herbicides should be applied so only a minimum of spray comes in con- 

 tact with bases of plants. 



(2) For control of annual weeds between rows: DNBP at 2 pounds or PCP 

 at 4 pounds in 50 gallons of aromatic oil per acre. A low-pressure sprayer 

 with a hooded boom should be used to prevent spray drift from coming in 

 contact with nursery crops. 



Comments and precautions.- -Perennial weeds are not controlled by 

 these treatments. 



Seedbeds and Transplant Beds 



(1) For control of most annual and perennial weeds: Methyl bromide at 

 1 pound per 100 square feet applied under a plastic airtight cover. Cover 

 may be removed after 24 hours. Methyl bromide does not persist in soil, 

 and plantings may be made safely within 72 hours after removing plastic 

 cover. Soil fumigants are now available for application as drenches at a 

 stated period prior to planting. Plastic or other covers are not required. 

 Examples of materials of this type are 3,5-dimethyltetrahydro- 1 ,3,5,2-H- 

 thiadiazine-2-thione and sodium-N-methyl dithiocarbamate dihydrate. 

 Other soil fumigants and steam sterilization also may be used effectively 

 to control weeds in seedbeds and transplant beds. 



(2) For control of most weeds germinating in upper 4 inches of soil: 

 Calcium cyanamide at 50 to 75 pounds per 1,000 square feet applied to 

 surface of soil and worked into the upper 2 to 3 inches of soil. Seeding or 

 transplanting after using calcium cyanamide should be delayed for 3 to 6 

 weeks to avoid residual toxic effects of the treatment. 



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