Canola and Mustard

 

Xanthomonas Leaf Spot

 

Howard F. Schwartz and David H. Gent

 

Identification and Life Cycle

Xanthomonas leaf spot is caused by the bacterium Xanthomonas campestris pv. armoraciae.  Little is known about the disease cycle, but other plant pathogenic xanthomonads are known to be disseminated by splashing rain and irrigation water, workers, equipment, and aerosols.  Xanthomonads tend to survive poorly in soil, and are usually found in association with infested crop debris, contaminated seed, and weed hosts.    

Plant Response and Damage

Xanthomonas leaf spot causes light brown spots on foliage, and apparently reduces the photosynthetic area of infected plants.  The disease appears to be of little concern. 

Management Approaches

 

Biological Control

No biological control strategies have been developed for Xanthomonas leaf spot.

Cultural Control

No cultural controls have been reported for Xanthomonas leaf spot.  However, management strategies common for other diseases caused by xanthomonads include crop rotation to non-hosts, thorough incorporation of plant debris, weed control in and around fields, and furrow irrigation from pathogen-free sources of water such as wells. 

Chemical Control

Copper bactericides may provide some Xanthomonas leaf spot suppression if applied preventatively and regularly.

Product List for Xanthomonas Leaf Spot:

Pesticide

Rate per Acre

Application Frequency

Remarks

Copper fungicides: not all formulations listed

Champ DP

0.33-0.66 lb

 7 days

 

Cuprofix Disperss

1.5-2.5 lb

7-10 days

Can cause phytotoxicity

Kocide 2000

0.75-1.5 lbs

7-10 days

 

Nordox

1.0-3.0 lb

7-10 days

 

Nu Cop 50 WP

1.5-2.0 lb

7-10 days

 

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.

 

 

Categories: Canola and Mustard, Disease, Xanthomonas Leaf Spot

Date: 12/30/2004