Identifying Pest Problems

When it comes to solving pest problems on ornamental plants in the landscape, positive identification and correct diagnosis is essential for control and elimination of insects and diseases, pointed out Vinnie Drzewucki, certification chair, Long Island Nursery & Landscape Association in New York.

To help lawn care operators properly identify pest problems, Drzewucki pointed out a few common plant symptoms and their causes:

·        SYMPTOMS: Ragged leaves, holes in wood and bark or in fruit and seeds, serpentine mines or blotches, wilted or dead plants

CAUSE: Insects with chewing mouthparts

·        SYMPTOM: Yellowing and wilting leaves, dying or dead sections or entire plant dies

CAUSE: Bacterial and viral infections often spread by insects, i.e. Dutch Elm Disease spread by elm bark beetle

·        SYMPTOMS: Leaves usually off-color, round leaf spots, evidence of scorch or hopper burn, wilted or misshapen foliage and fruit

CAUSE: Insects with sucking mouthparts such as aphids, lacebugs or mites

·        SYMPTOMS: Scars formed on stems, twigs, barks or fruit

CAUSE: Oviposition scars formed by female insects during egglaying

·        SYMPTOMS: Clear, sticky coatings on leaf surfaces, honeydew deposits often accompanied by the growth of a black, sooty mold (black fungus) on leaves, twigs and buds

CAUSE: Insects with sucking mouthparts such as aphids, lacebugs or leafhoppers

·        SYMPTOMS: Yellowing, wilting, scorched leaves, dead branches, death

CAUSE: Fungus caused by diseases that clog water-conducting cells and plug the vascular system, which conducts food and water throughout the plant, i.e. verticillium wilt on Norway maple

·        SYMPTOMS: Brown or black spots or blotches on leaves, fruit rot, scab, rust pustules, powdery mildew

CAUSE: Fungus that destroy or damage leaves or fruit, i.e. anthracnose on dogwoods

·        SYMTOMS: Wilting, yellowing or stunted plants, rotted roots, death

CAUSE: Fungus that destroy or damage roots, i.e. root rot caused by botrytis

·        SYMPTOMS Unusual, swollen growth on flowers, leaves, twigs or roots

CAUSE: Fungus (sometimes insects) that cause galls, cankers and overgrowths

·        SYMPTOMS: Mushy, rotten tissue below ground on roots, tubers and rhizomes of herbaceous plants; yellowing, stunting and death of above ground plant parts

CAUSE: Soil borne fungus or bacterial infections

 The author is managing editor, Lawn & Landscape, and can be reached at nwisniewski@lawnandlandscape.com.