Plant Disease Management Handbook

Cause Globisporangium ultimum (formerly Pythium ultimum) or Rhizoctonia solani, fungus-like and fungal microorganisms that live in soil and attack seedlings of many different crops. As seedlings mature, they become resistant to attack. The disease can be a serious problem in cool, wet soils.

Cause Rhizoctonia solani, a fungus. The disease is widespread, occurring most often on muck soil. It commonly attacks 'Big Boston' types of head lettuce.

Cause This viral disease is soilborne and transmitted by the oomycete, Olpidium virulentus (formerly known as O. brassicae). Mirafiori lettuce big-vein virus (MLBVV) (formerly known as mirafiori lettuce virus) has been recently identified as a causal agent of big vein while lettuce big-vein associated virus (LBVaV) (formerly known as lettuce big-vein virus), previously thought to cause big vein, is yet to be confirmed as a causal agent.

Cause Microdochium panattonianum (formerly Marssonina panattoniana), a fungus that overwinters on crop refuse or in soil as microsclerotia, surviving in soil as long as 4 years. It also can be harbored in weed hosts such as prickly lettuce (Lactuca serriola). The disease is important only in prolonged periods of wet weather when it may cause heavy losses.

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Onion (Allium cepa) - Iris Yellow Spot

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Lawn and Turf - Downy Mildew (Yellow Tuft)

Host Bluegrass, bentgrass, and annual bluegrass have shown infections.

Host All grasses are susceptible.

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Wheat (Triticum aestivum) - Take-all

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Grass for Seed - Stripe Smut

Hosts Many, but primarily bluegrass and bentgrass.