Extreme Southern California weather, October, 2007.

View Larger Extreme increases in air temperature and rapid drops in relative humidity can result in severe damage to areas recently overseeded with ryegrass and Poa trivialis. The Santa Ana condition that resulted in the weather shown above is illustrated in these graphs from San Diego, CA. Warm and dry air accompanied by high winds can destroy overseeded ryegrass if irrigation is not adequate. The first 14 days after overseeding with ryegrass or Poa trivialis need to be closely monitored for abrupt changes in weather, such as those shown here.

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Cultural Practices