For poinsettias, also very vulnerable to a powdery mildew (Oidium sp.), a biological control program was evaluated in comparison to a fungicide program using new reduced-risk fungicides. This herb is difficult to produce because of its vulnerability to powdery mildew and the scarcity of powdery mildew control materials registered for use on herbs in the greenhouse. A greenhouse experiment tested biological and biorational control treatments in various rotations for their ability to protect rosemary plants from powdery mildew during greenhouse production. Powdery mildew disease control trials with experimental and registered fungicides and biofungicides were undertaken for three years, focusing at various times on the management of diseases of gerbera, verbena, dahlia and poinsettia. These replicated and statistically analyzed trials allowed comparison of verbenas from five different propagation companies rated under uniform environmental conditions. In year one, 23 cultivars were compared and in year two, 33 cultivars were observed. In two greenhouse trials, cultivars of verbena were compared for susceptibility to the powdery mildew Podosphaera xanthiii, which causes losses of sales for verbenas grown as spring bedding plant crops and also attacks squash transplants. Progress 10/01/06 to 09/30/09 Outputs OUTPUTS: Experiments directed at improving control methodology for downy mildew and powdery mildew diseases of greenhouse flower crops were conducted at the Long Island Horticultural Research and Extension Center (LIHREC) over a three-year period. Coleus trials will be conducted in plastic tents with spray-applied inoculum verbena trials will beĬonducted on the greenhouse bench with inoculum supplied naturally from diseased plants grown amidst the experimental plants. Eight single-plant replications of each cultivar will be uniformly exposed to inoculum and then rated for symptom development under greenhouse conditions. Propagation companies producing verbena and coleus will be contacted in fall 20 and asked to contribute their major cultivars for screening. Cultivars of plants with currently problematic DM and PM diseases will be screened for resistance, comparing verbenas for their susceptibility to PM and coleus, perilla and agastache for their susceptibility to DM. These programs will be tested during the spring cropping period in replicated trials. Materials identified as effective in Objectives 2 and 3 will be combined into strategic disease management programs, designed to slow the development of resistance in the PM and DM pathogens. Season-long programs for their ability to control DMs, PMs and other flower crop diseases. Reduced risk and biorational fungicides including the active ingredients azoxystrobin, pyraclostrobin, trifloxystrobin, potassium bicarbonate and biocontrols (plus new materials as they become available) will be tested alone and in Replicated greenhouse trials will be conducted on plants inoculated after protective treatments plants will then be exposed to high-humidity conditions that will allow disease expression. Organic fungicides will be tested for powdery mildew (PM) control on rosemary and DM control on coleus (and other host-pathogen systems if inoculum becomes available).
Dapple Apple will be inoculated with DM conidia and then held at 50-60, 60-80, and 80-90 degrees F under high humidity. To compare disease development in the greenhouse at different seasons. The most popular cultivars of the susceptible species will also be screened for resistance. Impatiens relatives, including balsam and New Guinea impatiens, to explore the host range for the DM of impatiens.
If inoculum becomes available, tests will also be done using ornamental crops that are Initially these trials will be undertaken for other mint family members that might be hosts of coleus downy mildew.
To determine host range for DMs, ornamental crop plants in the same family as the known host will be exposed to inoculum in tents within the greenhouse supplied with high humidity. coleus and impatiens) will be inoculated with downy mildew (DM) prior to transplant, one month after transplant, and at flowering, and the seeds will be harvested, planted and tested for DM. Also, plants of downy mildew susceptible species (e.g. Seed transmissibility will be examined by planting seed from commercial crops in which downy mildew has appeared, and growing young plants in the absence of inoculum in a humid environment.
#Otto keil nursery series#
Project Methods The work will be addressed in a series of greenhouse trials conducted at the Long Island Horticultural Research & Extension Center.