Juneberries are also called saskatoon or serviceberries.

Native Range and Climate

The native range of the western juneberry (Amelanchier alnifolia) extends from western Minnesota to northwestern California and all the way up to central Alaska.  They can also be found in scattered parts of the mountain ranges further south.  The climates they generally reside in are warm continental (Dfb, Dsb), warm mediterranean (Csb), and subarctic (Dfc).  While their range often receives an annual rainfall of less than 20 inches (possibly down to 11 inches), it does not extend too far into the semi-arid climate (BSk) and even makes a point to avoid it.  A. alnifolia does not extend too far into the hot summer humid continental climate as well (Dfa).

Alnifolia is the most commonly available species, but there are many others, most of which are native to the wet and humid eastern half of the United States and southeastern Canada.  Amelanchier arborea, canadensis, laevis, and spicata are commonly found in the north and south, while Amelanchier humilis, interior, stolonifera, sanguinea, and nantucketensis are found primarily in the north.


Flavor

Juneberries have a low acid content and are said to range between insipid to quite good, depending on the variety, but they are always considered to be inferior to more popular culinary berries.  This, of course, could change with the introduction of new varieties.  The flavor is often mentioned by writers, nurseries, and studies to be somewhat like a blueberry, but home-growers almost always disagree.  They generally claim juneberries taste like sweet almonds or a combination of sweet almond and apple, but I have seen a few add blueberry or cherry to the mix.  Considering most varieties come from A. alnifolia, it's possible some of these other species are more or less likely to contain more berry-like flavors.  Additionally, a few have said, or implied, that they become more palatable when cooked.  While juneberries appear to have great potential, the sample size of opinions, at this time, is fairly small, since only a few have developed a great interest in the fruit.

In my limited experience, the flavor was quite mild, and they did not taste like almond, apple, or blueberry.  The seeds did make them somewhat nutty, and the flesh was often berry-like, occasionally reminiscent of sweet cherry.  They were fairly good when dried, but I did not try them cooked.  Rain, at some level, seemed to water down their already light flavor, and those that weren't mostly purple in color had practically none.  I was only able to sample from a few small bushes, and I do not know their exact species, but some of them were seedlings of species native to the east or hybrids between them and alnifolia.


Pests

There are a number of pests that feed on juneberry fruit or leaves, but complaints about them are currently few in number.  Regardless, apple curculio and saskatoon sawfly can cause a fairly significant amount of damage to the fruit, and they may become more common as juneberry cultivation increases.


Disease

Since A. alnifolia is native to a drier climate than most other juneberry species, they tend to be more susceptible to disease.  Based on one year at Edmonton, Alberta and two years at Hudson Bay, Saskatchewan, nearly 100% of the leaves were infected with entomosporium spot.  However, the average percentage of the leaf area affected on the most vulnerable varieties generally resided between 3-7%.^[1] More importantly, based on one year at Hudson Bay and Moonlake, Saskatchewan, nearly 100% of the fruit were also affected.^[1] Severity was implied to be very high at Moonlake, and the damage was likely enough to ruin commercial crops at both locations.

In Alberta, Canada, entomosporium spot began being a problem in 1990, and by 1994, the disease was severe enough to ruin over 80% of the crop at most of their orchards (without the use of fungicides).^[2] These observations were made within their native range near cities that receive an average annual rainfall around 17 to 18 inches – most of which falls during spring and summer.  The region is also further up north, which means daytime lasts for a longer duration during the summer.  This would help dry the leaves quicker and create a less favorable condition for the disease.

I cannot say if the infection will be severe enough to ruin the crop for home-growers with low density alnifolia plantings, since they are likely more forgiving, but based on a small sample size, I have only heard complaints about spotting (and mildew) from those growing western juneberries outside of their native range.  Overall, we can assume A. alnifolia is not suitable in wetter climates without the use of fungicides.  Amelanchier species native to the east may be more desirable, but with the possible exception of "Autumn Brilliance", none are really known for their superior fruit quality, since they are only sold for ornamental purposes.  However, rust can ruin the entire crop of at least some eastern species, especially when planted in a more shaded location.

Juneberries can also suffer from fireblight, but I have only heard of one complaint from home-growers.  Some people, all of whom were located in the east, have even made a point to say that they have never seen blight on their juneberries, including one who has lost apple trees due to the disease, but I am not sure if these home-growers were referring to eastern or western Amelanchier species.


Toxicity

Like many other species in the Rosaceae family, juneberries contain cyanogenic glucosides, such as prunasin and amygdalin, in the leaves, branches, and seeds.  The fruit is the only part that is generally considered to be edible.  These substances convert into hydrogen cyanide in the body, which can be highly toxic in fairly small amounts.  When it comes to juneberries, avoiding the consumption of the seeds is not practical, nor is it considered, implying the amount of cyanogenic glucosides present is small enough to tolerate.  However, it's still nice to know, how much is too much? I have only found one study that made it somewhat clear.

Six plants consisting of 5 different varieties grown in one of three different regions were tested to determine the maximum amount of hydrogen cyanide (HCN) they could produce.  Smoky was the only variety tested at two different locations, and at both locations, it had a much higher potential HCN than most other varieties (4.4 mg/kg in the red stage and 9.4 in the purple stage at Manitoba; 8.19 mg/kg in the red stage and 7.59 in the purple stage at Alberta).  The exception was Theissen, which had a similar amount (8.15 mg/kg in the purple stage – the only stage tested).^[3] Honeywood (4.24 mg/kg while red and 3.08 while purple), Northline (5.94 mg/kg while red and 3.51 while purple), and Martin (slightly above 3 mg/kg in the red, red-purple, and the purple stage) were the other varieties tested.  Most, but not all, had a much lower potential HCN amount in (what I assume to be the late part of) the green stage.^[3]

For comparison, sweet almonds can produce roughly 2x to 10x the amount of hydrogen cyanide (16.2 to 32.4 mg/kg)^[4] as Smoky and Theissen juneberries, although this too is based on a small sample size.  Bitter almonds (918 to 1215 mg/kg) and apricot kernels (540 to 1193.4 mg/kg) can produce significantly more hydrogen cyanide and should be avoided entirely.^[4]

The study mentioned that the World Health Organization's 2004 "accepted cyanide toxicity level" was 1 mg/kg body weight.^[3] Not only do I not see that in their source, but their choice of words severely underplays how dangerous it can be to consume that much hydrogen cyanide.  Their source, however, does imply that the LD50 for humans is around 1.4 mg/kg body weight (bw) and the lowest reported lethal dose was 0.54 mg/kg bw.  In other studies, the acute oral lethal dose of HCN for humans is often cited to be 0.5-3.5 mg/kg bw.^[5]

While using the highest value of potential HCN from the study (9.4 mg/kg) along with the acute oral lethal dose of 0.5 mg/kg bw, and assuming a 100% hydrolysis of the glucosides within the body, a 25kg (56 pound) child should not consume anywhere near 1.33kg (2.9 pounds) worth of juneberries.  This would amount to 3.72kg (8.2 pounds) for a 70kg (154 pound) adult.

Due to the uncertainty of the type of damage chronic intake could cause, various organizations have established a Tolerable Daily Intake (TDI) of cyanide significantly lower than the minimum acute oral lethal dose of 0.5 mg/kg bw.  The Committee on Toxicity states that one should not consume more than 0.042mg/kg bw of cyanide within one hour or 0.083 mg/kg bw per day, while the Counsel of Europe, as well as WHO, established a TDI of 0.02 mg/kg bw or lower.^[6]

Using the TDI of 0.02 mg/kg bw along with the average value for all six results in the purple stage (5.79 mg/kg) as well as the highest potential HCN value from the study (9.4 mg/kg), we get a maximum daily limit of 53.2g (0.117 pounds) to 86.4g (0.19 pounds) for the 25kg (56 pound) child and 149g (0.328 pounds) to 242g (0.533 pounds) for the 70kg (154 pound) adult per day.  For comparison, a 2-1/8" diameter plum is said to be around 66g.