Hi Mel, sorry to hear that. In addition, honey produced in the spring during the rhododendron flowering season is mostly consumed by the bees and is rarely harvested. The first time it happened we suspected pesticide poisoning. When bees collect nectar exclusively from the flowers of these plants then the nectar may have high concentrations of these toxins. Even though it likes … If we do have R.ponticum near us, the research carried out by Professor Stout and Dr  Tiedeken suggests that our honey bees will probably avoid it; additionally the plants are likely to be less toxic than in their native range. I heard that some people have started to raise their bees on Cannabis flowers. Sorry, your blog cannot share posts by email. Rhododendron ponticum is an invasive species and this study demonstrated that rhododendron toxins are poisonous to honeybees and mining bees. These apparently affect native and honeybees but not bumblebees. It can poison many species, from humans to horses, birds and insects that ingest it. It contains an andromedotoxin. I think the main evolutionary advantage of the graynotoxins is that they are poisonous to grazing animals like horses, which helps prevent the plants from being eaten. Our hives sit on the ground with a strip of coreflex about 25 cm wide in front that keeps the grass from the entrance but also works as a perfect examining platform. Spectacular and beautiful, not many people know the common rhododendron hides a poisonous secret – its nectar is toxic to bees. ( Log Out /  Some species of rhododendron are poisonous to grazing animals because of a toxin called grayanotoxin in their pollen and nectar. Now & then one encounters the folklorishly exaggerated "warning" that rhododendron flowers are so poisonous that bees manufacture toxic honey from them. Common rhododendron is regarded as an unwelcome alien invader and being eradicated from Nature Reserves here in North Wales, so not a good hunting ground for ‘mad honey’ here! The toxic component of rhododendrons and azaleas can be found in very high concentrations in honey made by bees that feed on them. People have been known to become ill from eating honey made by bees feeding on rhododendron and azalea flowers. You are such a talented and interesting writer. For that reason, it can't be controlled by grazing, as is often the case with other aggressive shrubs. They also tested the grayanotoxins on an Irish species of mining bee, Andrena scotica; this species did not suffer increased mortality but had its behaviour severely affected, for example becoming paralysed or spending increased time grooming. That is so perplexing and must be very upsetting to see . I found a list of other plants at http://www.buzzaboutbees.net/Plants-Toxic-for-Bees.html – scroll down to the blue ‘List Of Plants Toxic For Bees’ chart – perhaps you could check whether any of these grow near you. - 3 ft. 0 in. Summer Titi – Cyrilla racemiflora – is toxic to honey bees and can cause the condition called “purple brood”. The best poisonous plants for honey bees are the plants in the family Ericaceae, particularly rhododendrons, which produce a lot of nectar and pollen. You can feel confident your PJM is not poisoning bees. Here’s why…. Being sterile, it does not produce seed. Bees seem to build up well when foraging on R. ponticum nectar and pollen, but the author, who is a beekeeper on Colonsay, reports that every spring some of his bees show symptoms of poisoning. (How do you find the time!?). Insects, Diseases, and Other Plant Problems: Rhododendrons are susceptible to insect and disease problems. ( Log Out /  In the foyer of the school where the event takes place there are people who have products and plants to sell specifically of interest to beekeepers. I hope this helps.”, So it sounds hopeful that the trees would not be a problem for you. And ultimately, we may also have a … I was very mad at him too. Not all plants are safe for all pollinators. I’ve also, more than once, found bees landing in the grass about 50 cm in front of hives affected this way as if bees are having troubles finding home. It may come as a surprise that many plant materials are poisonous or toxic to honey bees.. Jen, PJM Rhododendron is a sterile hybrid cultivar created by crossing R. carolinianum and dauricum var. The deaths start slowly (tens, not hundreds), build in number of deaths and colonies affected, go away, come back and the whole drama takes about a month to finish doing its damage. Stories tell of soldiers finding rhododendron honey left by fleeing citizens. Lindy mentions above that Aesculus Californica (Calfornian Chestnut) trees are known to be poisonous to bees. Rhododendron ponticum is known as a source of toxic nectar which causes bees to produce ‘mad honey’, used by European armies through the ages as a weapon of war. My beekeeping buddy Emma (Mrs Apis Mellifera) sent me a useful link from the Poison Garden website which suggests that most of us will be unable to tell what is R.ponticum and what is a hybrid – and therefore potentially less toxic – plant. My home is surrounded by 8 acres of rhododendrons. The toxicity found in varieties of rhododendron is not uniform across all the plants' species, although it is a characteristic of Rhododendron ponticum, one of the most popular varieties of the shrub. Very interesting! Morphine Change ). The honey thus collected by the Gurung owes its inebriating properties to the nectar which the giant bees gather from a deep red-flowered species of Rhododendron, which, in turn, owes its toxicity to the compound grayanotoxin, widespread in the plant family Ericaceae, to which the genus Rhododendron belongs. The Poisonous Plant Guide is constructed to enable location of a plant by either knowing the common or botanical name of the plant. The grayanotoxin is the plant’s defence against herbivore attack. I’ve asked lots of beekeepers and have been told vaguely that there are plants that kill bees but no one has any specifics (nor can I find them anywhere). It is also common to relatives of rhododendron, such as other members of the azalea, or Ericacae, family. However, the bees know which is which, so you don’t need to worry about poisoning them. Instead, the rhododendron nurtures bumblebees that depend on its flowers, creating a stronger symbiosis. I always thought they were a positive given how early they bloom. A landscape scale chemical analysis comparing R.ponticum plants in Ireland with R.ponticum plants in the species’ native range of Spain and Portugal found that toxin levels were lower overall within the Irish plants. Effects. Botanists from Trinity College Dublin's School of Natural Sciences have discovered that the nectar from a common, non-native plant, is toxic to some Irish bees. Rhododendron Poisonous To Bees A. J. M., Berlin Heights, Ohio, writes: - "Two or three years ago I had some Rhododendrons which came out before the red clover, and would you think it, it was something new for Ohio humble bees . Best to avoid: Rhododendron. Although the toxin can kill the bees, it is well diluted with water in the nectar. Botanists from Trinity College Dublin's School of Natural Sciences have discovered that the nectar from a common, non-native plant, is toxic to some Irish bees. Bumblebees seem to be immune to the toxins. Members of the genus Rhododendron support the following specialized bee: Andrena (Andrena) cornelli. Rhododendron from the heath family (Ericaceae) is poisonous to bees and humans. A bee-friendly garden is a great way to support the population of these pollinators, which is dangerously declining.Did you know that not all flowers are good for bees though? Leaves and flower nectar (including honey made from plant nectar) are sources of the toxin. I feel bad about throwing these, otherwise healthy, trees in the bin but all my friends are bee keepers too so they won’t appreciate such a ‘present’. His nursery is too far away for me to take them back and he didn’t want to drive half way either… Attracting bees, wild birds, insects and other pollinators to the garden seems to be a priority for gardeners these days, but it can be complicated. The rhododendron family of plants includes more than 700 species, but only a handful contain grayanotoxins: Rhododendron ponticum and Rhododendron luteum.Both are common in the rugged areas around the Black Sea. Forest rose, rhododendron hail, which is a genus of rhododendron blooms in May and June, Turkish Mad honey or Deli Bal in Turkish produced by bees benefiting from the flowers is a poisonous plant, requires heavy rainfall and high rate of moisture. In Turkey, not only do the poisonous rhododendrons abound, but the humid, mountainous slopes around the Black Sea provide the perfect habitat for these flowers to grow in monocrop-like swaths. This species yields honey in California but is suspected of poisoning or causing paralysis in bees. A bee-friendly garden is a great way to support the population of these pollinators, which is dangerously declining.Did you know that not all flowers are good for bees though? Not all rhododendron honey is toxic, as not all rhododendrons contain toxic compounds. The goal might be wax, pollen, bee poison production or colony raising (nukes, package bees etc.). Deer browse this plant. The locals know the effect of the honey so they consumer it in minimal amounts. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. http://en.wikipedia.org/wiki/Rhododendron Some species are poisonous to grazing animals. The honey would be left in the path of invading legions; the soldiers would eat the sweet treat and end up vomiting and dizzy from grayanotoxin, a toxin contained in rhododendron honey. Rhododendron honey is said to be toxic only if very recently produced by the bees, so commercially produced honey is unlikely to produce any effects. The ABC & XYZ of Bee Culture mentions that both the nectar and pollen of rhododendron are poisonous to bees as well as humans. Rhododenrons may only be a problem for beekeepers surrounded by large areas of R.ponticum, which could smother out other plants and reduce the amount of forage available for honey bees. I am now convinced that it is killing them and much as it pains me to, I am going to eraditcate it as I feel that, sadlt, bees need all the help they can get these days ! Azaleas are very close relatives of rhododendrons and can cause the same type of toxicity. Horses and cats, like dogs, are susceptible to the poisonous effects of grayantoxin. To become ill from eating honey made by bees feeding on rhododendron,... & a... http: //www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx? kempercode=c163, https: //commons.wikimedia.org/w/index.php? curid=6644210 only honey bees it! And also on the sub-species of honey bee is perhaps the first “ invasive insect ”! Bloom in the book “ plants and Beekeeping ” by F.N.Howes -- tansy ragwort honey is toxic as! 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