June 28, 2022

The Canadian Council on Invasive Species (CCIS) gave a short presentation of the top 10 invasive species already in Canada or that could come to Canada from south of our border and that we therefore should be on the alert for. 

The top 10 invasive species were as follows:

Asian long-horned beetle, Anoplophora glabripennis

Spotted lanternfly, Lycorma delicatula

Asian giant hornet, Vespa mandarinia

Emerald ash borer, Agrilus planipennis

Hemlock woolly adelgid, Adelges tsugae

Brown marmorated stink bug, Halyomorpha halys

Dutch elm disease, Ophiostoma ulmi and Ophiostoma novo-ulmi

Japanese beetle, Popillia japonica

Spongy moth (also LDD moth; previously gypsy moth), Lymantria dispar dispar

Lily leaf beetle, Lilioceris lilii

I have definitely seen at least three of these species and/or the damage they have done, specifically 4, 8, and 9. 

You can help by reporting these species through, for example, iNaturalist. CCIS has their own project on iNaturalist, titled “I Spy and Identify Invasives / Je vois, J’identifie les espèces envahissantes”, which you can join: https://www.inaturalist.org/projects/i-spy-and-identify-invasives-je-vois-j-identifie-les-especes-envahissantes. The CCIS also has a whole webpage on how and where to report: https://canadainvasives.ca/take-action/report/.

Ulmen handbuch zur

  ULMEN HANDBUCH ZUR >> DOWNLOAD LINK vk.cc/c7jKeU

  ULMEN HANDBUCH ZUR >> READ ONLINE bit.do/fSmfG

        ulmen-arten laubenulme krankheiten

  Die Ulmengewächse (Ulmaceae) umfassen sieben Gattungen mit rund 60 bis 70 Arten, die in den tropischen, subtropischen und vor allem in den gemäßigten Zonen der Familie, Ulmengewächse (Ulmaceae). Gattung, Ulmus. Art, minor Mehr Infos unter ulmen-handbuch.de/handbuch/ulmus/u_minor.html. Das Handbuch der Ulmengewächse bietet einen Gesamtüberblick über die Familie der Ulmengewächse im allgemeinen und die eigentlichen Ulmen (Gattung: Ulmus) im (2016b): Handbuch der Ulmengewächse. Version 2.0. Im Internet unter: ulmen-handbuch.de. [30] MACKENTHUN, G. (2016c): Ulmen für die Zukunft Ulmen sind eigentlich die idealen Stadtbäume. Leider wurden die meisten Ulmen durch die Ulmenwelke in den letzten ulmen-handbuch.de. Gordon Mackenthun aus dem Jahr 2010 als die höchste bis dahin bekannte Bergulme in Europa. ulmen-handbuch.de/handbuch/ulmus/u_glabra.html". 2020) wurden die Ulmen auf 60 Untersuchungsflächen (je 2500 m2) des Projekts "Lebendige Luppe" kartiert. Im Herbst 2020 erfolgte eine Artbestimmung derDort kommen ebenfalls Ulmen vor und dort kommt auch ein Pilz, Ophiostoma himal-ulmi, vor, der mit dem Erreger eng verwandt ist. Allerdings hatten Wirt und

https://hevaxadoher.tumblr.com/post/691895287443243008/zircon-multiscanner-pro-sl-bedienungsanleitung-hd, https://jipececimumu.tumblr.com/post/691895284212563968/gastro-sandra-bedienungsanleitung-medion, https://hevaxadoher.tumblr.com/post/691895287443243008/zircon-multiscanner-pro-sl-bedienungsanleitung-hd, https://qukasuvilera.tumblr.com/post/691895198445404160/fs1130mfp-handbuch, https://jipececimumu.tumblr.com/post/691895344964960256/vas-5903-handbuch-ipad.

A duckweed-covered canal in an elm forest in Dublin, Ireland, shows the reflection of three of many elms (Ulmus minor), that died from a fungus that was introduced from Asia into Europe and America more than a century ago, and to which the elms are slowly developing resistance.

found @putin-on-the-ritz

Dutch Elm Disease

Why is the ailment afflicting elm trees called “Dutch Elm Disease?” Well according to BioForest Technologies Inc. “a young phytopathologist from the Netherlands named Bea Schwartz first isolated a fungus from dying elms in 1921, which would give rise to the Dutch elm disease moniker. Another Dutch researcher, Christine Buisman, would also be instrumental in showing the disease was, in fact,…

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Bellicidia incompta (syn. Bacidia incompta)

Sap groove lichen

This lichen forms a granular or mealy crust of pale gray, green, or fawn in the wonded and sap-tracked areas of elm trees in Eurasia, with smaller populations in Tunisia and North America. Currently, European elm populations are being absolutly desimated by Dutch elm disease--caused another, less friendly fungus, Ophiostoma novo-ulmi. Fewer elms means fewer species that rely on elms for survival, such as B. incompta. In a lot of ways, that’s just how the system of natural selection works, but that doesn’t mean we have to feel nothing about it, or that we shouldn’t investigate what is happening and figure out our part in it, and mitigate the destruction where possible. All those things can exist at once and that’s just what it means to live on this planet. 

images: source | source | source | source

Lovely dead elm tree (if that is what you are), I am leaving you there for now. #ulmusminor #elmtrees #mincio #parcodelmincio #lamacchinafissa #firewood #niceshapes #ruralgardens #readingretreatsinruralitaly #olmocampestre #grafiosi #alberomorto #fungoascomicete #ophiostoma ulmi (presso La Macchina Fissa) https://www.instagram.com/p/CAGPN6cpZD_/?igshid=1m761irfa1x77

===General information=== Dutch elm disease (DED) is a serious disease of elms caused by the fungus Ophiostoma novo-ulmi. It is a type of disease known as a vascular wilt because the fungus blocks the vascular (water transport) system, causing the branches to wilt and die. It is spread by elm bark beetles. Damage is usually seen in summer and early autumn. It only occurs in Ulmus spp. (elms) and Zelkova. The symptoms are as follows: At any time in the summer months, all or part of the foliage suddenly turns yellow, then wilts, shrivels and dies Peeling off the bark from affected branches will reveal brown streaks in the outer wood, which appear as a broken or continuous brown ring in the outer growth ring if the branch is cut across All attempts to prevent the spread of DED have been long since abandoned, except in specific areas such as the Isle of Man and Brighton and Hove. However, dead trees are a safety hazard and should be felled promptly. Native elms should not be planted, as they will almost inevitably succumb to DED. Zelkova spp. appear less badly damaged. Resistant hybrid elms have appeared on the market in recent years, but gardeners should note that whilst these are attractive trees, they usually have a different growth habit to those that have been lost and do not exactly replace them. Chemical control No chemical control is feasible. Protectant fungicides were injected into trunks in the early stages of the outbreak, but this was required annually and soon abandoned as impractical. It is also completely impractical to control the beetle vectors. The disease is known as ‘Dutch’ because important early research on it was carried out in the Netherlands. It is caused by the fungus Ophiostoma novo-ulmi which was accidentally introduced to the UK from the USA in the late 1960s on imported elm logs. Prior to this, northern Europe already had a form of DED caused by another related fungus, Ophiostoma ulmi, and for some time it was not realised that the fungus in the UK was different. O. novo-ulmi is not native to the USA and its true origin is unknown. The fungus is spread by elm bark beetles, particularly Scolytus scolytus. Beetles breed in dead and dying elms, including those killed by the disease, where the larvae tunnel in the bark and outermost wood, forming galleries. The fungus produces sticky spores in these galleries, which contaminate the newly hatched adult beetles as they emerge. They then fly to healthy elms, where they feed on young bark and introduce the pathogen into the conducting tissue (xylem) of the tree. The fungus grows in the xylem, blocking water flow and causing rapid wilting and death. It can spread rapidly down rows of hedgerow elms through root grafts formed between adjacent trees. The beetles tend to attack mature trees over 20-years-old, and therefore the first wave of the disease in the early 1970s was followed by a lull while the trees regenerated from suckers. But these regenerated trees have in turn succumbed. The disease has not quite reached the northern limits of elms and some remain in Scotland. ===*Useful websites=== https://ift.tt/2mnjK27 https://ift.tt/2kQWknV https://ift.tt/1WHq3b6 *Information sourced from the above websites

The growth of aggressive and non-aggressive strains of Ophiostoma ulmi in susceptible and resistant Elms, a sc

http://dlvr.it/PZPr5C

Compost DED Education

The City of Saskatoon is acting on the instances of Dutch Elm Disease found in the city! An informational pamphlet about Dutch Elm Disease DED will be given to those who arrive at the compost depot with elm over the summer 2021 months! The pamphlet will illustrate the dangers to the city urban forest if elm is disposed of incorrectly, and why the guidelines are in place to prevent a pandemic from…

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===General information=== Dutch elm disease (DED) is a serious disease of elms caused by the fungus Ophiostoma novo-ulmi. It is a type of disease known as a vascular wilt because the fungus blocks the vascular (water transport) system, causing the branches to wilt and die. It is spread by elm bark beetles. Damage is usually seen in summer and early autumn. It only occurs in Ulmus spp. (elms) and Zelkova. The symptoms are as follows: At any time in the summer months, all or part of the foliage suddenly turns yellow, then wilts, shrivels and dies Peeling off the bark from affected branches will reveal brown streaks in the outer wood, which appear as a broken or continuous brown ring in the outer growth ring if the branch is cut across All attempts to prevent the spread of DED have been long since abandoned, except in specific areas such as the Isle of Man and Brighton and Hove. However, dead trees are a safety hazard and should be felled promptly. Native elms should not be planted, as they will almost inevitably succumb to DED. Zelkova spp. appear less badly damaged. Resistant hybrid elms have appeared on the market in recent years, but gardeners should note that whilst these are attractive trees, they usually have a different growth habit to those that have been lost and do not exactly replace them. Chemical control No chemical control is feasible. Protectant fungicides were injected into trunks in the early stages of the outbreak, but this was required annually and soon abandoned as impractical. It is also completely impractical to control the beetle vectors. The disease is known as ‘Dutch’ because important early research on it was carried out in the Netherlands. It is caused by the fungus Ophiostoma novo-ulmi which was accidentally introduced to the UK from the USA in the late 1960s on imported elm logs. Prior to this, northern Europe already had a form of DED caused by another related fungus, Ophiostoma ulmi, and for some time it was not realised that the fungus in the UK was different. O. novo-ulmi is not native to the USA and its true origin is unknown. The fungus is spread by elm bark beetles, particularly Scolytus scolytus. Beetles breed in dead and dying elms, including those killed by the disease, where the larvae tunnel in the bark and outermost wood, forming galleries. The fungus produces sticky spores in these galleries, which contaminate the newly hatched adult beetles as they emerge. They then fly to healthy elms, where they feed on young bark and introduce the pathogen into the conducting tissue (xylem) of the tree. The fungus grows in the xylem, blocking water flow and causing rapid wilting and death. It can spread rapidly down rows of hedgerow elms through root grafts formed between adjacent trees. The beetles tend to attack mature trees over 20-years-old, and therefore the first wave of the disease in the early 1970s was followed by a lull while the trees regenerated from suckers. But these regenerated trees have in turn succumbed. The disease has not quite reached the northern limits of elms and some remain in Scotland. ===*Useful websites=== https://ift.tt/2mnjK27 https://ift.tt/2kQWknV https://ift.tt/1WHq3b6 *Information sourced from the above websites

===General information=== Dutch elm disease (DED) is a serious disease of elms caused by the fungus Ophiostoma novo-ulmi. It is a type of disease known as a vascular wilt because the fungus blocks the vascular (water transport) system, causing the branches to wilt and die. It is spread by elm bark beetles. Damage is usually seen in summer and early autumn. It only occurs in Ulmus spp. (elms) and Zelkova. The symptoms are as follows: At any time in the summer months, all or part of the foliage suddenly turns yellow, then wilts, shrivels and dies Peeling off the bark from affected branches will reveal brown streaks in the outer wood, which appear as a broken or continuous brown ring in the outer growth ring if the branch is cut across All attempts to prevent the spread of DED have been long since abandoned, except in specific areas such as the Isle of Man and Brighton and Hove. However, dead trees are a safety hazard and should be felled promptly. Native elms should not be planted, as they will almost inevitably succumb to DED. Zelkova spp. appear less badly damaged. Resistant hybrid elms have appeared on the market in recent years, but gardeners should note that whilst these are attractive trees, they usually have a different growth habit to those that have been lost and do not exactly replace them. Chemical control No chemical control is feasible. Protectant fungicides were injected into trunks in the early stages of the outbreak, but this was required annually and soon abandoned as impractical. It is also completely impractical to control the beetle vectors. The disease is known as ‘Dutch’ because important early research on it was carried out in the Netherlands. It is caused by the fungus Ophiostoma novo-ulmi which was accidentally introduced to the UK from the USA in the late 1960s on imported elm logs. Prior to this, northern Europe already had a form of DED caused by another related fungus, Ophiostoma ulmi, and for some time it was not realised that the fungus in the UK was different. O. novo-ulmi is not native to the USA and its true origin is unknown. The fungus is spread by elm bark beetles, particularly Scolytus scolytus. Beetles breed in dead and dying elms, including those killed by the disease, where the larvae tunnel in the bark and outermost wood, forming galleries. The fungus produces sticky spores in these galleries, which contaminate the newly hatched adult beetles as they emerge. They then fly to healthy elms, where they feed on young bark and introduce the pathogen into the conducting tissue (xylem) of the tree. The fungus grows in the xylem, blocking water flow and causing rapid wilting and death. It can spread rapidly down rows of hedgerow elms through root grafts formed between adjacent trees. The beetles tend to attack mature trees over 20-years-old, and therefore the first wave of the disease in the early 1970s was followed by a lull while the trees regenerated from suckers. But these regenerated trees have in turn succumbed. The disease has not quite reached the northern limits of elms and some remain in Scotland. ===*Useful websites=== https://ift.tt/2mnjK27 https://ift.tt/2kQWknV https://ift.tt/1WHq3b6 *Information sourced from the above websites

===General information=== Dutch elm disease (DED) is a serious disease of elms caused by the fungus Ophiostoma novo-ulmi. It is a type of disease known as a vascular wilt because the fungus blocks the vascular (water transport) system, causing the branches to wilt and die. It is spread by elm bark beetles. Damage is usually seen in summer and early autumn. It only occurs in Ulmus spp. (elms) and Zelkova. The symptoms are as follows: At any time in the summer months, all or part of the foliage suddenly turns yellow, then wilts, shrivels and dies Peeling off the bark from affected branches will reveal brown streaks in the outer wood, which appear as a broken or continuous brown ring in the outer growth ring if the branch is cut across All attempts to prevent the spread of DED have been long since abandoned, except in specific areas such as the Isle of Man and Brighton and Hove. However, dead trees are a safety hazard and should be felled promptly. Native elms should not be planted, as they will almost inevitably succumb to DED. Zelkova spp. appear less badly damaged. Resistant hybrid elms have appeared on the market in recent years, but gardeners should note that whilst these are attractive trees, they usually have a different growth habit to those that have been lost and do not exactly replace them. Chemical control No chemical control is feasible. Protectant fungicides were injected into trunks in the early stages of the outbreak, but this was required annually and soon abandoned as impractical. It is also completely impractical to control the beetle vectors. The disease is known as ‘Dutch’ because important early research on it was carried out in the Netherlands. It is caused by the fungus Ophiostoma novo-ulmi which was accidentally introduced to the UK from the USA in the late 1960s on imported elm logs. Prior to this, northern Europe already had a form of DED caused by another related fungus, Ophiostoma ulmi, and for some time it was not realised that the fungus in the UK was different. O. novo-ulmi is not native to the USA and its true origin is unknown. The fungus is spread by elm bark beetles, particularly Scolytus scolytus. Beetles breed in dead and dying elms, including those killed by the disease, where the larvae tunnel in the bark and outermost wood, forming galleries. The fungus produces sticky spores in these galleries, which contaminate the newly hatched adult beetles as they emerge. They then fly to healthy elms, where they feed on young bark and introduce the pathogen into the conducting tissue (xylem) of the tree. The fungus grows in the xylem, blocking water flow and causing rapid wilting and death. It can spread rapidly down rows of hedgerow elms through root grafts formed between adjacent trees. The beetles tend to attack mature trees over 20-years-old, and therefore the first wave of the disease in the early 1970s was followed by a lull while the trees regenerated from suckers. But these regenerated trees have in turn succumbed. The disease has not quite reached the northern limits of elms and some remain in Scotland. ===*Useful websites=== https://ift.tt/2mnjK27 https://ift.tt/2kQWknV https://ift.tt/1WHq3b6 *Information sourced from the above websites

===General information=== Dutch elm disease (DED) is a serious disease of elms caused by the fungus Ophiostoma novo-ulmi. It is a type of disease known as a vascular wilt because the fungus blocks the vascular (water transport) system, causing the branches to wilt and die. It is spread by elm bark beetles. Damage is usually seen in summer and early autumn. It only occurs in Ulmus spp. (elms) and Zelkova. The symptoms are as follows: At any time in the summer months, all or part of the foliage suddenly turns yellow, then wilts, shrivels and dies Peeling off the bark from affected branches will reveal brown streaks in the outer wood, which appear as a broken or continuous brown ring in the outer growth ring if the branch is cut across All attempts to prevent the spread of DED have been long since abandoned, except in specific areas such as the Isle of Man and Brighton and Hove. However, dead trees are a safety hazard and should be felled promptly. Native elms should not be planted, as they will almost inevitably succumb to DED. Zelkova spp. appear less badly damaged. Resistant hybrid elms have appeared on the market in recent years, but gardeners should note that whilst these are attractive trees, they usually have a different growth habit to those that have been lost and do not exactly replace them. Chemical control No chemical control is feasible. Protectant fungicides were injected into trunks in the early stages of the outbreak, but this was required annually and soon abandoned as impractical. It is also completely impractical to control the beetle vectors. The disease is known as ‘Dutch’ because important early research on it was carried out in the Netherlands. It is caused by the fungus Ophiostoma novo-ulmi which was accidentally introduced to the UK from the USA in the late 1960s on imported elm logs. Prior to this, northern Europe already had a form of DED caused by another related fungus, Ophiostoma ulmi, and for some time it was not realised that the fungus in the UK was different. O. novo-ulmi is not native to the USA and its true origin is unknown. The fungus is spread by elm bark beetles, particularly Scolytus scolytus. Beetles breed in dead and dying elms, including those killed by the disease, where the larvae tunnel in the bark and outermost wood, forming galleries. The fungus produces sticky spores in these galleries, which contaminate the newly hatched adult beetles as they emerge. They then fly to healthy elms, where they feed on young bark and introduce the pathogen into the conducting tissue (xylem) of the tree. The fungus grows in the xylem, blocking water flow and causing rapid wilting and death. It can spread rapidly down rows of hedgerow elms through root grafts formed between adjacent trees. The beetles tend to attack mature trees over 20-years-old, and therefore the first wave of the disease in the early 1970s was followed by a lull while the trees regenerated from suckers. But these regenerated trees have in turn succumbed. The disease has not quite reached the northern limits of elms and some remain in Scotland. ===*Useful websites=== https://ift.tt/2mnjK27 https://ift.tt/2kQWknV https://ift.tt/1WHq3b6 *Information sourced from the above websites

===General information=== Dutch elm disease (DED) is a serious disease of elms caused by the fungus Ophiostoma novo-ulmi. It is a type of disease known as a vascular wilt because the fungus blocks the vascular (water transport) system, causing the branches to wilt and die. It is spread by elm bark beetles. Damage is usually seen in summer and early autumn. It only occurs in Ulmus spp. (elms) and Zelkova. The symptoms are as follows: At any time in the summer months, all or part of the foliage suddenly turns yellow, then wilts, shrivels and dies Peeling off the bark from affected branches will reveal brown streaks in the outer wood, which appear as a broken or continuous brown ring in the outer growth ring if the branch is cut across All attempts to prevent the spread of DED have been long since abandoned, except in specific areas such as the Isle of Man and Brighton and Hove. However, dead trees are a safety hazard and should be felled promptly. Native elms should not be planted, as they will almost inevitably succumb to DED. Zelkova spp. appear less badly damaged. Resistant hybrid elms have appeared on the market in recent years, but gardeners should note that whilst these are attractive trees, they usually have a different growth habit to those that have been lost and do not exactly replace them. Chemical control No chemical control is feasible. Protectant fungicides were injected into trunks in the early stages of the outbreak, but this was required annually and soon abandoned as impractical. It is also completely impractical to control the beetle vectors. The disease is known as ‘Dutch’ because important early research on it was carried out in the Netherlands. It is caused by the fungus Ophiostoma novo-ulmi which was accidentally introduced to the UK from the USA in the late 1960s on imported elm logs. Prior to this, northern Europe already had a form of DED caused by another related fungus, Ophiostoma ulmi, and for some time it was not realised that the fungus in the UK was different. O. novo-ulmi is not native to the USA and its true origin is unknown. The fungus is spread by elm bark beetles, particularly Scolytus scolytus. Beetles breed in dead and dying elms, including those killed by the disease, where the larvae tunnel in the bark and outermost wood, forming galleries. The fungus produces sticky spores in these galleries, which contaminate the newly hatched adult beetles as they emerge. They then fly to healthy elms, where they feed on young bark and introduce the pathogen into the conducting tissue (xylem) of the tree. The fungus grows in the xylem, blocking water flow and causing rapid wilting and death. It can spread rapidly down rows of hedgerow elms through root grafts formed between adjacent trees. The beetles tend to attack mature trees over 20-years-old, and therefore the first wave of the disease in the early 1970s was followed by a lull while the trees regenerated from suckers. But these regenerated trees have in turn succumbed. The disease has not quite reached the northern limits of elms and some remain in Scotland. ===*Useful websites=== https://ift.tt/2mnjK27 https://ift.tt/2kQWknV https://ift.tt/1WHq3b6 *Information sourced from the above websites

===General information=== Dutch elm disease (DED) is a serious disease of elms caused by the fungus Ophiostoma novo-ulmi. It is a type of disease known as a vascular wilt because the fungus blocks the vascular (water transport) system, causing the branches to wilt and die. It is spread by elm bark beetles. Damage is usually seen in summer and early autumn. It only occurs in Ulmus spp. (elms) and Zelkova. The symptoms are as follows: At any time in the summer months, all or part of the foliage suddenly turns yellow, then wilts, shrivels and dies Peeling off the bark from affected branches will reveal brown streaks in the outer wood, which appear as a broken or continuous brown ring in the outer growth ring if the branch is cut across All attempts to prevent the spread of DED have been long since abandoned, except in specific areas such as the Isle of Man and Brighton and Hove. However, dead trees are a safety hazard and should be felled promptly. Native elms should not be planted, as they will almost inevitably succumb to DED. Zelkova spp. appear less badly damaged. Resistant hybrid elms have appeared on the market in recent years, but gardeners should note that whilst these are attractive trees, they usually have a different growth habit to those that have been lost and do not exactly replace them. Chemical control No chemical control is feasible. Protectant fungicides were injected into trunks in the early stages of the outbreak, but this was required annually and soon abandoned as impractical. It is also completely impractical to control the beetle vectors. The disease is known as ‘Dutch’ because important early research on it was carried out in the Netherlands. It is caused by the fungus Ophiostoma novo-ulmi which was accidentally introduced to the UK from the USA in the late 1960s on imported elm logs. Prior to this, northern Europe already had a form of DED caused by another related fungus, Ophiostoma ulmi, and for some time it was not realised that the fungus in the UK was different. O. novo-ulmi is not native to the USA and its true origin is unknown. The fungus is spread by elm bark beetles, particularly Scolytus scolytus. Beetles breed in dead and dying elms, including those killed by the disease, where the larvae tunnel in the bark and outermost wood, forming galleries. The fungus produces sticky spores in these galleries, which contaminate the newly hatched adult beetles as they emerge. They then fly to healthy elms, where they feed on young bark and introduce the pathogen into the conducting tissue (xylem) of the tree. The fungus grows in the xylem, blocking water flow and causing rapid wilting and death. It can spread rapidly down rows of hedgerow elms through root grafts formed between adjacent trees. The beetles tend to attack mature trees over 20-years-old, and therefore the first wave of the disease in the early 1970s was followed by a lull while the trees regenerated from suckers. But these regenerated trees have in turn succumbed. The disease has not quite reached the northern limits of elms and some remain in Scotland. ===*Useful websites=== https://ift.tt/2mnjK27 https://ift.tt/2kQWknV https://ift.tt/1WHq3b6 *Information sourced from the above websites

===General information=== Dutch elm disease (DED) is a serious disease of elms caused by the fungus Ophiostoma novo-ulmi. It is a type of disease known as a vascular wilt because the fungus blocks the vascular (water transport) system, causing the branches to wilt and die. It is spread by elm bark beetles. Damage is usually seen in summer and early autumn. It only occurs in Ulmus spp. (elms) and Zelkova. The symptoms are as follows: At any time in the summer months, all or part of the foliage suddenly turns yellow, then wilts, shrivels and dies Peeling off the bark from affected branches will reveal brown streaks in the outer wood, which appear as a broken or continuous brown ring in the outer growth ring if the branch is cut across All attempts to prevent the spread of DED have been long since abandoned, except in specific areas such as the Isle of Man and Brighton and Hove. However, dead trees are a safety hazard and should be felled promptly. Native elms should not be planted, as they will almost inevitably succumb to DED. Zelkova spp. appear less badly damaged. Resistant hybrid elms have appeared on the market in recent years, but gardeners should note that whilst these are attractive trees, they usually have a different growth habit to those that have been lost and do not exactly replace them. Chemical control No chemical control is feasible. Protectant fungicides were injected into trunks in the early stages of the outbreak, but this was required annually and soon abandoned as impractical. It is also completely impractical to control the beetle vectors. The disease is known as ‘Dutch’ because important early research on it was carried out in the Netherlands. It is caused by the fungus Ophiostoma novo-ulmi which was accidentally introduced to the UK from the USA in the late 1960s on imported elm logs. Prior to this, northern Europe already had a form of DED caused by another related fungus, Ophiostoma ulmi, and for some time it was not realised that the fungus in the UK was different. O. novo-ulmi is not native to the USA and its true origin is unknown. The fungus is spread by elm bark beetles, particularly Scolytus scolytus. Beetles breed in dead and dying elms, including those killed by the disease, where the larvae tunnel in the bark and outermost wood, forming galleries. The fungus produces sticky spores in these galleries, which contaminate the newly hatched adult beetles as they emerge. They then fly to healthy elms, where they feed on young bark and introduce the pathogen into the conducting tissue (xylem) of the tree. The fungus grows in the xylem, blocking water flow and causing rapid wilting and death. It can spread rapidly down rows of hedgerow elms through root grafts formed between adjacent trees. The beetles tend to attack mature trees over 20-years-old, and therefore the first wave of the disease in the early 1970s was followed by a lull while the trees regenerated from suckers. But these regenerated trees have in turn succumbed. The disease has not quite reached the northern limits of elms and some remain in Scotland. ===*Useful websites=== https://ift.tt/2mnjK27 https://ift.tt/2kQWknV https://ift.tt/1WHq3b6 *Information sourced from the above websites