Plant Disease Management Handbook

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Wheat (Triticum aestivum) - Barley Yellow Dwarf

Cause The soilborne fungus, Cephalosporium gramineum (sexual: Hymenula cerealis), overwinters in association with infected crop residue. Plants are infected through wounds in the root system caused by cultivation (including fertilizer application), frost heaving, freeze damage without heaving, or soil insects. Because frost heaving aggravates disease development, the disease is worse on wet, poorly drained soils.

Image related to Wheat (Triticum aestivum)-Cephalosporium Stripe
Note the necrotic areas on the stems.
Photo by Paul Koepsell, 1973.

Cause Numerous species of fungi, including Alternaria alternata, Fusarium spp. including F. oxysporum, and Helminthosporium spp. Fusarium proliferatum is one species that has been reported to pathogenic to wheat if it occurs on seed.

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Grass for Seed - Barley Yellow Dwarf

Image related to Wheat (Triticum aestivum)-Barley Yellow Dwarf

Note the infected Stephens wheat plant on the left and a normal plant on the right.

Photo part of OSU Extension Plant Pathology Slide Collection

Image related to Wheat (Triticum aestivum)-Barley Yellow Dwarf
Leaf tips of affected wheat in May.
Photo by Cynthia M. Ocamb, 2009.
Image related to Wheat (Triticum aestivum)-Barley Yellow Dwarf
Leaf tips of affected wheat in June.
Photo by Cynthia M. Ocamb, 2009.

Cause The bacterium, Xanthomonas translucens pv. undulosa (formerly X. campestris pv. translucens), infects many cereals (barley, oats, rye, triticale) and grasses. Severe epidemics are periodic in irrigated wheat. The pathogen may be seedborne or persist in soil and infected plant residue. The disease can spread by water, spike-visiting insects (aphids), plant-to-plant contact, and seeds.

Symptoms on stems of Triticum durum 'Waid'.

Bob Forster collection

Slimy droplets may develop on diseased tissue in wet weather.

Bob Forster collection

Symptoms in heads consist of dark-brown, black, or purple streaks and blotches.

Bob Forster collection

Diseased heads may be sterile if infected before flowering. Triticum durum 'Waid'.

Bob Forster collection

Cause The bacterium, Pseudomonas syringae pv. syringae, causes a disease favored by cool to mild temperatures (59°F to 77°F) and high relative humidity. The bacterium is in seeds, soil, plant residues, and water and may spread by infected seed or water. Severe epidemics are periodic in irrigated wheat. Other cereals may be affected, including oats, rye, and triticale.

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Cedar, Western Red (Thuja plicata)

Cause Physiologic: any sudden change in environment or even a gradual change to below-optimum growing conditions. Cold drafts, cold water, dark location, time of year, or simply moving it to a different location in the house can cause leaves to drop. This plant needs plenty of indirect light and 60°F to 70°F temperatures.

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California Wax-myrtle (Morella californica)

Cause A virus, zucchini yellow mosaic virus (ZYMV), that is found worldwide and can cause devastating losses. Several aphid species non-persistently spread this virus; it can be spread by mechanical means. Little is known about its overwintering.

Symptoms A yellow mosaic and severe malformations, necrosis, severe stunting of size and leaf lamina, and fruit cracking. Seeds may be deformed.