Red leaf spot is a disease that primarily affects bentgrasses and bluegrasses during the spring months. This disease thrives in cool and wet (10°C) weather under overcast conditions. During extended periods of overcast weather, the pathogen will aggressively sporulate and disperse long distances across the golf course. These spores are spread through rain splash or wind, or mechanically by equipment and traffic.
Most often the damage will appear as diffused areas of off-colored turf. In some instances, the damage may appear more localized, primarily due to differences in biotype susceptibility on older bentgrass putting greens. The sward symptoms will include a bronzing of the canopy or a reddish-brown tint, and individual blades may be covered with small, darkened lesions.
Although major injury due to red leaf spot is rare, there are significant consequences to infection. The darkened lesions that drape the leaf tissue can hinder photosynthetic efficiency. In the spring, this can have indirect consequences because the plant is trying to capture as much energy as possible for continued shoot and root growth.
Early detection is critical in managing all diseases, and red leaf spot is no exception. It is recommended to start scouting in areas that are in a compromised environment, such as shaded locations. Finding lesions can be challenging because of how short putting green turf is usually maintained. For this reason, it is important to scout for red leaf spot before mowing. Another trick is to scout in nearby collars, as the longer leaf tissue in the collar gives you a better chance of finding distinct lesions.
- Raise the mowing height and mow regularly to prevent scalping.
- Maintain adequate fertilization to encourage recovery from disease.
- Reduce leaf wetness periods by improving air movement.
- If plants are experiencing heat and drought, syringe the turf to prevent stress and wilt.
- Introduce new cultivars of creeping bentgrass that are more resistant to leaf spot injury.
Dedicate Stressgard™ provides two modes of action (DMI + QoI) that offer tremendous activity against leaf spot diseases. One of the benefits of using Dedicate Stressgard is that it provides both preventative and curative control of leaf spot. It is also active across several other diseases that can occur in the spring, such as Microdochium patch or early season anthracnose and dollar spot.
For more information about disease and insect control strategies, contact your local Territory Sales Manager.@BayerGolfCA
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