Saturday, February 28, 2009

Nursery, Greenhouse, and Landscape - Late Winter Notes

The following are some late winter notes for nurseries, greenhouses, and landscape companies.

CANKER - Early spring is a good time to look around your yard for signs of winter damage, breakage of limbs, and cankers that may not be noticeable once trees and shrubs leaf out. Cankers caused by Botryosphaeria or other fungal opportunists will often appear as sunken, target-shaped or oval areas on branches. Trim back behind the canker before new growth begins.

Botryosphaeria canker. Photo by Theodor D. Leininger, USDA Forest Service,

ROOT ROT - The Diagnostic Clinic has received samples of pansies with poor growth and blackened roots. These plants are infected with the black root rot fungus, Thielaviopsis. Once established in your garden soil, this fungus can persist and cause problems on other annuals such as petunia and vinca. Check your new plants before planting to be sure root systems look light in color and healthy.
Black root rot causing pansy decline.

INSECTS and TEMPERATURE. Spring is quickly approaching and some arthropod pests we may find active in early spring are eastern tent caterpillars, white pine sheath mites, spruce spider mites, and juniper webworms. Did our colder winter have an impact on insect populations? Insect species are affected by cold temperatures differently, so some arthropod populations may decrease while others are unaffected. When your customers ask you to predict pest problems based on the type of winter we’ve had, there really is no simple answer.
Spruce spider mites. Photo by Petr Kapitola, State Phytosanitary Administration,

Information from the resubscription notice of the 2009 Ornamentals Hotline newsletter from the University of Delaware Cooperative Extension.

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