checkerboard. Molding and spcr- 

 ulation on the lower surfaces of the leaves is less abundant, or is delayed at least 

 for some time where desirable watering, heating, and ventilating practices are 

 followed. Where excessively damp conditions are encouraged or disregarded, 

 the tomato plants ultimately become seriously affected. The fact that the new 

 form of leaf mold is not now generally prevalent, and seems less virulent than the 

 original form, would appear to render the status of these derivatives of "pimpi- 

 nellifolium" X "escule.'itum" crosses encouraging. 



'Correspondence, February 16, 1940. 



