Rose Apples

Imagine an apple that tastes something like bell pepper.

That was the first description I could find for rose apples. I had never heard of these edibles until this morning when a friend told me she was having some problems growing hers in San Francisco. Let’s see what we can find out.

Rose apples (Forest & Kim Starr) CC BY 3.0

Rose apple family
 
Despite the name, rose apples are not in the rose family. Instead, they are a type of myrtle (Myrtaceae), making them cousins to cloves, guava, allspice, and eucalyptus.

Rose apples are native to Southeast Asia and the northern parts of Australia. These plants are tropical and cannot handle freezing temperatures. They thrive in moist heat with full sun. If any of these conditions is missing, trees will not produce fruit. They need to be irrigated in summer and kept on the dry side during periods of cold.

Mature trees tend to have a dense crown with many slender, arching branches that can make the tree wider than it is tall. Large, showy flowers appear in early summer.

The fruit is a slightly pear-shaped berry, with a hint of rose fragrance. The flesh is crisp and watery, with a taste that starts out mildly sweet and then turns to a floral rose or slightly bitter taste, depending on who you ask. These fruits are non-climacteric, which means they must be left on the tree until they are fully ripe before being harvested. Once picked, most varieties of rose apples do not ship or store well.

Like apples, rose apples often do not grow true from seed, although some people have had good luck that way. Very often, the fruit is substandard when started this way. Cuttings and most grafts generally fail, as well, so plants are most often reproduced vegetatively, using air layering.

There are four major types of rose apple, each with different characteristics. In many cases, there is an overlap of names, but it’s nothing to worry about unless you’re a botanist.

Jambos rose apples (JonRichfield) CC BY-SA 3.0

Jambos rose apples
 
Jambos rose apples (Syzgium jambos) feature yellow fruit with two seeds. They are also known as plum roses, wax apples, and pomarrosa. These trees grow 10-45’ tall and look very similar to guavas. Unlike guava fruit, which is filled with tiny seeds, these rose apples contain one or two large seeds. Apparently, when the fruit is ripe, you can shake it and hear the seeds rattle. Lance-shaped evergreen leaves and twigs are hairless (glabrous) and the brown bark is smooth. In temperate regions, these trees are self-fertile.

Java apple (Basile Morin) CC BY-SA 4.0

​Java rose apple
 
Java rose apples (Syzgium samarangense) are also known as wax apples, wax jambu, and Java apples. These trees grow 40’ tall and have grayish-pink bark that flakes off. Leaves can be up to 10” long and 4” wide, and they smell nice when crushed. Java rose apples are bell-shaped and come in many different colors, with pale red being the most common.

Malay rose apple (Justinisaacs) CC BY-SA 3.0

Malay rose apples
 
Malay rose apples (Syzgium malaccense) are also known as mountain apples, Malay apples, pomerac, or simply rose apples. The oblong fruit of these plants is said to be refreshing but bland. Some varieties have pink or white skin, but most Malay rose apples have dark red skin and contain only one seed. Trees can grow 40-60’ tall.

Watery rose apple buds (Vinayaraj) CC BY-SA 3.0

Watery rose apples
 
Watery rose apples (Syzgium aqueum) are also known as water apples, bell fruit, and bush cherries. Water apples are true to their name in that they need lots of water, as in monsoon levels. The yellow fruit of water apples is described as the taste of apple and the texture of watermelon. Unlike other rose apples, this variety stores well. Glossy green leaves are also edible.

Rose apple problems
 
While rose apples have few insect pests, it ends up that they are fruit fly magnets. If you are growing rose apples, you need to harvest the fruit as soon as it is ripe. And discard overripe fruit right away. This will interrupt the lifecycle of the fruit flies, along with several other pests.

On the disease front, myrtle rust (Austropuccinia psidii), also known as guava rust, has all but wiped out the Hawaiian rose apple population. Since rose apples are introduced as ornamentals in many regions, this isn’t necessarily a bad thing. Unless it strikes your tree. Other common diseases and disorders of rose apples include anthracnose, leaf spot, mushroom root rot, root rot, and sooty mold.

All that being said, I think insufficient sunlight and cool temperatures are probably the problems being faced by my friend’s tree. [Sorry, Gaea!]
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If you are growing rose apples, we’d love to hear about it in the comments!