Plant Disease Management Handbook

By C. M. Ocamb

Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-White Leaf Spot and Gray Stem

A pak choi leaf with white leaf spot.

Cynthia M. Ocamb, 2014.
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-White Leaf Spot and Gray Stem

A canola leaf with white leaf spot.

Cynthia M. Ocamb, 2014.
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-White Leaf Spot and Gray Stem

A close-up of white leaf spot.

Cynthia M. Ocamb, 2014.
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-White Leaf Spot and Gray Stem

Gray stem of turnip.

Cynthia M. Ocamb, 2014.

By C. M. Ocamb

Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Sclerotinia Stem Rot

Brassica plants with Sclerotinia stem rot.

Cynthia M. Ocamb, 2009.
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Sclerotinia Stem Rot

Brassica plants with Sclerotinia stem rot, note that sclerotia are forming (white-colored) or have formed (black-colored) on the outside of the canola stem.

Cynthia M. Ocamb, 2009.
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Sclerotinia Stem Rot

Brassica plant with Sclerotinia infection on top of plant.

Cynthia M. Ocamb, Feb. 2015.

By C. M. Ocamb

Cause A fungus, Cladosporium variable. This fungus can grow under a wide range of temperatures, but 59°F to 68°F with relative humidity above 80% is most conducive to disease development in seed-crop crucifers. Spores can be moved by air, rain splash, or equipment.

By C. M. Ocamb

Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Light Leaf Spot

Light leaf spot on turnip.

Cynthia M. Ocamb, 2014.
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Light Leaf Spot

Closer view of light leaf spot.

Cynthia M. Ocamb, 2014.
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Light Leaf Spot

A stem of mizuna infected with Cylindrosporium concentricum.

Cynthia M. Ocamb, 2014.

Cause Xanthomonas campestris pv. campestris is a bacterium that overwinters in plant refuse for up to 2 years and is carried internally and externally on seed. The bacterium infects other crucifer crops and weeds. It may be spread in the field by water (rain, irrigation), insects, equipment, and animals. Many outbreaks can be attributed to disease spread in the seedbed.

By C. M. Ocamb

Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Black Leg

A young Brassica seedling with a leaf spot on a cotyledon incited by Leptosphaeria maculans.

Cynthia M. Ocamb, Oct. 2014
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Black Leg

Leaf spots of Phoma lingam on turnip.

Cynthia M. Ocamb, 2014
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Black Leg

Leaf spot incited by Phoma lingam.  The small black dots are pycnidia, which produce rain-splashed spores.

Cynthia M. Ocamb, 2014
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Black Leg

A stem canker on a Brassica stem; note the tiny, black pycnidia.

Cynthia M. Ocamb, Feb. 2015
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Black Leg

Phoma lingam causing a lesion at the base of a kale stem.  Note the tiny, black pycnidia.

Cynthia M. Ocamb, Jan. 2015
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Black Leg

Stem cankers on a Brassica stem; note the tiny, black pycnidia.

Cynthia M. Ocamb, May 2014
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Black Leg

Black leg stem canker on a kale stem.

Cynthia M. Ocamb, 2014
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Black Leg

Pycnidia of Phoma lingam on kale exuding a characteristic pinkish-purplish ooze of pycnidiospores.

Cynthia M. Ocamb, 2014
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Black Leg

Close-up of Brassica crop residue colonized by Phoma lingam and Leptosphaeria maculans.

Cynthia M. Ocamb, October, 2014
Image related to Seed Crop, Crucifers (Brassica and Raphanus spp.)-Black Leg

Asci containing ascospores from a  pseudothecium.

Cynthia M. Ocamb, 2014

By C. M. Ocamb

Cabbage grown for seed with dark lesions due to abundance of dark spores.

Photo by Cynthia M. Ocamb, Oregon State University, 2011.

Cabbage seed pods atop leaf show "tiger-striping" that is characteristic of infections on seed pods.

Photo by Cynthia M. Ocamb, Oregon State University, 2011.

Spores of Alternaria on cabbage.

Photo by Cynthia M. Ocamb, Oregon State University, 2011.

See:

Greenhouse Plants, Ornamental - Pythium Seed Rot, Damping-off, and Root Rot

Rotted root due to Pythium sp.

OSU Plant Clinic image, 2011.

Root discoloration due to both Pythium and Phytophthora.

OSU Plant Clinic Image, 2011.

Fusarium sp. has also been found as a root and crown rot of Sedum.

OSU Plant Clinic, 2020.

See:

Greenhouse Plants, Ornamental - Gray Mold