Soil Treatments Against Fusarium oxysporum f. sp. vasinfectum Race 4

Few economically feasible disease management options are available for California cotton producers with fields infested with race 4 of Fusarium oxysporum f. sp. vasinfectum.  For treating soil to reduce inoculum levels, past studies indicate that solarization and fumigation with metam-sodium may be affordable, yet effective solutions.  To test their applicability to race 4 in cotton, we compared four soil treatments: a six-week-long summertime solarization, metam-sodium (75 gal/acre), methyl bromide-chloropicrin (50:50, 350 lbs/acre, tarped) and  Telone-chloropicrin (40:60, 31.5 gal/acre, tarped).  The treatments were applied in plots in a field naturally infested with race 4, using a split-plot design, with soil treatment as the whole plot factor and  cotton cultivar as the subplot.  Four cultivars representing a range of susceptibilities to race 4 were used to evaluate the treatments. We will present observations from the first season indicating that soil solarization worked as well as more costly, tarped fumigants (methyl bromide-chloropicrin and Telone-chloropicrin) as evidenced by plant survival.