Lesions, Spots, or Blisters
Asparagus Rust, a fungal pathogen
Asparagus rust, a fungal pathogen. Asparagus rust is characterized by light green oval lesions inearly summer followed by tan or black protruding blisters later in the season--sometimes accompanied by orange spores.
Remove volunteer asparagus near commercial fields. Plant resistant varieties such as Jersey Giant, Martha Washington, and Viking KB3. Orient rows in the direction of prevailing winds, and thin rows if necessary to facilitate air movement. Many approved fungicides are being removed from the market. Contact your local Extension Agent, or the U of M Plant Disease Clinic at: 612-625-1275 for current recommendations.
Insect Defoliation accompanied by Bent Spears
Crioceris asparagi, the common asparagus beetle
The common asparagus beetle (crioceris apraragi) is a blue-black beetle with white spots. In the larval stage, it is gray with a black head.
This insect can cause serious defoliation, sometimes weakening plants and pre-disposing them to seconday fungal pathogens. In addition eggs laid on spears can make them unappealing. The most effective treatment practice may be the removal or burning of plant residue each season to reduce overwintering sites for this pest. In addition, volunteer asparagus near managed fields should be removed.
Crioceris duodecimpunctata, the spotted asparagus beetle
The spotted asparagus beetle (crioceris duodecimpunctata) is an orange beetle with black spots; it is also orange in its larval stage.
The spotted asparagus beetle appears later in the season than the common asparagus beetle and causes little significant damage. No treatment is usually necessary. However if significant defoliation does occur, use pesticides labeled for this pest. The most effective treatment practice may be the removal or burning of plant residue each season to reduce overwintering sites for this pest. In addition, volunteer asparagus near managed fields should be removed.