Plant Disease Management Handbook

See:

Pear (Pyrus spp.) - Pacific Coast Pear Rust

Cedar, Incense - Broom Rust

Flowers and fruit can be infected early since trees are susceptible starting at bud break.

Jay W. Pscheidt, 2012.

Fruit are often deformed and enlarged with yellow to orange aecia.

Jay W. Pscheidt, 2006.

Amelanchier canadensis is very susceptible often with bright orange pustules on leaves and fruit in the spring.

Jay W. Pscheidt, 2010.

Stem can also be infected becoming swollen, deformed and bright orange with aecia.

Jay W. Pscheidt, 2006.

Stems of Amelanchier canadensis can become contorted in the spring (left) but then are girdled by mid-summer with distal portions of the branch dying back (right).

Jay W. Pscheidt, 2006.

These rust need two hosts to complete their life cycle, a conifer like the Incense cedar to the left and a Rosaceous host like the pears to the right.

Jay W. Pscheidt, 2008.

Spermagonia on the top side of the leaf and aecia on the underside of the leaf.

Photo by Jay Pscheidt, 1992.

Image related to Serviceberry (Amelanchier spp.)-Rust

Another species of Gymnosporangium (possibly nelsonii) on serviceberry.

Bob Ross, 2006.

Cause The OSU Plant Clinic has found Fusarium sp. on dusty miller Jacobaea maritima, formerly Senecio cineraria). It survives in the soil as thick-walled, dormant chlamydospores, which germinate in response to exudates from nearby plant roots. Hyphae then penetrate the roots, colonize the cortex and move into the xylem tissue. Small spores (microconidia) are produced and carried up into the plant.

See:

Vegetable Seed Treatment

Barley, Oat, Rye, Triticale, and Wheat Seed Treatments

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.

A canola leaf with white leaf spot.

Cynthia M. Ocamb, 2014.

A close-up of white leaf spot.

Cynthia M. Ocamb, 2014.

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.

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.

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.

Closer view of light leaf spot.

Cynthia M. Ocamb, 2014.

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