Plant Pathology Part 2

Front 1

Bean root rot

Back 1

Fusarium solani f. Sp. Phaseoli. Overwinter as chlamydospores in soil. Facultative parasite. Reddish brown steaks on taproot and hypocotyl.

Front 2

Clubroot

Back 2

Plasmidiophora brassicae. A protoctistan endoparasitic slime mold.

Front 3

Eyespot of wheat

Back 3

Tapesia yallundae, foot rot fungus

Front 4

Take all of wheat

Back 4

Gaeumannomyces graminis

Front 5

Aphanomyces

Back 5

Root rot of peas and sugar beets. Oomycete.

Front 6

Phytophthora and pythium

Back 6

Oomycete, stramenopiles for root rots of many crops

Front 7

Vascular wilt diseases

Back 7

Most reside in xylem (water conducting). Crop loss is a result of blockage of the vascular tissues. Symptoms include wilting, chlorosis, necrosis and can be unilateral.

Front 8

Flagging

Back 8

When a pathogen infects one part of the root system and symptoms appear unilateral.

Front 9

Tylose

Back 9

Plant produced balloon like out growths of parenchyma cells into the lumen of adjacent xylem vessels, to prevent spread of pathogen

Front 10

Ophiostoma ulmi

Back 10

Dutch elm disease, vascular disease

Front 11

Verticillium dahliae

Back 11

Strawberry and potato vascular wilt.

Front 12

Fusarium oxysporum

Back 12

Vascular wilt disease affects many crops. Survive as macro conidia or chlamydospores in soil. Penetrates through root wounds.

Front 13

Bacterial vascular wilt pathogens

Back 13

Ralstonia solanacearum southern bacterial wilt. Erwinia tracheiphila bacterial wilt of cucurbits. Clavibacter m. Of ring spot of potato.

Front 14

Bordeaux mixture

Back 14

Copper sulfate and hydrated lime to control Downy mildew, plasmopara viticola, on grapes.

Front 15

Benzimidazole

Back 15

Fungicide class that includes benomyl and thiabendazole disrupts mitosis and meiosis.

Front 16

Smuts

Back 16

Black, dusty spore masses called sori. Produce teliospores and basidiospores and h-cells. Can be floral infecting, seedling infecting, or local infecting.

Front 17

Loose smut of wheat and barley

Back 17

Ustilaginomycetes tritici and ustilago nuda

Front 18

Use seed treatments for Smuts

Back 18

Carboxin, difenoconazole, or hot water treatments

Front 19

Common bunt of wheat

Back 19

Tilletia tritici, seedling infecting Smuts, aka stinking smut. Have h-cells.

Front 20

Corn smut

Back 20

Ustilago maydis, local infecting smut. Form galls

Front 21

Ergot

Back 21

Claviceps purpurea. Sordariomycetes. Replaces ovary with sclerotium. Conidia produced in sticky honey dew. Require free water. Control with clean seed, deep plowing, crop rotations.