Septoria leaf and glume blotch is caused by several species of the fungus Septoria, including S. tritici, S. nodorum, and S. avenae f. sp. tricicea. Septoria leaf blotch is economically important in most wheat-growing regions; S. tritici appears to be the most important in the High Plains. Wheat strains of Septoria spp. are also weakly virulent on barley, rye, and other grasses, especially bluegrass. The pathogen survives on crop debris, seed, and volunteer wheat, but airborne ascospores can also serve as primary inoculum.
Septoria leaf blotch symptoms can develop throughout the growing season on all above ground plant parts. Initial symptoms include chlorotic specks, usually on leaves in contact with the soil; later they expand into irregularly shaped necrotic lesions approximately 0.04 to 0.2 inches by 0.16 to 0.6 inches. Lesions tend to be restricted laterally and form parallel to each other. Lesions can also be water-soaked and later turn dry, yellow, and then red-brown. Glumes and awns can sometimes be infected. Yield losses of 10 to 20% are more common under disease favorable conditions, but yield losses in the High Plains average 2 to 6% annually.
No biological control strategies have been developed for Septoria leaf blotch.
No resistant varieties are available, but some varieties possess some level of resistance and should be planted if available. Early maturing varieties tend to be most susceptible. Plant only high-quality pathogen free seed. Bury or otherwise destroy wheat stubble and volunteers. Reduced or no-till wheat production increases Septoria leaf blotch, but longer rotations (at least two years) reduce pathogen carry-over. Discourage thick, lush canopies favorable to the disease by increasing row spacing and avoiding excess fertilization and irrigation.
Product List for Septoria Leaf Blotch:
Pesticide |
Rate per Acre |
Application Frequency |
Remarks |
|
|
Carboxin: various formulations and mixtures available |
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|
Vitavax 200 Flowable |
3-4 fl oz |
-- |
Seed treatment |
|
|
RTU-Vitavax-Extra |
5 fl oz |
-- |
Seed treatment |
|
|
RTU-Vitavax-Thiram |
5-6.8 fl oz |
-- |
Seed treatment |
|
|
Vitavax-PCNB flowable |
5-7 fl oz |
-- |
Seed treatment |
|
|
Vitavax-Thiram-Lindane |
5 fl oz |
-- |
Seed treatment |
|
|
Copper fungicides: not all formulations listed |
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|
Champ DP |
1.0-1.33 lb |
10 days, beginning early heading |
Seed treatment |
|
|
Cuprofix Disperss |
2.0-2.5 lb |
10 days, beginning early heading |
Seed treatment |
|
|
Kocide 101 |
1.5-2.0 lb |
10 days, beginning early heading |
Seed treatment |
|
|
Nordox |
1.5-2.0 lb |
10 days, beginning early heading |
Seed treatment |
|
|
Nu Cop 50 WP |
1.5-2.0 lb |
10 days, beginning early heading |
Seed treatment |
|
|
Copper/EBDC |
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Cuprofix MZ Disperss |
2.5-4.75 lb |
10 days, beginning early heading |
Maximum of 15.7 pounds per season; 26 day PHI; grazing restrictions |
|
|
ManKocide |
2.0-2.5 lb |
10 days, beginning early heading |
Maximum of 32 pounds per season; 26 day PHI; grazing restrictions |
|
|
Difenoconazole |
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|
Dividend Extreme |
1-4 fl oz |
-- |
Seed treatment; 55 day PHI |
|
|
Dividend |
0.5-1 fl oz |
-- |
Seed treatment; 55 day PHI |
|
|
EBDC: not all formulations listed |
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|
Dithane DF |
2.1 lb |
7-10 days; beginning early heading |
Maximum of 3 applications; Performance improved by addition of non-ionic surfactant; 26 day PHI; grazing restrictions |
|
|
Manzate 75DF |
2 lb |
7-10 days; beginning early heading |
Maximum of 3 applications; 26 day PHI; grazing restrictions |
|
|
Penncozeb 75DF |
1.0-2.0 lb |
7-10 days; beginning early heading |
Maximum of 3 applications; 26 day PHI; grazing restrictions |
|
|
Propiconazole |
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|
PropiMax EC |
4 fl oz |
1 spray at Feeks 8 |
40 day PHI |
|
|
Tilt 3.6E |
2-4 fl oz |
1 spray at Feeks 8 |
40 day PHI |
|
|
Strobilurin and Strobilurin/Propiconazole |
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|
Headline |
6-9 fl oz |
10-14 days, begin at Feeks 10.3-10.5 |
Maximum of 2 applications; 14 day PHI |
|
|
Quadris |
6.2-15.3 fl oz |
10-14 days, begin at Feeks 10.3-10.5 |
Maximum of 2 applications; 45 day PHI |
|
|
Stratego |
10 fl oz |
10-14 days, begin at Feeks 8 |
Maximum of 2 applications; 35 day PHI |
|
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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. |
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Categories: Small Grains, Disease, Septoria Leaf Blotch
Date: 3/9/2005