Several minor, late season turf diseases have been reported found on lawns recently. Leaf spot and blight diseases such as Colletotrichum, Curvularia, Leptosphaerulina, and Ascochyta often develop as the result of long-term exposure to stress, like the end of summer that had variable periods of precipitation and high soil and air temperatures, such as the one we are currently wrapping up. Soil compaction, excessive thatch, infrequent irrigation or watering that is too light and mowing to shorter blade heights than recommended can also leave turfgrass susceptible to infection. Secondary pathogens may also be present, including fungi which target root systems and nematodes.
All of the above-mentioned fungal diseases will live in the thatch and symptoms may be worse in areas with heavy traffic, soil compaction and/or poor drainage. Infection occurs through cut blades of freshly mown turf. Colletotrichum is most common on bluegrass and bentgrass species, while Curvularia, Leptosphaerulina and Ascochyta will infect almost any grass species. Additionally Curvularia, Leptosphaerulina and Ascochyta may develop in the presence of excessive nitrogen while Colletotrichum development favors inadequate amounts of nitrogen.
Some steps to take to avoid infection or decrease susceptibility include, but are not limited to:
- Fertilize properly- Use the appropriate product for the season as well as specifically for your lawn. Nutrient deficiency or excess can be diagnosed via a soil test and evaluation performed by your arborist, if necessary.
- Avoid soil compaction- Try to reduce soil compaction by keeping foot traffic to a minimum and not driving or parking vehicles or equipment on lawn areas. A core aeration may relieve soil compaction already present on your property.
- Irrigate appropriately- Instead of several light waterings, water deeply and infrequently. A rule of thumb is usually about 1 inch of water per week, however, your arborist can advise you regarding the specific needs of your property. Ideally, watering should occur in the early mornings rather than afternoon or evenings, especially when night temperatures are still high.
- Mow adequately- Reduce mowing frequency and follow guidelines for appropriate mowing height recommended for grass species present.
Consult with your arborist for advice tailored to your property’s needs and goals, they will be able to guide you on how to prevent disease or treat effectively should it be required.
