Cause The fungus, Rhizoctonia solani, which can survive in soil for many years. Wind and water can move infested soil and plant debris. Rhizoctonia solani becomes active when soil is 77°F to 91°F, attacking any part of the plant underground (soil contact). The fungus is favored by poor soil structure and high soil moisture. Moisture or nutritional stress or injuries can predispose the crop to infection by R. solani. This pathogen can also cause post-emergence damping-off, resulting in reduced stands.
Symptoms Above ground portions of the plant wilt, and plants may die. Lateral roots are absent or entirely decayed. Tap roots are entirely decayed or show large, dark lesions along their entire length. Symptomatic plants are often found in wet areas of the field.
Cultural control
- Plant only on well-drained soil that has a minimum of low areas where water can accumulate.
- Avoid excessive irrigation.
- Practice a 3-year rotation with nonsusceptible crops.
Chemical control
- Dynasty at 0.1 to 0.38 fl oz/100 lb seed plus a dye. 4-hr reentry.
- Maxim 4FS at 0.08 to 0.16 fl oz/100 lb seed plus a dye will help with Rhizoctonia. 12-hr reentry.
- Quadris Flowable at 0.4 to 0.8 fl oz/1,000 row feet applied either in-furrow or as a banded application. May be applied the day of harvest. 4-hr reentry.
Biological control
- Actinovate AG at 3 to 12 oz/A as a soil drench at planting. 4-hr reentry. O
- Actinovate Lawn & Garden at 0.5 to 1 teaspoon/gal water. H O
- Bexfond at 7 to 14 fl oz/A for soil applications via drenches, in-furrow applications, drip irrigation, or sprays followed by irrigation. Reapply 3 to 4 weeks after planting. 4-hr reentry. O
- Double Nickel LC at 0.5 to 4.5 pints/A as a soil drench at planting. 4-hr reentry. O
- Prestop on 3- to 6-week intervals. 4-hr reentry. O
- Romeo at 0.45 to 0.68 lb/A on 7- to 10-day intervals starting prior to infection. Preharvest interval is 0 days. 4-hr reentry. O
- Rootshield WP at 3 to 5 oz/100 gal water for greenhouse soil drench and field chemigation or at 16 to 32 oz/A as an in-furrow spray. 4-hr reentry. O