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FUMIGATING THE SOIL FOR STRAWBERRIES 



The primary purpose of soil fumigation is to keep healthy strawberry plants 

 healthy. It can't make healthy plants out of sick ones. If sick plants are set 

 in a fumigated field, the benefits of soil fumigation are lost. Buying cheap 

 plants just anywhere is poor economy, even in unfumigated fields; in fumigated 

 fields it may waste the cost of fumigation. High quality, disease free plants 

 will almost always grow faster and produce more than ordinary stocks of plaxits. 



How far can soil fumigation go toward keeping strawberry plants healthy? 

 Obviously it is aimed at diseases which are soil borne and affect the roots of 

 the plants. Any effect it has on the tops is the result of changes in the gen- 

 eral health of the plant brought about by the soil fumigation. 



There are several soil borne diseases but only two are presently of economic 

 importance in Massachusetts; red stele and black root rot. Soil fumigation for 

 the control of red stele is still very much in the experimental stage. Several 

 materials have looked promising under certain conditions but they are expensive 

 and not yet certain. Yields must be high to make them profitable. 



Black root, on the other hand, can and has been controlled by several ma- 

 terials, some of which are cheap enough to make their use profitable without 

 excessively high yields. A number of growers have found D-D and ethylene 

 dibromide reasonable in cost and quite effective. In experiments last summer, 

 these materials gave yield increases of from 10 to 20 percent. These materials 

 are chiefly nematocides. If the plants in a field have previously suffered 

 from nematodes, these should help. 



If, on the other hand, the trouble is caused by a fungus, then it will be 

 necessary to add a soil fungicide to one of these nematocides or use a soil 

 fumigant which is both a nematocide and fungicide such as methyl bromide, 

 chloropicrin or Vapam (VPM) . These materials are expensive to purchase and 

 apply with the exception of Vapam, which can be applied through an irrigation 

 system. In addition, however, these do have what might be called a bonus benefit 

 because they give considerable weed control. If chemical weed control is wanted 

 in addition to soil disease control, then the high price of these materials may 

 be justified. Obviously Mr. Teeling (refer to story by Mr. Teeling in this 

 publication) found the combination of weed control and disease control profitable 

 or he wouldn't have continued using one of these expensive materials. 



Whatever material is used, thorough and timely soil preparation is necessary 

 for good results. Frequently, this is overlooked or forgotten. Plowing should 

 be done far enough in advance so that all plant remains, such as grass, weeds, 

 corn stubble, etc., which harbor nematodes are completely broken down. Without 

 time for this sort of material to decompose, soil fumigation cannot be thoroughly 

 effective. The soil should be well pulverized, loose, friable, moist and above 

 50 F, that is, in seed bed condition when the application is made. After 

 application, time must be allowed for all traces of the fumigant to disappear 

 from the soil before planting. This takes three to four weeks with most soil 

 fumigants, however, only seven days are required with methyl bromide. 



