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During the past tv;o years experiments v/ith soil fumigation in the town 

 o£ Falmouth have resulted in an increase of about 2000 quarts per acre in favor 

 of soil fumigation. The soil was a light sandy loam. Fumigating was done in 

 the early fall. The variety Robinson was used in 1957 and Sparkle in 1958. 

 EDB (ethylene dibromidc) v;as used on the 1957 bed. Several materials were 

 used on the 1958 bed but there was little difference among them. 



A little quick figuring will shov; that in those cases soil fumigation 

 paid quite well, 2000 quarts at 25 cents - this was a common price for "pick 

 your ovm berries" - equals $500, The cost of the commonly used soil fuiuigants 

 is from $50 - $60. Application costs $10 - $20 an acre. Hence, $500 of addi- 

 tional income was produced at a cost of $80 or less. 



Now, lets review a bit what we're talking about. IJhen we say "black root" 

 or "black root rot", we are referring to a condition of the root in which its 

 outer sheath has died and turned black. Sometimes the inner "core" is still alive 

 and white; sometimes it too is dead and black. Regardless of what kills it, the 

 root will turn black. There are many causes for death such as cold, drought, 

 fungus attack and nematode attack. Or death may result from a combination of 

 these causes. There is a good reason to believe that in eastern United States a 

 large part of the "black root" trouble is caused by microscopic worms called 

 nematodes. These attack the roots and, if in sufficient numbers, kill the roots 

 and cause them to turn black.. Therefore, the soil fumigants most commonly used 

 are those that will k.ill nematodes and are called nematocides. There are soil 

 fumigants which will control fungi and weeds in addition to nematodes. These 

 materials are much more expensive and are seldom used in strawberry fields unless 

 some benefit other than nematode control is desired. 



The most commonly used and cheapest soil fumigants for strawberries are D-D 

 and EDB (ethylene dibromide) . These are liquids V7hich are injected into the soil 

 to a depth of six to eight inches in bands ten inches apart. The liquid turns to 

 a gas and permeates the whole soil.. For effective use the soil - not air - temper- 

 ature needs to be between 50 and 80 degrees Fahrenheit. It is also extremely 

 important that the soil be properly prepared before fumigation. All plant remains 

 must be thoroughly decomposed because any which are not can protect nematodes 

 from the fumigant and may accumulate in front of the chisels of the fumigator and 

 cause trouble. The soil must be moist and friable with all clods brolcen up as 

 for a good seed bed. 



Since these soil fumigants are toxic to strawberry plants, it is necessary 

 to wait three weeks after application before setting the plants^ ,p Because of 

 this V7ait and the necessity for having the soil temperature at .Jw degrees, letting 

 the fumigation go till spring may result in very late setting of plants, especially 

 if the spring is late and cold„ Late summer or early fall is a good time to do the 

 job. 



Even the very best job of furaigating will not kill all nematodes in the soil. 

 They v/ill be likely to build up again so that for r.ia::imum protection a repeat treat- 

 ment will be needed each time a strawberry bed is set. 



The benefits of soil fuaiigation can be lost by setting plants which are infected 

 V7ith nematodes. Taking plants for setting from an old fruiting bed is risl.y. It 

 is far better to get plants from a reliable nurseryman v/ho starts out with clean 

 plants and grows them in fuiuigated soil. 



John S. Bailey 



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