Diseases of Asparagus
1.Crown Rot & Seedling Blight: Fusarium oxysporum f. sp. asparagi
Symptoms
Crown rot coupled with winter injury can reduce newly seeded and established asparagus plantings by up to 50% or more in a year. Infected seedlings will exhibit stunting, yellowing and wilting of the foliage as the primary roots are rotted off. Established plants will produce spindly spears in the spring. Shoots become dwarfed, wilted and brown in color. Later in the season one or more shoots per crown appear stunted, turn yellow, then can wilt and die. Roots are also rotted and discolored.
Management
The disease is seed- and soil-borne. New plantings should be established on soil (welldrained, sand-loam soils are preferred) where asparagus has not been previously grown for at least five years. Use strong healthy plants (1 year crowns) to start a plantation and to ensure good plant health by following good planting and growing procedures such as fertilization, insect and weed control and avoid over harvesting.
2.Purple Spot: Stemphyllium vesicarium
Symptoms
This disease can render the spears unmarketable by the presence of numerous purplish lesions or spots. The lesions are superficial, slightly sunken and purple. There can also be larger spots that are brown in the middle with a purple margin. Often these lesions will be more prevalent on one side of the spear that the other. On the asparagus fern there will be light brown lesions, up to 15mm long, with dark purple edges. In severe cases, defoliation and dieback can happen. Repeated defoliation can lead to a reduction in yield.
Management
Remove or bury crop residue in the fall to help limit infection.
3.Rust: Puccinia asparagi
Symptoms
Red or brown elongated spots appear on the shoots spears or needles of asparagus. Successive years if infestation reduces root vitality resulting in poor shoot development and death.
Management
Plant in areas with good air circulation and irrigate during the day so plants can dry out before evening.
super