Effects of soil fumigants and aldicarb on corky ringspot disease and trichodorid nematodes in potato.

In 1982 and 1983 the soil fumigants ethylene dibromide (EDB), EDB + chloropicrin, and 1,3-dichloropropene (1,3-D) applied with one or three chisels per row were evaluated singly and in combination with aldicarb on potato, Solanum tuberosum cvs. Atlantic and Sebago, for control of trichodorid nematodes and potato corky ringspot disease (CRS). In 1982 dosages per chisel for EDB, EDB + chloropicrin, and 1,3-D were 16.8, 23.9, and 56.1 liters/ha, respectively. EDB was applied at 12.6 liters per chisel per ha in 1983. Aldicarb was applied at 3.4 kg a.i./ha in-the-row. Differences (P </= 0.05) in the percentages of tubers having CRS and in mean trichodorid population densities were recorded between methods of fumigant application and among fumigants. The reductions in CRS associated with triple-chisel applications compared with single-chisel applications of the fumigants were insufficient to justify their commercial use solely for CRS control. Addition of aldicarb to all fumigation treatments, regardless of the fumigant application method, resulted in highly effective control of CRS. The disease was less severe in Atlantic; however, CRS was sufficiently severe to justify use of aldicarb on either cultivar.