Powdery mildews of canola and mustard are caused by the fungi Erysiphe polygoni and E. cruciferarum. The disease cycle is initiated by windblown conidia, which infect its hosts over a range of humidity (50 to 95%) during moderate to warm (68 to 80ºF) temperatures. The pathogens overwinter as cleistothecia (sexual fruiting structures) or mycelia in volunteer host plants.
Powdery white spots appear first on leaves, and eventually grow to cover entire leaves. Symptoms usually develop on the bottom surface of older leaves first, but all leaves become diseased as plants age. Infected leaves wither and die, leading to premature defoliation. Powdery mildew reduces yield by reducing the effective photosynthetic area, but powdery mildew is not generally considered a serious disease problem on canola or mustard.
Resistant canola and mustard varieties are available and should be planted if suitable for your marketing and production needs. Eliminate volunteer host plants and crop debris.
Chemical controls must be used in combination with cultural controls to be most effective. Resistance to several fungicides has been reported in the powdery mildew fungi, so fungicides with different modes of action must be rotated or tank-mixed to prevent or delay resistance development. Thorough coverage is essential for effective disease control.>
Product List for Powdery Mildew:
Pesticide |
Product per acre |
Application Frequency
|
Remarks |
Azoxystrobin |
|||
|
Quadris |
6.2-15.4 fl oz |
7-14 days |
Maximum of 3 applications or 2.88 quarts per season; Do not make more than 1 application of Quadris before rotating to a fungicide with a different mode of action; 0 day PHI |
Neem |
|||
|
Trilogy |
1% solution |
7-14 days |
Apply in 25 to 200 gallons |
|
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, Powdery Mildew
Date: 12/31/04