alternatives to pesticides - plant disease - rust
Rust is a fungus with orange to brownish pustules on the underside and pale yellow spots on the tops of grass blades, snapdragon or hollyhock leaves, raspberries and rose bushes. It is common on Kentucky bluegrass and on the weed annual bluegrass.
Pick off and destroy affected leaves as soon as they are noticed. Leaves must be wet for four hours to become infected, so careful watering can help prevent it. Mow the lawn shorter to improve air circulation and apply a nitrogen predominant fertilizer that contains sulfur. Choose a grass seed mixture containing fine fescues and perennial rye grass, two species that are less susceptible to rust.
Least-toxic chemical control
Periodic dustings of sulfur have been found to be somewhat effective, but you should not need this unless preventive measures have failed. Sulfur can be highly irritating to the respiratory system. Wear nose and mouth protection when applying.