Azalea Lace Bugs (802-1029 GDD = 3^rd generation): The third generation of this pest will be in full swing for much of NJ by the end of the month. Look for the presence of nymphs (spiny, black), adults (larger, lacy wings), fecal spots (brown, shiny spots) on the underside of leaves, and stippling (feeding damage from nymphs and adults) on the leaves. Remember that the yellow stippling damage persists on the leaves until they are dropped. Look for the presence of actively feeding lace bug nymphs or adults before treating plants.

Azalea lace bug stippling symptoms on Azalea leaves. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

Azalea leaf undersides with frass spots & egg laying along mid-rib. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

When found, use horticultural oil (only if a spray can contact the back of the leaves), or acephate (Orthene) if the shrub is too dense to allow effective use of oil. Imidacloprid (Merit) applied to soils now may require 1-2 weeks before they begin to control this second generation or the beginning of the third generation (longer if soils are dry). Chlorantraniliprole is a reduced-risk insecticide that can be effective against lace bugs. Remember that stressed azaleas in full sun are more prone to lace bugs. Also, & more importantly, predators will be fewer in full-sun locations.

Azalea lace bug adult with oval shaped wings. Lace bug species having oval shaped wings will only feed on broad-leaf evergreens. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

The Landscape Pest Notes for Late June 2023 in addition to the azalea lace bugs also includes information & photographs of oak spider mites, two-spotted spider mites, pine spittlebugs, mimosa webworms, various soft scales, white prunicola scales, red-headed flea beetles & tree species prone to mid-season leaf drop.

[Read more…]

Boxwood Spider Mite: (GDD =450-700) (PPI = Kousa Dogwood; Cranberry Bush) This spider mite, which attacks all boxwoods, is neither a true cool nor warm season mite species. It is usually most active with intermediate temperatures during late spring & early summer. The adult is yellow-tan in color with long legs. When the boxwood mites are active, they can be found on both the top & bottom of new growth. Eggs are light yellow & overwinter on leaves & twigs. There are several generations per year.

Boxwood spider mite feeding damage results in foliage with yellow to bronze stippling, which may resemble injury caused by thrips. Both of these insects cause distinctive linear stippling streaks. These symptoms can be diagnostic when observed on foliage. With high mite populations, entire leaves may develop yellowish-white streaks; premature defoliation can occur.

Boxwood spider mite feeding symptoms. This mite species creates linear streaks on leaves. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

Boxwood spider mite symptoms that are more mild. The distinctive linear streaks are more clearly observed. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

Detected overwintering eggs are treated with dormant oils (2-3%). Although normally unnecessary, summer oils (1-2%) or insecticidal soaps are recommended to control mild mite populations. With high infestations, some reduced-risk materials include spinosad, spiromesifen, acequinocyl, & bifenazate. Examples of other materials include hexythiazoc, abamectin, fluvalinate & acephate. Be aware that fluvalinate is a pyrethroid & can promote spider mite resurgence. Acephate may only provide mite suppression.

The Rutgers Plant & Pest Advisory Blog for Early June 2023 includes some commonly observed insect/mite & disease pests within the landscape during the late weeks of spring & early weeks of summer. In addition to boxwood spider mites, the other insect/mite pests included are juniper scale, bagworm, black vine weevil, bronze birch borer, pear leaf blister mite, & beneficial predacious mite. The disease pathogens included are fire blight, oak leaf blister fungus, black spot of rose, powdery mildew & Verticillium wilt. Some suggested monitoring techniques & variables are listed between the insect/mite & disease pests.     

[Read more…]

Artillery Fungus (Sphaerobolus): This wood decomposer is found in mulched areas and has probably caused the most concern to landscapers and potentially poses some economic concern to their clients. This fungus produces fruiting structures that resemble tiny cream or orange-brown cups that hold a spore mass resembling a tiny black egg (0.1 inches in diameter). When enough water accumulates, the spores are shot high into the air up to several yards. The dark-colored spores resemble small tar spots and will stick to house siding, downspouts, cars, leaf surfaces, and any nearby structure. The artillery fungus is strongly phototrophic & will shoot its spores toward light sources or white-colored surfaces. The spores have extreme adhesive qualities & are difficult to remove, even with high-pressure sprayers.

The black colored spores of Artillery Fungus can also be mistaken for pests (e.g., scales) when stuck on the undersides of plant leaves. (Photo Credit: Tim Waller, Rutgers Coop. Ext.)

Artillery Fungus black spores can mare the surface of white siding on houses. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

The Landscape Pest Notes Blog for Late May 2023 reviews a dozen insect & disease pests that are commonly observed during the second half of May within NJ landscapes & nurseries. The insect pests highlighted include the elongate hemlock scale, pine needle scale, Euonymus scale, Taxus mealybug, four-lined plant bug, & aphids.  In addition to the artillery fungus, the other fungal organisms included are black sooty mold, Volutella blight, cedar rust diseases, Cytospora canker, & Botrytis.      

[Read more…]