asparagus rust

Symptoms

Bright orange-red pustules on ferny summer growth + bushy stems, severe infection causes premature fern death + yellowing, weakened crowns produce thin + low-yielding spears the following spring, dark teliospores form on dying stems in autumn.

Plants affected

• asparagus

Easily confused with

• Fusarium crown + root rot of asparagus

  How to tell them apart: Puccinia asparagi (asparagus rust) shows its signature ON the green fern: raised, powdery pustules erupting through the cladophyll and stem surface — bright orange-yellow in early/mid season, turning rusty cinnamon-brown, then black overwintering pustules in autumn; rub a stem and orange spore dust comes off on your finger, and the yellowing fans outward from these spots. Fusarium oxysporum f.sp. asparagi (Fusarium wilt/crown rot) has NO surface pustules and nothing rubs off: instead spears emerge few and spindly, ferns yellow and wilt one-sided or whole-plant from the base upward, and the diagnosis is made by cutting the crown and lower stem lengthwise to reveal red-brown to chocolate streaking of the internal vascular tissue plus rotting, reddish roots. Rust = colourful dust on intact green tissue; Fusarium = clean exterior but brown rot inside the crown when you cut it open.

• asparagus beetle

  How to tell them apart: Both leave asparagus fern yellowing and browning in summer, but look closely at the foliage surface. Asparagus beetle (Crioceris asparagi) shows the cause physically present: 6-8 mm blue-black beetles with creamy-yellow squares and red margins, slug-like grey-green larvae on the stems, rows of dark upright eggs glued to spears and fronds, and chewed, stripped, ragged cladophylls. Asparagus rust (Puccinia asparagi) leaves the foliage intact but blistered: raised powdery pustules that rub off as orange-rust dust in summer, turning to brick-red then black crusty streaks along the stems in autumn, with no insects and no chewing. If you see beetles, larvae or egg rows it is the beetle; if you see powdery orange-to-black pustules on otherwise uneaten stems it is rust.

Common questions

How do I recognise asparagus rust on asparagus?

Bright orange-red pustules on ferny summer growth + bushy stems, severe infection causes premature fern death + yellowing, weakened crowns produce thin + low-yielding spears the following spring, dark teliospores form on dying stems in autumn.

Do I have to report asparagus rust?

No. asparagus rust is not a notifiable organism, so there is nothing to report to an authority. Treat it as a normal garden problem.

How is asparagus rust treated?

Mainly with biological and cultural measures — removing affected material, changing the conditions that favour it, and treating with agents approved in your country. The exact steps and their timing depend on the plant, the season and where you live: Dr. Phyto works them out in a free diagnosis.