In March NMPRO we identified some of the most unwanted pests in the nursery industry. This month we’re bringing control measures to your attention. When applicable, both chemical and biological options are available. Keep in mind not all chemicals are registered in all states. And be aware that quarantines -- federal or state -- may affect the way pests are managed. Check with your state department of agriculture or your local extension office for help.
Asian longhorn beetle
Scientific name:Anoplophora glabripennis.
Description: Adults are 1 inch to 1 1/2 inches long with long antennae. The body is shiny and black with white markings on both the body and the antennae.
Hosts: Hardwoods, including several maple species (Norway, sugar, silver and red maple), box elder, horsechestnut, buckeye, elm, London plane, birch and willow.
Symptoms: As the adult chews its way out of the tree, it leaves behind round 3/8-inch holes with frass and sap.
Control: Imidacloprid applied through either tree trunk or soil injections under USDA supervision. The number of injections required depends on the size of the tree.
Photo by Michael Smith
Chilli thrips
Scientific name: Scirtothrips dorsalis Hood.
Description: Field identification of S. dorsalis is extremely difficult and often impossible to differentiate from other thrips in the field. Adults have a pale body with dark wings and are less than 2 mm long. Immature S. dorsalis thrips are pale many other thrips species.
Hosts: There are more than 100 reported hosts, but some common landscape hosts include roses, ligustrum, lisianthus, pittosporum, herbs, begonia and Indian hawthorn. The pest also threatens cotton, peanuts, grapes, tomatoes and hot peppers.
Symptoms: The pest is mainly a forage feeder, preferring new leaves and buds. Feeding damage turns tender leaves, buds and fruits bronze. Damaged leaves curl upward and appear distorted. Infested plants become stunted or dwarfed, and leaves with petioles detach from the stem, causing defoliation in some plants. Feeding on buds may cause them to become brittle and drop.
Control: Abamectin, acephate, chlorfenapyr, cyfluthrin + imidacloprid, dinotefuran, imidacloprid and spinosad.
Emerald ash borer
Scientific name:Agrilus planipennis Fairmaire.
Description: Adults are roughly 3/8 to 5/8 inch long with metallic-green wing covers and a coppery-red or purple abdomen.
Hosts: Fraxinus spp.
Symptoms: Larvae feed in the phloem and outer sapwood, producing galleries that eventually girdle and kill branches and entire trees. Adult beetles leave distinctive D-shaped exit holes in the outer bark of the branches and trunk.
Control: Imidacloprid, bidrin, cyfluthrin, bifenthrin and carbaryl.
Gypsy moth
Scientific name:Lymantria dispar.
Description: Egg masses are beige and about the size of a quarter. Caterpillars are 1 to 2 inches long when fully grown, with hairlike structures along the entire length of their bodies. Grayish, with five pairs of blue spots and six pairs of red spots along their backs, the caterpillars have yellow markings on their head. Male moths have a wingspread of about 1 inch. They are light tan to dark brown and have blackish wavy bands across their forewings with arrowhead markings near the leading edge. Female moths are nearly white with faint, dark wavy bands on the forewings.
Hosts: More than 500 species of trees and shrubs.
Symptoms: Look for egg masses, caterpillars and defoliation.
Biology: Egg masses appear in July and August. Larvae emerge the following April or May and begin devouring leaves. The caterpillar stage lasts 10 to 12 weeks. Transformation from caterpillar to moth takes place during a 10- to14-day period. From June to August, larvae enter the pupal, or resting stage.
Chemical control: Diflubenzuron.
Biological control: Dispalure pheromone, Bacillus thuringiensis (Bt), gypsy moth nucleopolyhedrosis virus (NPV).
Imported fire ants
Scientific name:Solenopsis invicta Buren, S. richteri Forel, and their hybrid.
Description: Identifying fire ants is difficult because they look much like ordinary ants. They are 1/8 to 1/4 inch long and reddish brown to black. Fire ants are probably best distinguished by their aggressive behavior and characteristic mound-shaped nests.
Hosts: Buds and fruit of nursery and agriculture stock, pets, wildlife and humans.
Symptoms: These insects feed on buds or fruits of many plants and may remove bands of bark from young citrus trees, often killing them. Their hard, cone-shaped mounds can get as high as 2 feet. They’re a major threat to livestock and humans because of their aggressive nature and painful stings.
Chemical control: Emersion -- emulsifiable chlorpyrifos; drenching (containers) -- chlorpyrifos, diazinon, bifenthrin; drenching (B&B) -- chlorpyrifos; topical -- bifenthrin; granular in potting media -- bifenthrin, tefluthrin or fipronil; in-field treatment for B&B -- sequential application of fenoxycarb, hydramethylnon, methoprene or pyriproxyfen bait followed by a broadcast application of granular chlorpyrifos.
Biological control: Phorid flies -- adult females deposit eggs inside the fire ant. The larva uses the ant’s head as a protective case and completes its development. Just before the fly pupates, the ant’s head falls off.
Light brown apple moth
Scientific name:Epiphyas postvittana.
Description: The adult moth is about 10 millimeters long when resting with the wings folded in a characteristic bell shape. It’s generally yellowish-brown with darker-brown markings on the forewings. The females often have a dark spot on the hind margin of the forewing. Adult moths must be identified by a qualified entomologist. Caterpillars are tiny with a pale-yellow-green body and a pale-brown head. The pupa is green at first, but soon becomes brown after rapidly hardening, and then darkens during development. The pupa is typically found in a thin-walled silken cocoon between two leaves webbed together.
Hosts: More than 1,000 plants, including cypress, redwood, oak and stone fruit.
Symptoms: The pest destroys, stunts or deforms young seedlings; spoils the appearance of ornamental plants; and injures deciduous fruit-tree crops, citrus and grapes.
Chemical control: Chlorpyrifos and phosmet.
Biological control: Pheromone (Tetradecen-l-yl acetate), Trichogramma (wasps), Bt.
Pine shoot beetle
Scientific name:Tomicus piniperda L.
Description: Adult pine shoot beetles are 3 to 5 millimeters long, or about the size of a match head. They are brown or black and cylindrical. The legless larvae are about 5 millimeters long with a white body and brown head.
Hosts: Scotch pine (Pinus sylvestris) is the principle host, but other pine species are susceptible.
Symptoms: The beetle attacks new pine tree shoots, stunting the growth. It may also attack stressed pine trees by breeding under the bark at the base of the trees. Affected shoots droop, turn yellow and eventually fall off during summer and fall.
Chemical control: No practical chemical control.
Biological control:Thanasimus formicarius Linnaeus (predatory beetle).
Pink hibiscus mealybug
Scientific name:Maconellicoccus hirsutus.
Description: It’s reddish-brown or pink and absent of fringe and stripes on the back. It has very little wax on the body. Anal filaments are short and the ovisac is irregular and located beneath the body. When crushed, body fluid is dark red. Eggs are bright pink to red.
Hosts: More than 300 species, including Allamanda, Angelica, Anthurium, Bougainvillea, Croton, ginger lily, Heliconia, Ixora, hibiscus, palm and oleander.
Symptoms: Feeding causes new leaves to curl, giving a “bunchy top” appearance. Like other mealybugs, pink hibiscus mealybugs (PHM) excrete honeydew, which turns leaves shiny at first and then black, as sooty mold grows on the accumulated honeydew.
Chemical control: For quarantine treatment -- Imidacloprid, dinotefuran, thiamethoxam, bifenthrin, chlorpyrifos, acephate. For preventative treatment -- acetamiprid, chlorpyrifos, acephate, bifenthrin, buprofezin, pyrproxyfen, imidacloprid + cyflurthrin.
Biological control:Anagyrus kamali and Gyranusoidea indica (parasitoids).
Red palm mite
Scientific name:Raoiella indica Hirst.
Description: Red mites are usually found on the undersides of leaves and are often in groups of hundreds of individuals visible with the naked eye. Cast skins are white and are often more numerous than living mites.
Hosts: The pest primarily infests palms and bananas, but has been found infesting gingers, heliconias and other ornamentals.
Symptoms: Feeding mites, especially at high densities, cause localized yellowing of leaves followed by tissue necrosis.
Chemical control: An effective chemical has not yet been identified.
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Biological control: Amblyseius channabasavanni Gupta (predatory mite)
- Kelli Rodda
April 2008