2026 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



sections of the country. Once established 

 in a field, it will live there for years and 

 kill off the plants whenever watermelons 

 are planted in it. 



The disease is quite generally distrib- 

 uted throughout the southeastern part of 

 the United States and has been reported 

 from Iowa, Indiana, Arizona, Oklahoma 

 and California. It is also destructive 

 in some parts of Oregon. 



Symptoms 



The name indicates the characteristic 

 symptoms, the wilting and drooping of 

 the foliage as though the water supply 

 were cut off (Pig. 1). This wilting 

 comes on suddenly and in a very short 

 time the plant is dead. If the main stem 

 of a wilted plant be cut in cross section, 

 the woody part is found to be yellow and 

 discolored, making a marked contrast 

 with the normal plant in which the tis- 

 sues are uniformally white. Sometimes 

 a pinkish, mold-like growth comes out 

 on the surface of the stem soon after 

 the plant is killed, extending for a foot 

 or more up the stem from the crown. 



Cause 



This wilt is caused by a Fusarium, a 

 fungus which is capable of living in the 

 soil for several years, and may attack 

 any melon plants that are afterwards 

 planted in fields where it exists. This 

 fungus is composed of a very delicate, 

 branching thread-like growth, so delicate, 

 indeed, that its presence could not be 

 detected in the soil. This growth, on 

 coming in contact with the tender roots 

 of the melon plant, is able to penetrate 

 them, and, once within the tissues of the 



plant, it finds the proper nourishment 

 for rapid growth. Very small spores are 

 produced and set free in the vessels, 

 where they germinate to start new points 

 of infection. These spores, having ger- 

 minated, produce a growth which plugs 

 up the vessels and so prevents sap flow. 

 This condition results in wilt and in the 

 death of the plant. The fungus rapidly 

 spreads through the roots and older part 

 of the vine, often coming to the surface 

 where another and larger kind of spore 

 than those formed within the vessels 

 may be produced in great numbers. These 

 spores are readily carried by wind or 

 insects, thus helping to scatter the dis- 

 ease over wide areas. 



Another way in which this disease is 

 frequently spread to new fields is through 

 the application of manure. Diseased 

 plants frequently are carried to the com- 

 post heap. It is also claimed that the 

 fungus spores are not killed when pass- 

 ing through the alimentary canal of 

 cattle. It is, therefore, necessary to avoid 

 any chance for cattle to pasture on wilted 

 vines. 



Treatment 



Take every precaution, in the first 

 place, to keep the disease from spreading 

 to new fields. Tools used in a field where 

 the disease is found should be cleaned 

 and sterilized before using them in 

 ground free from trouble. Do not drive 

 or walk directly from the one to the other 

 or allow soil to be transferred, as might 

 be the case where irrigation is practiced. 

 Keep the compost heap free from the 

 fungus. If doubtful on this point, it 

 would be advisable to try fertilizing a 



Fig. 1, Watermelon Wilt, a Serious Disease in Some Sections. 



by a soil fungus. 



This disease is caused 



