Halo Bacterial Blight Control – Treating Halo Blight In Oats

Halo Bacterial Blight Control – Treating Halo Blight In Oats

By: Amy Grant

Halo blight in oats (Pseudomonascoronafaciens) is a common, but nonlethal, bacterial disease that afflictsoats. Even though it is less likely to cause significant loss, halo bacterialblight control is an important factor to the overall health of the crop. Thefollowing oats halo blight info discusses the symptoms of oats with halo blightand management of the disease.

Symptoms of Oats with Halo Blight

Halo blight in oats presents as small, buff colored, water-soakedlesions. These lesions usually occur just on foliage, but the disease can alsoinfect the leaf sheaths and chaff. As the disease progresses, the lesionsexpand and coalesce into blotches or streaks with a characteristic pale greenor yellow halo surrounding the brown lesion.

Halo Bacterial Blight Control

Although the disease is not fatal to the overall oatcrop, heavy infections do kill off the leaves. The bacterium entersthe leaf tissue through the stoma or through insect injury.

The blight is fostered by wet weather and survives on cropdetritus, volunteer grain plants and wild grasses, in soil, and on grain seed.Wind and rain spread the bacteria from plant to plant and to different parts ofthe same plant.

To manage oat halo blight, use only clean, disease freeseed, practice crop rotation, remove any crop detritus, and, if possible, avoidthe use of overhead irrigation. Also, manage insect pests since insect damageopens the plants up to bacterial infections.

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Biology

Hail, blowing sand or wind-whipping, followed by rain, often trigger bacterial blights. Bacterial blights are also spread if bean rows are cultivated while leaves are wet. The most common bacterial diseases are halo blight and common blight (aka bacterial brown spot).

Halo blight may occur any time during the cropping season. Typical symptoms are small brown spots that are surrounded by a light-green or yellow halo. The halo ranges from dime-size to the size of a quarter. It is caused by a toxin produced by the halo blight bacterium when the temperatures are less than 21ºC(70ºF) for at least part of the day. In hot weather, halo blight will resemble bacterial brown spot.

Both diseases are carried on the seed and can be spread from plant to plant by rain, hail, irrigation, or wind. In the soil, blight can survive in old, diseased plants for a year or longer.


Outback Forage Oats

Outback oats are derived from South African, Australian and North American hay and grazing oat germplasm. Outback is selected for adaptation to the Australian agricultural environment. Outback is primarily a forage oat, developed to produce a large bulk of quality forage in autumn and again in spring. Outback is a mid to late maturing oat with distinctive dark green and broad leaves. Outback oats provide higher yields of quality grazing throughout the critical autumn, winter and early spring grazing periods.

  • Medium height, erect specialist hay and grazing oat
  • Mid – late maturity
  • High forage quality and total yield
  • Dark green broad leaves
  • More rapid establishment, shows excellent seedling vigour
  • Better moisture stress tolerance
  • Ideal for oaten hay production and grazing
  • Suited to a wider range of soils
  • Excellent frost resistance
  • Fantastic late sown option to provide high quality feed


Insect/Mite Pests

Disease: Seedcorn maggot
Pathogen: Delia platura
Host Crops: Many vegetable crops including snap, kidney, and lima beans, onion, corn, turnip, pea, cabbage, and cucurbits. They cause the most damage in spring to newly emerging seedlings.

On-Line Resources:

Seed Corn Maggot. VegEdge, University of Minnesota

Common name: Spider mites
Latin binomial: Tetranychus spp. including two-spotted spider mite (Tetranychus urticae), strawberry spider mite (Tetranychus turkestani), and Pacific spider mite (Tetranychus pacificus)
Host crops: Wide host range, including many vegetables such as bean, carrot, potato, etc.

Online Resources:

Common name (of damaging stage): Wireworm (adults are called click beetles or snapping beetles)
Latin binomial: Ctenicera spp. and Limonius spp. Several kinds of wireworms are in the Pacific Northwest. Wireworms causing the most damage in irrigated areas are the Pacific Coast wireworm (Limonius canus), the sugar beet wireworm (L. californicus), the western field wireworm (L. infuscatus), and the Columbia Basin wireworm (L. subauratus). The Pacific Coast and sugar beet wireworms are the most common. Where annual rainfall is

On-Line Resources:

Managing Wireworms in Vegetable Crops. Ontario Ministry of Agriculture and Food

Wireworms. VegEdge, University of Minnesota.

Dry beans: Wireworms. UC IPM Online, University of California

Wireworm Field Guide – A guide to the identification and control of wireworms, Syngenta Crop Protection Canada, Inc.


Elliott was born in Berlin, Wisconsin. She got her undergraduate degree in zoology at Stanford University in 1907. For a few years afterwards she taught biology at the state normal school in Spearfish and took summer courses at the University of Chicago. [3] [4] She returned to Stanford for master's work in plant physiology, receiving her A.M. in 1913. [1] She was offered an appointment as assistant in the botany department but refused for reasons having to do with her family and instead returned to Wisconsin. [3]

In Wisconsin, she worked for two years (1914–16) as an instructor at South Dakota State College of Agriculture and Mechanic Arts. [3] [4] She left to pursue graduate work in plant pathology, first as a research assistant at the Brooklyn Botanic Garden and then as a Ph.D. student at the University of Wisconsin, Madison, where she was supported by a Boston Alumne Fellowship. [3] [4] In 1918, she became the first woman to complete the doctoral program in botany at the University of Wisconsin, Madison. [1] Her thesis work focused on halo blight, a disease affecting oats. [1]

Elliott was recruited by the bacteriologist Erwin Frink Smith to work in the Bureau of Plant Industry at the United States Department of Agriculture (USDA). [1] There she continued her research as a phytobacteriologist or specialist in the organisms harmful to plants, publishing numerous papers in her field. [1] [2] Among her scientifically notable papers is one establishing the role of the flea beetle as a vector in the development of the disease known as Stewart's Wilt in corn (maize). [1] This research led to a method for forecasting how bad the disease would be in any given year based on temperature indexes that reflected how successfully the beetles had survived the preceding winter. [1] Her work also led to the description of several new species. [2]

Elliott wrote a widely used book, Manual of Bacterial Plant Pathogens, first published in 1930, reissued with revisions in 1951, and still being drawn on by researchers today. [1] [2] [5]

In 1942, she served as the president of the Botanical Society of Washington. [6]


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