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The Landscape Alerts
Original Source:Alfredo Martinez-Espinoza, UGA Extension Turf Pathologist
Taken from a longer publication - See entire article here
Lawn diseases can be a problem. Despite our best efforts, a fungicide may have to be used. Here are a few tips to get the most benefit from the fungicides that you apply.
Methods to Maximize Efficacy of Turfgrass Fungicides
Read carefully and follow the label directions before applying fungicide.
Apply fungicides at rate specified in the label.
Always follow instructions on the fungicide label for re-entry to the area.
Fungicides are not equally effective on all diseases. Proper fungicide selection is very important for disease management. Consult your local county agent for up-to-date information on latest science-based fungicide efficacy ratings. Additional information can be found at:
www.turffiles.ncsu.edu/Diseases/Default.aspx (info sheets)
The best control is achieved by applying fungicides preventively (before disease is present).
Use compatible tank mixes at recommended label rates.
Use proper sprayer, nozzles and pressure to deliver appropriate coverage. Flat fan or swirl chamber (raindrop) nozzles are most recommended for fungicide applications.
Water pH for dilution or mix should be between 6-7.
Fungicides should stay on the foliage for at least 6 hours for most effective control.
Some fungicides have to be watered-in for proper place of action.
Avoid turfgrass stress (drought or temperature) before or at the time of application. This could interfere with maximum fungicide uptake, activity and efficacy.
Fungicides should be sprayed when air temperatures are between 60°F and 85°F (15°C and 29°C) for best results.
Delay mowing and other cultural practices as much as possible to give the fungicide a chance to work (for proper mowing frequency-follow the one-third rule).
Use enough water when applying fungicide for adequate coverage. Usually 2 gallons water/1000 sq. ft. should give an adequate coverage and deposition.
Do not apply fungicides when conditions are windy to avoid drift and poor coverage. Wind velocity tends to be the lowest early in the morning and late in the afternoon.
When using granular materials, best results are obtained if soil is moist.
Be patient if an application appears to have produced no results. Some fungicide application results can be seen months later.
For pesticide recommendations see the UGA Pest Management Handbook – www.ent.uga.edu/pmh/
For further information contact your local County Extension Office – (800) ASK-UGA1
Photo - Take all root rot – Holly Thornton, UGA, Bugwood.org
Original Source:Dr. Elizabeth Little, Extension Specialist, Dept. of Plant Pathology, UGA
June 19, 2012
Impatiens downy mildew, caused by the ‘fungus-like’ organism Plasmopara obducens, was confirmed in the Georgia piedmont the week of June 15. Two separate samples, one from a landscape and one from a nursery, were received and diagnosed in the clinic. The plants in the landscape had reseeded from the previous year which may indicate that the pathogen is overwintering in Georgia. Downy mildew reproduces and spreads in mild, wet conditions, and the rainy weather of the past few weeks was very conducive for disease development.
All seed or vegetatively-propagated Impatiens walleriana (including double impatiens and mini-impatiens) and any I. walleriana interspecific hybrids are considered susceptible. The downy mildew pathogen can be moved to new areas on infected bedding plants, but once in the landscape the spores can spread long distances to new plantings. The pathogen may also produce oospores that survive the winter between seasons, infecting impatiens planted in the same area the next spring.
Identification: The name downy mildew comes from the white “downy” appearance of the spores that are produced in abundance on the undersides of the leaves during humid conditions. This downy growth is diagnostic for the disease and the pathogen is identified by examining the spore structures microscopically. Early symptoms of the disease can be subtle with a slight yellowing and curling of the leaves. As the disease progresses, the plants will appear stunted and drop their leaves. If you suspect that you have the disease, please contact your local county extension office for confirmation.
Management should focus on early identification and prevention. Purchase disease-free plants and place plants in areas of the landscape with good air circulation to lower humidity. High humidity and more than 4 hours of leaf wetness encourages disease. Water management is important for preventing disease. Avoid overhead sprinkler irrigation whenever possible and water only as needed. Irrigate only on sunny, dry days and early in the day to encourage rapid drying of the foliage.
If infection is found, remove and destroy (bag and throw away) the infected plants and surrounding apparently healthy plants. Fungicide treatments are not recommended for plants in the landscape and fungicides will not eliminate all disease in an infected bed. After removing infected plants, the beds should be replanted with another type of plant both the same season and the following year. Infected plants left in beds may eventually produce oospores that will perpetuate the disease from year to year. Impatiens downy mildew will not infect other species of bedding plants including New Guinea impatiens.
At this time we are tracking the spread and incidence of Impatiens downy mildew in landscapes across the state. Please contact us to confirm the disease. Thanks.
Contact info: Elizabeth Little, Department of Plant Pathology, UGA, Athens