Lawn and Garden
In order to have disease in your lawn conditions must be right for a ‘disease triangle’. The three components of a disease triangle are; pathogen, host and environment. Most lawn diseases favor cool, damp nights. As nocturnal temperatures fall you should anticipate an increase in disease occurrence. If it also rains a lot you can expect even more disease issues.One way to impede the proper environment for diseases is to not irrigate if rainfall has occurred. The growth of the lawn will begin to slow down as the days get shorter and the nights get cooler. This means the lawn requires less water. If nature is supplying ample amounts of water (about 1”/week), additional irrigation is only going to support the necessary environment for disease to thrive.In most instances the spores of a disease needs to be in direct contact with water drops for them to become active. This is why over watering supports disease activity. You want there to be enough water to meet the needs of the grass but not so much as to encourage diseases. You also do not want to extend the ‘dew point’ in your yard. The dew point is when conditions are right for dew to form. Applying water in the evening before dew forms means your lawn will be wet for an extended period of time increasing the chances for disease activity. If you do need to irrigate the lawn, do so at sunrise so the water drops on the grass will be evaporated by the rising sun. Areas in the lawn that are most likely to become diseased are ones in the shade, ones that are low or areas near sprinkler heads or down spouts. Disease outbreaks can be treated with a fungicide. Most lawn fungicides are preventative not curative. This means they need to be in place to deter new infection. Each time it rains or the irrigation system runs the fungicide can potentially be washed off and any form of control it offers is lost. Try to irrigate minimally once you employ a fungicide spray program, unless otherwise indicated on the product label.Once we get a frost, most lawn diseases will go dormant for the proper environment has passed. During winter your lawn should not experience disease issues for it is too cold. Disease will then reoccur during the cool nights of spring.