INFLUENCE OF CHLORIDE AND NITROGEN FORM ON RHIZOCTONIA ROOT AND CROWNROT OF TABLE BEETS

The effect of NaCl combined with Ca(NO3)(2), or (NH4)(2)SO4 was examin ed on table beets (Beta vulgaris) in the presence and absence of Rhizo ctonia solani (anastomosis group 2-2), the cause of Rhizoctonia root a nd crown rot. Transplants of cvs. Detroit Dark Red and Early Wonder gr own in the greenhouse in infested soils and fertilized with Ca(NO3)(2) (10 mmol of N) were 32% larger in dry weight than plants treated with (NH4)(2)SO4 (10 mmol of N). In noninfested soils, a 17% increase in d ry weights was observed for plants treated with Ca(NO3)(2) compared to plants that were fed (NH4)(2)SO4. When NaCl (0.17 mmol) was applied, the mean dry weights increased 40% in noninfested soil and 12% in infe sted soil compared to plants that received no NaCl. No significant int eraction occurred between N fertilizer and NaCl in greenhouse trials. However, in field soils infested with R. solani, NaCl (560 kg/ha) comb ined with (NH4)(2)SO4 (112 kg of N per ha) produced 26 to 47% more roo t yield than when (NH4)(2)SO4 was used alone. In the absence of NaCl, Ca(NO3)(2) suppressed disease more than (NH4)(2)SO4, but adding NaCl t o Ca(NO3)(2) did not increase yield more than Ca(NO3)(2) alone. The Cl salts KCl, CaCl2, and MgCl2 did not significantly differ from NaCl in their ability to increase the dry weight of beets grown in infested s oils. Leaf and root analyses revealed that (NH4)(2)SO4 applications in creased N, P, S, and Mn in tissue more than Ca(NO3)(2) applications. A pplying NaCl increased tissue levels of Na, Cl, and Mn more than in pl ants that were not fed NaCl. All of the Cl salts had the effect of inc reasing concentrations of Cl and Mn in the plant. There was no evidenc e that the Na ion was disease suppressive. Chloride, however, may be o f use in disease management of Rhizoctonia root and crown rot of table beets.