Ophistoma ulmi  (Ceratocystis ulmi)   (fungus)

Spread by Vectors that are native and European Elm Bark Beetles.

All native Ulmus (Elm) species: European and Asiatic elms and Zelkova moderately resistant; cultivars of U. carpinofolia resistant are at risk almost anywhere elms grow in north America.

Contributors are elm bark beetles; drought, malnutrition, construction impact; elm firewood or slash, infected elms within 700 feet; climbing spurs.

Watch for yellowing and wilting of terminal leaves in late spring; browning and premature dropping. Twigs tend to turn inward (“shepherd’s crook”). Twig crotches notched by beetle entry. Late spring infection with terminal foliar tufts and sparse leafing; meager chlorotic foliage next spring. Spreads rapidly,  one branch at a time. This kills tree by end of summer; larger trees may survive several years. Mid-summer infection shows on a few branches, becoming severe the next year. Late summer infection stable until next spring, or tree may be free from symptoms next year. Sapwood of infected branches streaked tan or brown. Beetle galleries under bark of larger branches and stems of dying trees. Root graft infection likely where driplines meet, followed by rapid wilting uniformly distributed around crown. Positive identification only by culturing the fungus pathogen in the laboratory.
Overwintering occurs in infected trees, logs, or stumps. Fungus carried by elm bark beetles laying eggs in dying elms; hatch in late fall; larvae tunnel under bark. Larvae develop into pupae the next spring, emerging as adults. Spores in larval galleries sticky, collecting on emerging beetles. Sometimes 3 generations annually. Transmission also through root grafts.

TWIG CANKER
Vermicularia ipomearum (imperfect fungus)

 All American and Siberian elms are effected throughout the United States: Western Plains states and central California.

Wet spring seems to favor development.

Seen as Small, black, girdling cankers on small twigs, leading to limited dieback (not significant).

Tiny, hairy, black fruiting structures (pycnidia) at edges of small, round, grayish cankers on small twigs in late spring. These cankers enlarge each season until the twigs are girdled. The pycnidium is globose, leathery black, with dark-colored bristles. The conidia are elongate, single-celled, slightly curved. They are produced abundantly, reinfecting the tree.

Pyrrhalta luteola (beetle)

The Adults are Yellow to dull green with black stripe along sides; approximately 1/8 in. long. antennae and legs; yellow, eyes; black, head and thorax has black spots. The egg coloring is orange-yellow. The Larvae is tiny, black, grub-like; (later) yellow spotted with black, eventually growing to approximately 3/8 in. long.

All species of elm and Japanese zelkova are hosts and are found throughout United States and Canada; wherever elms and zelkova grow.

Reconized by massive adult activity around hibernation sites as weather warms (bud break). Upon reaching trees, adults chew circular holes in expanding leaves. Eggs deposited on undersides of leaves in groups of up to 25. One female may lay 800 eggs per generation, 25 at a time.Tiny black larvae feed on undersides of leaves, eventually skeletonizing them with only upper surfaces and veins remaining. Pupae are in crevices, in the bark, or on the ground, and under protected areas nearby. Repeated attacks annually can kill major branches or an entire tree.

Elm Leaf Beetle hibernate as adults in attics, patios, under shingles, becoming a nuisance in autumn. Become a nuisance again in the spring when they migrate back to trees at bud break to lay eggs on expanding leaves.

Oviposition begins in late May and lasts several weeks. Larvae hatch in about a week , feeding on the undersides of the leaves until fully grown. They then crawl away to pupate in the crevices of bark, on the ground, or in branch crotches. Larval stage lasts 2-4 weeks, and the pupal stage about 10 days. There may be from two generations in the northeast to four in the south and west, depending on the weather. The first generation is generally the most damaging.

Gossyparia  spuria
European elm scale is often first noticed on urban elms when honeydew produced by feeding scales becomes a nuisance on parked cars or outdoor furniture. Branches on infested trees are typically blackened by sooty mold growing on the honeydew. Closer examination of the branches reveals female scales, which appear as gray or reddish brown discs surrounded by a white, waxy fringe less than 1/8-1/2 inch (<10 mm) long (fig. 1). Tiny, orange crawlers can be seen on leaves along main veins in summer (fig. 2).

Most Elms (Ulmus) species are effected , (primarily American elm), Chinese Elms and other Elms
Eggs hatch in June and July from beneath mature female scale coverings. Summer is spent as tiny, yellow nymphs on the undersides of leaves. The insects crawl back to branches in late summer and attach themselves to twigs and branches. Female scales cover their bodies with a gray, waxy covering, and they overwinter in the second instar. Winged and unwinged males, when present, overwinter in small white cocoons. In spring, females grow and become a dark red-brown and produce copious amounts of honeydew. Reproduction can be sexual or asexual.

The damage is seen by honeydew dropping, sooty mold on leaves.
European elm scale feeding can be a nuisance but heavy infestations cause yellowing leaves that may drop early, and heavy feeding can cause branch dieback or death of trees.

Dothiorella ulmi   (imperfect fungus)

Common to American elms. Occasionally on slippery and Siberian elms located in central and eastern United States.

Wounding, insect punctures, pruning, compacted soil, drought, malnutrition, overhead irrigation, climbing spurs all add to infections.

 The foliage yellows and wilts in scattered portions of crown with wilt becoming generalized throughout, followed by gradual dieback. Outer rings of wood have brown discoloration. Elliptical cankers on stems with small black specks of spore bodies (pycnidia). In wet weather, sticky spore masses accumulate around wounds or on leaves. Wilt symptoms resemble those caused by other wilt fungi. Laboratory isolation is necessary for positive diagnosis and identification.

There are sticky spore masses on leaves or twigs spread by wind, rain, overhead irrigation, and pruning. Infection usually through wounds on leaves, but may enter through stem wounds. The fungus moves down leaf petioles into twigs, entering and plugging vessels. Cankers develop around such infection sites. New pycnidia develop during summer and autumn, releasing spores during spring rains.

Agrilus planipennis (Coleoptera: Buprestidae)

Adults are larger and a brighter green than any of the native North American species of Agrilus. They are slender, elongate adults are 7.5 to 13.5 mm long; females are larger than males. The larvae reach a length of 26 to 32 mm, are cream-colored and dorso-ventrally flattened . Their brown head is mostly retracted

Ash Trees (Fraxinus sp.) are their host trees and are found in China, Japan, Korea, Mongolia and eastern Russia (Yu 1992), was unknown outside of Asia until it was discovered in Michigan and Ontario in June, 2002. They have spread to many U.S. States and seem to be be spreading nationwide.

Poor sites, drought, nutritional deficiencies, wounding, root compaction and food supply seem to be contributing causes for infestaions.

They can be recognized by their Serpentine galleries excavated by feeding larvae disrupt nutrient and water transport, causing branches and eventually the entire tree to die. Ash trees of all species and size, regardless of growing conditions, have died within 1 to 4 years of initial infestation.

Adult emergence begins in mid to late May, peaks in early to mid June, and continues into late June. The adults are active during the day, particularly when conditions are warm and sunny. Most beetles remain in protected locations in bark crevices or on foliage during rain, heavy cloud cover, high winds or temperatures above 32°C (90°F). The beetles usually fly within 2 meters of the ground. Adults, which are present into August, feed on up to 0.45 cm2 of foliage per day, leaving irregularly-shaped patches of leaf tissue with jagged edges. Male adults live an average of 13 days and females live about 21 to 22 days. Females can mate multiple times and oviposition begins 7 to 9 days after the initial mating. Females lay 65 to 90 eggs during their lifetime. Eggs are deposited individually on the bark surface or in bark crevices on the trunk or branches. Eggs hatch in 7 to 10 days. After hatching, first instar larvae chew through the bark and into the cambial region. Larvae feed on phloem and the outer sapwood for several weeks. The S-shaped feeding gallery winds back and forth, becoming progressively wider as the larva grows. The insect overwinters as a full-grown larva in a shallow chamber excavated in the sapwood. Pupation begins in late April or early May. Newly enclosed adults may remain in the pupal chamber for 1 to 2 weeks before emerging head-first through a D-shaped exit hole that is 3-4 mm in diameter.

ENGRAVERS (Conifers  AKA..Pine Bark Beetles)
Ips spp., and Others  (beetle)
Their larvae are very small (3/16 in. long when mature) and white, while adults are 1/10-3/8 in. long; red brown to black, shiny with parallel sides; 3-6 spinesat ends of wings.

Tunnels or gallaries are curved, S-shaped, or inverted-Y, tortuous or straight and parallel.
Many various pines, Douglas fir, fir, and spruce are their host trees.
Found throughout the United States: Alaska, east, southeast, Canada, British Columbia, Quebec to Nova Scotia.

Poor site, drought, injuries, nutritional deficiencies will attract them to weakened trees.
Dieback occurs on the upper terminals and laterals branches tunneling under the  bark with egg galleries with 3 or more larval mines issuing from each egg pocket.

The rapidity of development and number of generations varies with different seasons and localities. Usually 1-3 summer generations and 1 overwintering. Overwinter as adults, larvae, or pupae beneath the bark of trees killed the previous season. Attacks may be primary or secondary.

Phoracantha semipunctata, P. recurva

Adult eucalyptus longhorned borers have shiny, dark brown and yellow to cream-colored areas on their wing covers. The antennae are as long or longer than the body, and the antennae of males have prominent spines. Mature larvae may be large (more than 1 inch long) and are cream colored and legless. Females lay eggs under loose bark or in crevices on bark surfaces. If conditions are ideal, larvae will bore directly into the inner bark after hatching. If conditions are less than ideal, the small larvae feed outward from the egg mass, leaving a distinct dark trail (1/4 inch to several inches long), that scores the bark surface, before they bore into the cambial tissue on its inner surface. Once the larvae have bored into the inner bark, the galleries they form beneath the wood surface can extend several feet. In trees with heavy infestations, the scraping sounds made by the developing larvae chewing into the cambium are clearly audible from a distance of several feet.

 Eucalyptus. globulus, E. grandis, E. diversicolor, E. viminalis, E. nitens, E. saligna, E. sideroxylon, camaldulensis, E. robusta, E. citriodora, E. dalyrmpleana, E. cladocalyx are amoungst their host trees.

Since its 1984 discovery in southern California, the eucalyptus longhorned borer has steadily expanded wherever eucalyptus grow.

 Longhorned borers mostly attack stressed or damaged plants; vigorous, well-watered trees are rarely attacked. However, in California many eucalyptus trees are seasonally water-stressed during hot summer months, rendering a significant proportion of them susceptible to the beetle.

Copious bleeding from egg laying sites often indicates initial borer attack.

Symptoms include wilting of foliage and the dieback of treetops, branches, or entire trees. Mining of bark and cambium, sometimes girdling stems or roots of young trees; tunnels through sapwood and into heartwood, filled with frass.

The female beetles begin laying eggs in groups of 3 to 30 under loose bark. They may lay up to 300 eggs, which hatch in about 1 to 2 weeks depending on temperature. First-instar larvae may bore directly into the inner bark or in the outer bark layers, before turning inward to mine at the bark-cambium-xylem. Larvae require about 70 days to develop in fresh wood or logs during hot summer months, and up to 180 days in drier logs. Following pupation, adult beetles emerge from the same holes. During spring and summer, the beetle requires 3 to 4 months to complete its life cycle. Starting in fall and winter, it may require up to 9 months.

Neodiprion sertifer
Pine Sawfly are distributed throughout the area where their preferred hosts grow.
Species of Pine Sawfly will infest eastern white pine, P. strobus; Austrian pine, P. nigra; ponderosa pine, P. ponderosa; shortleaf pine, P. echinata; and pitch pine, P. rigida, if they grow in close proximity to preferred pines.t, P. strobus; Austrian pine, P. nigra; ponderosa pine, P. ponderosa; shortleaf pine, P. echinata; and pitch pine, P. rigida, if they grow in close proximity to preferred pines.

Conifer sawflies are a unique group of defoliating insects.

The larvae are host specific and feed on old and current year foliage at some point in their development. Some species have one generation per year with defoliation occurring in the spring and others produce three or more generations with defoliation occurring on into fall. Fall defoliation has a greater impact on trees and it is for this reason that sawflies having multiple generations are considered more devastating.

Sawfly adults resemble large houseflies but are actually primitive broad-waisted wasps. While true flies have one pair of wings, the sawfly has two pairs of wings. The females are equipped with an ovipositor that is serrated, which enables them to saw little slits in the needles where eggs are laid, thus the name “sawflies”.

Defoliation by sawflies is sporadic, occurring in localized or region-wide outbreaks lasting one or more years. Growth loss the year following a severe defoliation (greater than 75%) can average over 50% and mortality increases due to secondary invasion by bark beetles and pine sawyers.

During September and October females slit the edges of pine needles with saw-like structures on the tip of their abdomens and lay eggs into these openings. Females usually select needles grown that year located near the end of a lateral branch. Typically, one female will lay 6–8 eggs in a single needle in each of approximately 10–12 needles. Only one generation occurs per year and this species overwinters as eggs. Hatching occurs from late April through early May and larvae begin to feed in groups on the previous year’s needles and sometimes the bark of new shoots. If larvae defoliate the tree of last year’s needles before reaching maturity, they will crawl to another host tree to continue feeding. In late May and early June mature larvae usually drop to the ground to prepare to undergo the transformation to the pupal stage. In late August mature larvae begin to pupate inside tough, golden brown cocoons in the leaf litter. Adults emerge from early September until late fall.

The larval stage of this pest causes damage to several different species of pine. It prefers mugo pine, P. mugo; Scots pine, Pinus sylvestris; red pine, P. resinosa; jack pine, P. banksiana; Japanese red pine, P. densiflora; and table mountain pine, P. pungens.

Young larvae eat the surface of the needle causing needles to appear dry and strawlike. Older larvae continue to eat the needles from tip to base. Repeated defoliation severely stunts the growth of the tree and results in a thin, unsightly appearance. This aesthetic damage is most apparent on mugo pine in landscapes and nurseries and Scots pine grown in Christmas tree plantations. Since larvae rarely attack new foliage and most trees are seldom entirely defoliated, pines usually survive an infestation.
Although larvae can also feed on the bark of new shoots causing shoot deformation and twig mortality.14