37 



deaux mixture constitutes an effective means for the prevention of 

 this Mildew. Where outdoor crops were sprayed once in two weeks 

 between July 15 and August i. this disease was almost entirely pre- 

 vented. In case indoor cucumbers are planted in August and have 

 become infected, it would be well to spray the under side of the 

 leaves a few times with Bordeaux mixture, made after the 4-4-50 

 formula. As a means of preventing infection v.e would advise keep- 

 ing the vines as free from moisture as possible. In support of this 

 method of prevention it may be stated that two crops of melons 

 were grown in our house the past season without the slightest trace 

 of Mildew, whereas outdoor crops were invariably infected with 

 Plas7nopara. The foliage during the summer months was kept 

 entirely free from moisture. Another method of prevention would 

 be to plant late, preferably in September and October, when the Mil- 

 dew has apparently gone by. 



Timber Rot. 

 (Sclerotinia Libertiana, Fckl.) 

 This disease is common to cucumbers and tomatoes, 

 the stem, causing a shrivelled, dry. and lifeless appear- 

 ance of that portion affected. It also sometimes 

 attacks the fruit. Black masses, or sclerotia. which 

 are about 3V to ^ inch in diameter, appear on the 

 surface of the affected region (see fig. 12). These 

 will germinate and infect other plants, if the con- 

 ditions are favorable. The fungus which produces 

 the timber rot is a soil fungus apparently not 

 commonly propagated by spores, and is believed 

 to be the same as that which causes the so-called 

 " drop '" in lettuce. It does not, however, as a rule. 

 cause very much damage to cucumbers and toma- 

 toes. We have grown tomato plants for five years 

 in soil which was so badly infested with this fungus 

 that nearly one hundred per cent of the lettuce 

 plants would succumb to Drop. In only a few 



It attacks 



Fig. 12. Timber 

 rot on stem. 



Note. — A discussion of the life history of this fungous is given by my colleague. R. E. 

 Smith, in the Botanical Gazette. Vol. XXIX, No. 6, 190c. 



For a discussion of the results of scil sterilization consult 14th annual report of the 

 Hatch Experiment Station 1902. p. 74. 



