EXPEROrENT STATION 1?EP0KT. 549 



Tronliles of Tomatoes Under Glass. 



Leaf Mold. — The chief I'ungous disease of greonliouse tomatoes is 

 llie leaf mold, due to the fungus Cladosporiiim fidvum Cke. This 

 is quickly recognized by the pale, olive-colored, irregular patches upon 

 the under side of the foliage, due to a felt of fungous threads and 

 spores. Soon the infested areas Ijeeouio lu-own, and they are no longer 

 of use to the plant. By means of the multitudes of active spores the 

 mold quickly spreads, and the plants nuiy be ruined. The fruits may 

 be attacked by the same fungus, and undergo a rapid, noisome, watery 

 decay. 



In addition to the spraying recommended elsewhere (page 547) for 

 outdoor tomatoes, it is necessary to have a good circulation of air. 

 Many successful growers are impressed with the importance of train- 

 ing tlie plants high above the soil, even pruning away any branches 

 that form near the benches. 



Dropsy or (Edema. — Many greenhouse plants suffer from a disease 

 which is not associated with any fungus, and appears to be entirely 

 physiological. For example, the common geranium (Pelargonium) 

 is frequently thus attacked, and the writer treated of this malady, 

 jvith an engraving, in a previous report,* and within the past week 

 the same trouble has been met with. 



The first appearance of the trouble is the translucent dots, that 

 may be best seen by holding the tomato leaf up agaijist the light. 

 This subject, in connection with the tomato, has been studied by 

 Professor Atkinson,f and he concludes that the trouble is due to 

 excess of water, favored by insufficient light — that is, a wet soil and 

 a soil-temperature near that of the air. In short, the long nights, 

 short days and cloudy weather of late winter induce the dropsical 

 trouble, especially with a wet, warm soil, thus making root action 

 excessive. The remedy, therefore, is to l)e found, as far as possible, 

 in providing a cooler, dryer soil for the roots, with increased light 

 for the stems and leaves. 



In the winter of 1001-02 there was much of the (Edema in a lot 

 of young tomato plants, in pots, that were standing upon a side shelf 

 of the greenhous<^ and directly over a set of heating-pipes. The soil 



* Report of Botanical Departnjent New Jersey Experiment Station for 1893, pages 

 432-433. 



t<Edema*of the Tomato, Bulletin 53, New York (Cornell) Kxperiment Station, 

 May, 1893. 



