UC IPM Online UC ANR home page UC IPM home page

UC IPM Home

Search

SKIP navigation
How to Manage Pests

Home & garden
Agriculture
Natural environments
Exotic & invasive

Weather data & products
Degree-days
Interactive tools & models

Identification Galleries

Natural enemies
Weeds

Educational Resources

Publications & more
Workshops and events
Training programs
Pesticide information

Research and IPM

Grants programs
Funded-project results

 
  Printer-friendly version

How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Cole Crops

White Rust

Pathogen: Albugo candida

(Reviewed 6/07, updated 11/08)

In this Guideline:

SYMPTOMS

The fungus infects leaves and floral parts, causing distinctive white, raised pustules to form underneath the plant epidermis. These blisterlike pustules sometimes result in twisted, deformed growth of the stem, leaves, or flowers. When mature, the epidermis covering the pustule will rupture, releasing powdery white sporangia (a type of spore) that can be carried by winds or splashing water onto neighboring host plants. Severely infected leaves can wither and die.

COMMENTS ON THE DISEASE

The white rust pathogen of crucifers infects only plants in this host group, including arugula, bok choy, broccoli raab (rappini), Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, Japanese or Mizuna-type mustards, radish, tah tsai, and turnip. However, economic damage is only found on the crucifer crops in which the leaves are marketed. If free moisture and cool temperatures are present, the sporangia germinate by producing several smaller motile spores (zoospores) that swim and enter susceptible young tissues. Because A. candida is dependent on cool, wet conditions, the disease is consistently more severe during winter and early spring months. In addition to sporangia, A. candida also produces a second type of spore, the oospore, that can resist drying conditions and enable the fungus to survive in a dormant state in soil or crop residue. The white rust pathogen exists in the form of distinct races.

MANAGEMENT

White rust resistant cultivars do not appear to be available for the host plants grown in California. Reducing leaf moisture by avoiding sprinkler irrigation will not prevent white rust, but keeping leaves dry may reduce disease severity. For sensitive crops such as arugula and rappini, avoid planting in fields having a history of white rust problems; soilborne oospores may result in severe disease. Fungicides may be appropriate in some situations on leafy crucifer crops. The same fungicides that control downy mildews are also effective against white rust.

Common name Amount/Acre R.E.I.+ P.H.I.+
(trade name)   (hours) (days)
The following materials are listed in order of usefulness in an IPM Program. Also, consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. MEFENOXAM
  (Ridomil Gold) EC 1–2 pt 48 0
  MODE OF ACTION GROUP NAME (NUMBER1): Phenylamide (4)
  COMMENTS: Apply as a soil application at planting; can be preplant incorporated or applied as a soil surface spray after planting.
 
B. MEFENOXAM/CHLOROTHALONIL
  (Ridomil Gold/Bravo) 76.5 1.5 lb 48 7
  MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M5) and phenylamide (4)
 
C. FOSETYL-ALUMINUM
  (Aliette) Label rates 12 3
  MODE OF ACTION GROUP NAME (NUMBER1): Phosphonate (33)
  COMMENTS: Do not tank mix with copper compounds.
 
D. COPPER# Label rates see label 0
  MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M1)
  COMMENTS: Not all copper compounds are approved for use in organic production; be sure to check individual products.
 
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
# Acceptable for organically grown produce.
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. For fungicides with mode of action Group numbers 1, 4, 9, 11, or 17, make no more than one application before rotating to a fungicide with a different mode of action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action Group number.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Cole Crops
UC ANR Publication 3442
Diseases
S. T. Koike, UC Cooperative Extension, Monterey County
K. V. Subbarao, Plant Pathology,UC Davis, Salinas

Top of page

Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2009 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See How to manage pests, or in the U.S., contact your local Cooperative Extension office for assistance. /PMG/r108101411.html revised: September 23, 2009. Contact webmaster.