Plant Disease Management Handbook

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Notes Some products are registered for lily and not tulip such as the following:

Cannonball WG at 7 oz/A applied at planting. Group 12 fungicide. 12-hr reentry.

Cause Botrytis elliptica and B. cinerea, fungi. The former has been reported on crocus, daylily, and gladiolus but is primarily on lily while the latter has a huge host range. Botrytis overwinters as sclerotia in the debris of plant shoots that mature and decay in fall. In spring, sclerotia on or near the soil surface produce conidia that infect leaves. Conidia are windblown to healthy foliage.

Image related to Lily (Lilium spp.)-Botrytis Blight (Fire)

Necrotic leaves and leaf spots due to Botrytis.

OSU Plant Clinic Image, 2014.

Although copper-based products are helpful they will not remove leaf spots.

OSU Plant Clinic Image, 2014.

Black sclerotia of Botrytis have developed on this leaf and serve as a survival structure for the fungus.

OSU Plant Clinic Image, 2014.

Note the necrotic blotches on the leaves.

Photo by Jay W. Pscheidt, 1990.

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Lily (Lilium spp.) - Root Rots

This bulb had many different fungi in addition to Fusarium and bulb mites.

OSU Plant Clinic image, 2020.

Cross section through the bulb from above image.

OSU Plant Clinic image, 2020.

Cause There are several organisms that have been associated with root rots of lilac including Phytophthora, Rhizoctonia and Armillaria. These diseases are generally found where plants are in cold wet soils and/or overwatered. Young, nursery-grown plants can get root rot as well as mature bushes grown in landscapes.

Image related to Lilac (Syringa spp.)-Root Rot

Plants in pots can also get Phytophthora root rot.

Jay W, Pscheidt, 2006.

Lilac root rot where both Phytophthora sp. and Pythium sp. were found. Cut midway shows transition from healthy vascular system above to discolored tissue below.

OSU Plant Clinic, 2021.

Young plants are as susceptible as older ones to Phytophthora root rot.

Jay W, Pscheidt.

Lilac with Phytophthora crown and root rot. Note dead branches in the middle of the bush.

Jay W. Pscheidt, 2006.

Cause The fungus Erysiphe syringae (formerly Microsphaera syringae) is found generally and can also infect Privet (Ligustrum spp.). Phyllactinia syringae has been reported from Idaho and E. penicillata has been reported from WA. Cultivars of S.

Note the white patches on the leaves.

Jay W. Pscheidt, 2020.

Colonies can cover the leaves.

Jay W. Pscheidt, 2020.

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Crabapple (Malus spp.) - Stem Rot

Phytophthora sp. was isolated from the discolored canker on this sample.

OSU Plant Clinic, 2021.

Cause Several fungi have been reported from the Pacific Northwest including Alternaria sp. (leaf spot), Ascochyta syringae (leaf blight), and Phyllosticta sp. (leaf spot). Airborne or water-splashed spores infect young leaves during wet weather, in the spring.

Symptoms Light-brown to dark-brown necrotic leaf spots and blights.

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Maple (Acer spp.) - Leaf Scorch

Image related to Lilac (Syringa spp.)-Leaf Scorch

This plant suddenly scorched after after a small amount of rain. This was the first rain since fertilizer has been applied too heavily to the base of the bush.

Jay W. Pscheidt, 2007.

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Hydrangea - Bud and Flower Blight

Image related to Lilac (Syringa spp.)-Gray Mold

Flowers are turning water soaked, brown and the fuzzy sporulation of Botrytis is developing.

Lisa Jones, 2015.

Botrytis readily colonizes dead tissue as seen on this spent lilac flower.

Lisa Jones, 2015.

Cause Pseudomonas syringae pv. syringae, the bacterium that also causes bacterial blight of pear, blueberry, cherry, maple, and many other woody plants. Losses can be substantial due to this disease in nursery production. Older landscape plantings can still thrive despite high disease pressure. Bacteria overwinter on diseased twigs or as epiphytes on healthy wood. Factors that weaken or injure plants predispose them to disease.