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STRAWBERRY BED FUMIGATION 



Walter E. Knox, Jr., Graduate Assistant 

 Department of Plant Pathology 



Several species of nematodes have been reported to cause in- 

 jury to strawberry plantings; under Massachusetts growing condi- 

 tions, Pratylenchus penetrans , the lesion nematode, appears to be 

 most important. This particular nematode occurs throughout the 

 northeast, and because of its broad host range, which includes 

 many cover crops and a large number of annuals and perennials, it 

 is a potential threat to strawberry growers. 



Symptoms of disease caused by P^. penetrans : 



Lesion nematodes have been implicated in the disease complex 

 known as black root rot of strawberry. The whole plant is affected, 

 but first symptoms are visible on the roots. Brown lesions 1 mil- 

 limeter long appear on the roots, rapidly merging to form a brown 

 to black root system. Often, the outer cylinder of root tissue 

 will slip off, exposing the vascular tissue. Such root damage is 

 usually accompanied by the invasion of bacteria and fungi. Above 

 ground symptoms include generally poor growth, of plants, suscepti- 

 bility to drought, and failure to produce runners. 



Control of Black Root Rot : 



Control is a two-fold operation. Of primary importance is the 

 selection of strawberry stock substantially free from nematode in- 

 fection. Such plants will have white roots free from characteristic 

 lesions. All other attempts at control will fail should infected 

 plants be set in the field 



In order to be effective, most fumigants require that the soil 

 temperature be 60 F or above. Therefore, under our growing condi 

 tions, August or September is the best time to fumigate 



it 



and cold. 



