Here in Northern Colorado we have been receiving a lot of rain, this should be good for your lawn, right? A significant increase in temperature, following a lot of rain in a short amount of time, is one of the factors that can trigger an outbreak of Ascochyta in Kentucky Bluegrass. Because of all of mother nature’s moisture people have turned their sprinklers off and leave them off too long, coupled with a few days of hot and dry weather conditions contributes to an Ascochyta outbreak. Ascochyta erupts very fast and it looks like the lawn is bleached or turning to straw. This is especially noticeable after mowing, sometimes leaving stripes in the turf. It resembles drought stress but the damage is usually restricted to the leaves and the crowns and roots are not killed off. The start of Ascochyta looks like the top 1/3 of the blade of grass has been bleached and appears pinched. It dies back from the tips first and spreads downward. The areas around can be all bleached and yellow in appearance. The lawn can come out it without treatment but will take 2-3 weeks or longer. In some cases, a fungicide applied by a licensed professional will help reduce Ascochyta and speed up recovery.
Some ways to reduce the risk of Ascochyta is:
- Water your lawn consistently on a schedule is extremely important. A lawn that is stressed because irrigation was off or run times too short is more prone to Ascochyta.
- Reduce thatch and encourage moisture penetration with aeration. Proper drainage is another important component in avoiding Ascochyta.
- Maintain grass height between 3-4 inches (see my post about mow height (Tall is happy and short is crappy!)
- Mowing less frequently (leaving your grass taller) and sharpening your mower blade to reduce “wounding” the grass blades.
Want more info? Check out these helpful links: http://www.ext.colostate.edu/pubs/garden/02901.html