144 TOMATO CULTURE 



beginning of the trouble when the eradication of a 

 few wilting plants may save the remainder. 



(3) Control of insects. — To lessen the danger from 

 spread of wilt by insects, the measures advised in the 

 next chapter for the control of leaf-eating insects 

 should be adopted. In this connection it should be 

 mentioned that the use of Bordeaux mixture for leaf 

 blights, as previously recommended, has an additional 

 value in that the coating on the leaves is distasteful 

 to insects and helps to keep them away. 



(4) Seed selection. — Work done at the Florida ex- 

 periment station indicates that resistant varieties may 

 be secured, but there are as yet none in commercial 

 use. This is an important line for experimenters to 

 follow up. There is no proof that the disease is spread 

 through seed from diseased plants. 



Fusarium wilt. — This disease and the one follow- 

 ing resemble the bacterial wilt so closely, as far as ex- 

 ternal characters go, that they are difficult to tell apart. 

 The parasites, however, differ so materially in their 

 nature and life history that the field treatment is quite 

 different. There are also differences in geographical 

 distribution that are important, for while the Fusarium 

 wilt occurs occasionally throughout the southern states, 

 it is known to be of general commercial importance 

 only in southern Florida and southern California. 



The symptoms of the disease are a gradual wilting 

 and dying of the plants, usually in the later stages of 

 their development. Young plants die, however, when 

 the soil infection is severe. There is a browning of 

 the woody portions of the stem, and when a section 

 of this is examined under a compound microscope the 



