1976 



ENCYCLOPEDIA OK PRACTICAL llOKPU'ULTURE 



out. The central portion of tho plants 

 remains green, while the large leaves 

 turn slightly yellow; then in the course 

 of a week or ten days the most severely 

 affected fall over. On examination it is 

 found that the lower part of the stem 

 is hollow. The trouble is caused by forc- 

 ing the plants in the seed bed, and any- 

 thing which induces a soft watery growth 

 is likely to cause hollow stem. Quick 

 growing varieties are more likely to be 

 affected, and transjilanting before hard- 

 ening off the plants is favorable to the 

 trouble. 



G. E. Stone, 

 Massachusetts Bulletin LIS. 



Loaf Blight. Kust 



Cylindrospurium sp. 



Considerable trouble has been exper- 

 ienced with this blight on Long Island* 

 and in New Jersey.** It occurs as brown- 

 ish spots on the leaves, and as the trouble 

 progresses it involves the whole leaf, 

 causing it to turn brown and dry up. 

 In severe cases of infection practically 

 all of the foliage may be destroyed. 



The trouble has occasionally been ob- 

 served on greenhouse tomatoes. 



For field crops spraying has been rec- 

 ommended. In the greenhouse the rem- 

 edy is more simple, since the disease 

 results from too much crowding. 



A similar spot is often found on chrys- 

 anthemums. On botli tomatoes and chrys- 

 anthemums the disease is confined to the 

 lower shaded leaves of closely planted 

 crops, and Is never observed on individ- 

 ual plants of chrysanthemums grown in 

 pots or where light and air have access 

 to the foliage. In the fall and winter, 

 when the light is poor, the lower loaves 

 of crowded plants often deteriorate and 

 show signs of prematurity; consequent- 

 ly becoming more susceptible to disease. 



To prevent this trouble the crop should 

 not be planted too closely, and the foliage 

 should receive more air and sunlight. 

 On too closely planted tomato plants the 



men 

 520 



• New York (Geneva) Aerleultural Ktufir' 

 »nt Station, 14th Annnual Ueport, 1H'.).,. p. 



-• NVw .Tersev Acrldilturfll Kxnerlment Sta- 

 tion, 15th Annual Report. 1804, p. 361. 



lower leaves may be removed, and if 

 diseased, destroyed. The pruning of the 

 lower leaves is not harmful and lets in 

 more light and air where it is needed. 

 Leaf might 

 .^cptoria sp. 

 Leaf blight is frequently seen on field 

 crops of tomatoes. It is reported as 

 being rather serious in New Jersey, Ohio 

 and tlie south, and it has recently caused 

 much trouble in the Middle West. 



This disease is distinguished from 

 other leaf diseases by the presence of 

 circular spots, at first appearing on the 

 lower leaves. The infection increases 

 with the development of the plant, and 

 in severe cases little remains of the plant 

 but bare stems and small, stunted fruit. 

 It yields to treatment with the Bordeaux 

 mixture. The first spraying should be 

 given about two weeks after transplant- 

 ing, followed by two or three additional 

 sprayings at intervals of three weeks. 

 G. E. Stone, 

 Massachusetts Bulletin 138. 



Leaf Mold 



Cladosporium fulvum 

 F. D. Bailey 



This fungous disease is often found on 

 tomatoes when raised under glass. In 

 the South it is sometimes destructive in 

 the open. In the Northwest where green- 

 house men are familiar with it, little 

 concern is felt, for while the foliage is 

 somewhat decreased in efficiency, it at- 

 tacks only the older leaves, and the plants 

 mature a good crop. The yield is pro- 

 ably held down, however, and careful 

 comparative tests will doubtless show 

 the advisability of spraying. 

 Symptoms 



This fungus attacks the older leaves, 

 causing yellow spots to appear on the 

 upper surface. On the lower side these 

 spots are darker in color, and on close 

 examination will be found to be covered 

 with a gray-colored mold or fungus. 

 Many spores capable of spreading the 

 fungus are produced on this growth. Air 

 currents, water or insects furnish means 

 of scattering to other leaves. 



