History: Stripe rust was first described in Europe in 1777. First reports in the United States date from the early 20th century. Historically it has been a problem in the Pacific Northwest, California and the higher mountain valleys. Yield losses of up to 25% have been reported from Washington State. Over the last few years, stripe rust has become increasingly important in the Great Plains, particularly the south-central states. This is probably due to the development of new strains which tolerate a much broader range of temperatures, and infect a broader range of wheat varieties.
Causal agent: Puccinia striiformis f. sp. tritici. P. striiformis f. sp. tritici is a pathogen of wheat, but can infect some susceptible barley varieties. Stripe rust of barley is caused by a different subspecies, Puccinia striiformis f. sp. hordei. As with other cereal rusts, physiological races of this pathogen that are able to infect different varieties of wheat (sometimes called strains) are common.
Symptoms: Stripe rust is characterized by bright yellow-orange pustules arranged between the veins in stripes. In Europe and many parts of the world, stripe rust is known as ‘yellow rust’ because of the distinctive coloring of the pustules. Stripes are not formed on seedling leaves. Atypical symptoms for stripe rust, including yellow spotting, can occur on varieties with resistance to some strains.
Occurrence: Whenever there is green plant tissue. Stripe rust is considered a cool season disease, and is most severe in spring and early summer (May to July). This disease usually appears earlier in the season than other rusts because it can develop at cooler temperatures. Dark-brown to black teliospores (sexual spores) will appear as the plant matures and the temperatures rise. Stripe rust does not have a known alternate host. Perennial grasses can serve as an important reservoir of inoculum.
Life cycle of the pathogen: Stripe rust survives in green tissue, and in colder climates has been known to survive as dormant mycelium under snow cover. It travels by wind from neighboring wheat-growing regions, but can also overwinter on wheat and perennial grassy weeds. The pathogen is favored by cool, wet conditions. Several asexual disease cycles can occur in a single season.
In Montana, winter wheat is usually more severely affected by stripe rust since the pathogen can overwinter and increase early on the crop. Depending on temperature and moisture, stripe rust can move into spring wheat and cause appreciable damage.
In South Dakota, stripe rust does not appear until the winter wheat is far enough along that losses are minimal. In contrast, stripe rust has been an issue in spring wheat during cool summers.
· Plant varieties with at least a moderate level of resistance. Check your local variety recommendations.
· Eliminate grassy weeds and volunteer wheat at least 3 weeks before planting to prevent a ‘green bridge’ for movement of the pathogen.
· Scout winter wheat in the fall and spring for stripe rust.
· Examine the fence rows, ditch banks, and other areas with perennial grasses for stripe rust. Perennial grasses such as Bromus spp. often stay green longer than the cultivated crop and may play an important role in the ‘green bridge.’
· Delay planting of winter wheat (to avoid the ‘green bridge’).
Apply a fungicide based on the following criteria:
· Rust on lower leaves (early rust increases potential yield loss)
· Presence of rust locally on wheat
· Susceptibility of varieties being grown
· Current and 30-day weather forecasts for mid-May to mid-June (cool, wet weather favors rust)
· Irrigated or dryland wheat (irrigated wheat is more at risk)
· Potential yield of crop should be at least 45 bu/a dryland and 75 bu/a irrigated. Alternatively, one needs a 4-5 bu yield increase to pay for the fungicide application
· Keep the flag and flag-1 leaves free of infection since they contribute significantly to yield
· Most products have a preharvest interval; check the label
· Quilt has proven the most effective in Montana; Tilt is marginally effective; contact fungicides such as Bravo are not effective because they do not protect the plant from subsequent infection cycles
Product list for Stripe, Leaf and Stem Rust, and other Leafspot Diseases:
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Product2 |
Mode of action |
Target diseases |
Product rate/acre |
Application timing |
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Quilt (Syngenta) |
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Leaf rust Stem rust Stripe rust Tan spot Septoria glume blotch Septoria leaf blotch Powdery mildew Spot blotch Helminthosporium |
7-14 fl oz |
Up to Feekes 9 (ligule of flag leaf just visible) |
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Headline |
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Leaf rust Stem rust Stripe rust Tan spot Septoria leaf spot Septoria glume blotch Powdery mildew Spot blotch |
6-9 fl oz |
Up to Feekes 10.5 (late heading emergence) plant stage |
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Quadris (Syngenta) |
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Leaf rust Stripe rust Stem rust Septoria leaf blotch Septoria glume blotch Tan spot Powdery mildew |
6.2-10.8 fl oz |
Feekes 6 (immediately after jointing) to 10.5 (late head emergence) |
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Stratego (Bayer) |
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Leaf rust Stripe rust Stem rust Septoria leaf blotch Tan spot Powdery mildew |
10 oz |
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Tilt (Syngenta) |
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Leaf rust Stripe rust Stem rust Septoria leaf spot Septoria glume blotch Tan spot Powdery mildew |
4.0 fl oz |
Feekes 8 (emerging flag leaf) |
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(Dow AgroSciences) |
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Leaf rust Stripe rust Stem rust Septoria leaf spot Septoria glume blotch Tan spot Powdery mildew |
4.0 fl oz |
Feekes 8 (emerging flag leaf) |
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Manzate 75DF |
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Leaf rust Septoria glume blotch Septoria leaf spot Tan spot |
2.0 lb |
Feekes 10 (boot) and again at 10.5 (late head emergence) |
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Dithane DF F-45 M-45 (Dow AgroSciences) |
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Leaf rust Septoria glume blotch Septoria leaf spot Tan spot |
2.1 lb 1.6 qts 2.0 lb |
Feekes 10 (boot) and again at 10.5 (late head emergence) |
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Penncozeb 80WP 75DF (Elf Atochem) |
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Leaf rust Septoria glume blotch Septoria leaf spot Tan spot |
1.0-2.0 lb |
Feekes 10 (boot) and again at 10.5 (late head emergence) |
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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, Diseases, Stripe Rust
Date: 2/6/08
