Elms are deciduous and semi-deciduous trees comprising the flowering plant genus Ulmus in the plant family Ulmaceae. The genus first appeared in the Miocene geological period about 20 million years ago, originating in what is now central Asia. These trees flourished and spread over most of the Northern Hemisphere, inhabiting the temperate and tropical-montane regions of North America and Eurasia, presently ranging southward in the Middle East to Lebanon, and Israel, and across the Equator in the Far East into Indonesia.
Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A typical life cycle involves flightless females giving live birth to female nymphs—who may also be already pregnant, an adaptation scientists call telescopic development—without the involvement of males. Maturing rapidly, females breed profusely so that the number of these insects multiplies quickly. Winged females may develop later in the season, allowing the insects to colonize new plants. In temperate regions, a phase of sexual reproduction occurs in the autumn, with the insects often overwintering as eggs.
There are a number of lines of defence against pests and diseases in the orchard, principal among these being the practice of good husbandry, creating healthy soil and ensuring high standards of garden hygiene. But no matter how diverse and healthy the garden eco-system may be, there will always be a degree of disease and pest presence. In many ways, some level of pathogen population in the garden can be not only acceptable but desirable as they are indicative of a generally healthful and diverse environment, and add to the overall robustness of the system as an immunity to such detrimental influences will build up, particularly in a balanced polycultural regime. Indeed, most of the plants we grow will tend to be selected because they are trouble free, and those that are more susceptible to attack will have fallen by the wayside over time. However, most farmers find it unacceptable that the food crops they grow are damaged by pests.
Woolly aphids are sap-sucking insects that produce a filamentous waxy white covering which resembles cotton or wool. The adults are winged and move to new locations where they lay egg masses. The nymphs often form large cottony masses on twigs, for protection from predators.
The American Elm cultivar Ulmus americana 'New Harmony' was raised by the Maryland Agricultural Research Service and released by the United States National Arboretum in 1995, along with 'Valley Forge'. 'New Harmony' proved the most successful U. americana cultivar in the US National Elm Trial, averaging a survival rate of 85.5% overall.
Ophiostoma ulmi is a species of fungus in the family Ophiostomataceae. It is one of the causative agents of Dutch elm disease. It was first described under the name Graphium ulmi, and later transferred to the genus Ophiostoma.
The Adelgidae are a small family of the Hemiptera closely related to the aphids, and often included in the Aphidoidea with the Phylloxeridae or placed within the superfamily Phylloxeroidea as a sister of the Aphidoidea within the infraorder Aphidomorpha. The family is composed of species associated with pine, spruce, or other conifers, known respectively as "pine aphids" or "spruce aphids". This family includes the former family Chermesidae, or "Chermidae", the name of which was declared invalid by the ICZN in 1955. There is still considerable debate as to the number of genera within the family, and the classification is still unstable and inconsistent among competing authors.
Platychora( also known as Platychora ulmi Duval ) is a genus of fungi in the family Venturiaceae. Platychora ulmi is a plant pathogen infecting elms.
In the 10th edition of Systema Naturae, Carl Linnaeus classified the arthropods, including insects, arachnids and crustaceans, among his class "Insecta". True bugs and thrips were brought together under the name Hemiptera.
Aphelinus mali is a parasitoid wasp that exploits the woolly apple aphid, a pest of apple trees. It is native to the northeastern United States but has been introduced to other parts of the world as a biological pest control agent.
Prociphilus is an aphid genus of the subfamily Eriosomatinae, which cause the plants they attack to produce galls. The aphids reside and feed within the gall.
Eriosoma lanigerum, the woolly apple aphid, woolly aphid or American blight, is an aphid in the superfamily Aphidoidea in the order Hemiptera. It is a true bug and sucks sap from plants.
Anthocoris gallarumulmi is a true bug in the family Anthocoridae. The species is a West Palearctic species found on aphid-galled leaves of Ulmus minor and is a predator of the aphid Eriosoma ulmi It is also associated with aphid-leaf galls of Fraxinus excelsior, Ribes, Prunus spinosa and Crataegus monogyna.
Grylloprociphilus is a genus of woolly and gall-making aphids in the family Aphididae. There is at least one described species in Grylloprociphilus, G. imbricator.
Phyllaphis is a genus of aphids in the family Aphididae. There are at least four described species in Phyllaphis.
Tetraneura ulmi, the elm sack gall aphid and also known as a fig gall, is a species of aphid in the family Aphididae. It was described by Carl Linnaeus and named in his Systema Naturae, published in 1758. The mite is found in Asia, Europe and North America, causing abnormal plant growths, known as galls on their primary host, elm trees (Ulmus species). They feed on a secondary host, the roots of various grasses.
Tetraneura is a genus of woolly and gall-making aphids in the family Aphididae. There are more than thirty described species in Tetraneura.
Cerataphis is a genus of witch hazel and palm aphids in the family Aphididae. There are about 10 described species in Cerataphis.
Prociphilus tessellatus, known generally as the woolly alder aphid or maple blight aphid, is a species of aphid in the family Aphididae.
The woolly elm aphid is an aphid native to North America, found where Saskatoon and American elm trees are established.
