2003 Annual and Perennial Trial Results

August 2005 Plant of the Month Malus Louisa Louisa crabapple tree zone: by Jim Stolzenburg, Bailey Nurseries Inc.

Crabapples are a staple in the upper Midwest landscape. They're hardy, have at least one season (albeit relatively short) of a high quality show, and generally are adequate to good performers in the ornamental palette of plants we can utilize.

But there are crabapples that can and do perform much better than just 'adequately.' And we should expect more from our crabapples. Many of our older crabapples no longer fit today's lifestyles or landscapes. Their statures are too large for today's urban gardening spaces, their wild branching habits need too much maintenance, their large fruit displays become lawn messes, their foliage much more susceptible to changing disease pressures. We should be refusing to grow these crabapples and educate our customers to utilize better cultivars.

Once such cultivar is 'Louisa' crabapple. After many years of observing this ornamental and reading evaluations from across the country, it has risen to the top of my list of crabs and even of small ornamental trees. If we can get past the idea that the only worth a crabapple has is its spring flower display, then this tree surely has all season appeal. First of all it is a weeping type which sets it apart of most other crabs. And unlike many of its cousins, it does not throw errant watersprouts, although its branching habit is unorthodox to be sure. Generally the trunk is trained straight up to about 4-5 feet and after that is allowed to weep or grow somewhat horizontally. It does this with a kind of wavy habit, and then towards the outward part of the branch will weep to the ground. In flower and foliage, it is very attractive, but it really stands out in the winter landscape where the architecture can be viewed against the snow covered landscape. Birds love to nest in this labyrinth of branches. Every five years or so, some thinning of lower branches underneath the canopy may be required, but they are easy to reach. In 15 years, Louisa should reach no more than 8-9 feet in height and 10-12 feet in diameter, making it an excellent ornamental for any situation that requires low clearance.

Louisa's red buds open to single, bright, true pink flowers blooming about the same time as the common yellow daffodils. It is a refreshing contrast to the rosy bloom pinks so many of the crabapples have, and shows up best when set against a backdrop of evergreens. As with many other crabs, the flower display can last for maybe 10 days under optimal (cool, calm) conditions or as little as three days when hot and windy. It always gives a good display tending to be slightly biennial, some years a bit better than others. The 3/8-inch fruit begins to color yellow in late August to September and then takes on a reddish blush as it matures. By mid November to December 1st, the fruit is enthusiastically taken by the birds so there is no fruit litter. Unfortunately this also means there is no winter fruit display. Fortunately the winter branching display makes up for it!

In all the testing sites throughout United States conducted by the International Ornamental Crabapple Society, Louisa consistently rates at the top for resistance to the four major diseases of crabapples: apple scab, fireblight, cedar apple rust, frog-eye leaf spot. It is never a detriment in the landscape; its pleasing medium green foliage always looks good right until frost. Louisa truly is a small ornamental crabapple that can be enjoyed all year long.

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