1980 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



sued is tlie development of a resistant 

 strain. Tlie grower first selects several 

 desirable varieties. These are planted 

 where it is known that the disease has 

 appeared previously, and from any plants 

 that mature fruit, seed is saved, Mark 

 especially any plants that show resistance 

 to the wilt and take the seed from several 

 tomatoes on such plants. The following 

 season this method is followed out again, 

 using the seed saved from the seeming- 

 ly resistant plants. After several years 

 of careful selecting, a strain should be 

 obtained which will retain the character 

 of resistance. 



White Mold 

 Eriophyes calacladopnora 



This is a disease of the tomato char- 

 acterized by general fuzziness. In its first 

 stages it may be recognized from the 

 following description by P. H. Rolfs: 



If one is standing in a tomato field 

 shortly after sunrise, or near sunset, and 

 looking across the field in the direction 

 of the sun, the plants which are attacked 

 will be easily distinguished from the 

 others in the field by a peculiar white, 

 fuzzzy appearance of the upper portion 

 of the stem. 



In spite of its name "mold," it is not 

 caused by a fungus parasite, but, as was 

 determined by P. H. Rolfs in 1892, by a 

 small mite, closely related to the rust 

 mite of citrus. This mite is almost pe- 

 culiar to Florida, although it occurs as far 

 north as South Carolina. 



The remedy is the same as for its close 

 relative, the mite of citrus; that is, sul- 

 phur. In this case the sulphur is best 

 used as a spray, which must be thorough- 

 ly applied. 



Caustic soda (98 per cent), 10 pounds; 

 flowers of sulphur, 20 pounds; water, 20 

 gallons. 



Mix the sulphur in cold water to a 

 thick paste, add the soda, and as it boils 

 add water gradually to make 20 gallons. 

 This water should be added fast enough 

 to prevent burning, but not fast enough 

 to stop boiling. The result will be a 

 dark coffee-colored liquid. Strain through 

 a fine-meshed cloth or spray-strainer. 



Keep in tightly-corked jugs. Mix one-half 

 gallon of this stock solution in 40 gallons 

 of water when ready to use. Other good 

 remedies are: lime-sulphur solution, dry 

 sulphur and dry sulphur and lime. 



J. R. Watson, 

 Florida Bulletin 112. 



Wilt or Slimmer Blight 



F. D. Bailey 



This disease is very much like the 

 Western tomato blight in many respects, 

 but should not be confused with it. It is 

 described as occurring throughout Cali- 

 fornia, and, in some instances, causing 

 a total loss of the plants in a field. 



In Oregon occasional reports, of what 

 is quite certainly this disease, have come 

 from the southern part of the state. 



Symptoms 



The trouble makes its appearance in the 

 early summer. Often the plants are quite 

 large and fruit is set before the disease 

 begins to appear. Scattering plants 

 through the field are the first to appear 

 sickly; these gradually fall behind the 

 rest in growth, take on an unhealthy color 

 and finally wilt. The wilting is at first 

 noticeable during the hot part of the day 

 only, but as the disease progresses, the 

 plant finally collapses entirely. This 

 condition may continue to spread through 

 the summer until very few or no plants 

 are left. 



Cause 



The cause of this disease is a species 

 of Fusarium, a common soil fungus. This 

 fungus attacks the roots from below the 

 surface of the soil and causes a root rot. 

 It also enters the conductive tissues of 

 the plant, where it spreads and plugs 

 the vessels so that the water supply is 

 prevented from reaching the top, and as 

 a result the plant wilts. 



Treatment 



As regards control measures little of 

 value can be recommended. In some 

 cases it may be advisable to sterilize the 

 soil in the seed beds in regions where the 

 trouble is prevalent. This method would 

 not generally prove practical, however, 

 and the use of new land, when possible, 

 is to be preferred. 



