Improvements and Replacements for Pre-Plant Soil Fumigation

High-pressure steam, hot air, hot water, and two years of solarization are ineffective fumigation replacements because heat cannot be distributed adequately through soil. Deeper placement and lower treatment rates with MB can deliver effective nematode control while reducing somewhat the MB volatilization, but control of weed seeds will be lost. Our soil drenching experiments show greatest potential as a replacement. Soil pest control and kill of old peach roots is equivalent to that attained with Telone or MB when 200 gal/ac Vapam is used. However, plant growth following 200 gal/ac does not keep pace with that of MB, Telone, or 100 gal/ac Vapam. One immediate spin-off from the drenching work is that growers already having drippers or planning to install them prior to replanting can use our drenching recipes today. Evaluation of the use of Roundup prior to tree and vine removal indicates that for Nemaguard rootstock the treatment can work well but not for plum roots. Our grape work involves Garlon, 2, 4-D, and Roundup. Rotation crops may have some value if complimentary methods of root kill become usable. Forty days and nights of flooding will not kill nematodes or old roots oiPrunus. Cabernet Sauvignon on Teleki 5C does not grow as well in a replant site as Cabernet on its own roots. It also did not respond as well to the Vapam drench (first year).