CONTROL OF RHIZOCTONIA SOLANI IN THE FIELD WITH A LOW DOSAGE OF TOLCLOFOS-METHYL OR FLUTOLANIL
The application of the fungicide in the furrow (during planting of the bulbs) resulted in a similar degree of control of the fungus. With this method only 12.5 kg a.i. per ha is required.
Starting from the fact that pathogenic strains of Rhizoctonia solani differ in their temperature preference for infection of bulbous plants (Doornik, 1981), we investigated the possibility to reduce the dosage further. Warmth-preferring strains are pathogenic in late spring and in the summer, when mainly young bulbs are susceptible to infection. Effective control of these strains was achieved with a dosage of 4 kg a.i. per ha applied on and around bulbs during planting. To control cold-preferring strains that attack young sprouts already in winter and in spring, lower dosages than 12.5 kg a.i. per ha are generally less effective.
Tolclofos-methyl and flutolanil, used in the same dosages, proved to be similarly effective in the control of Rhizoctonia solani. Both compounds can be applied in bulbous crops but flutolanil is not registered yet. The alternate use of both compounds may avoid or delay the selection or development of fungicide-resistant strains of Rhizoctonia solani.