Evaluation of registered and experimental fungicides for control of Rhizoctonia root rot of zinnia, 2014

摘要

Inoculum was prepared by growing R. solani on potato dextrose agar for 4 wk. Flasks filled with two parts millet and one part water were sterilized. Four 1.5-in. plugs of the infested agar were then placed into each flask. The infested millet was allowed to grow for three weeks before being mixed (8 oz/1 ft3) into a soilless media (Suremix, MI Grower Products Inc, Galesburg MI). Six-week-old healthy zinnia 'Exquisite Pink' seedlings were transplanted into 4-in. pots containing the infested soilless media on 16 Jun. Fungicides were applied as a drench in sufficient volume to displace 10% of the water (ca. 3 fl oz/pot) on 17 Jun. Six plants per treatment were placed into a completely randomized design. Plants were watered as needed and fertilized three times weekly with 200 ppm of Peters 20-20-20 water soluble fertilizer (The Scotts Company, Marysville, OH). Greenhouses temperatures averaged 81°F during the day and 71°F at night. A plant health rating and the percentage of dead plants were assessedon 23 Jun and 3 Jul.