Apple Scab Resistant Crabapple Varieties

News Article

The cool, wet weather this spring has created ideal conditions for the development of apple scab on susceptible crabapple varieties. Scab is caused by the fungus Venturia inaequalis. Initial symptoms are small olive-green to black spots on the foliage. Eventually the leaves turn yellow and fall from the tree. Highly susceptible crabapple varieties may lose most of their foliage by midsummer. The heavy defoliation will weaken the trees somewhat, but will usually not kill them. The damage is mainly aesthetic. Heavily defoliated trees are unattractive.

Apple scab may be prevented by the application of fungicides, such as chlorothalonil, when growth first appears. Repeat at 7 to 10 day intervals until about the middle of June. Sanitation also plays an important role in controlling apple scab. Raking and destroying the leaves as they fall helps control the disease next season. The best way to avoid apple scab problems is to plant scab resistant varieties. The following crabapple varieties perform well in Iowa and also possess good to excellent resistance to apple scab.

Crabapples for Iowa
Species or Variety Flower Color Fruit Color Ht/Wd Tree Form
'Adams' red dark red 20/20 round
'Adirondack' white red 20/10 upright
'Amberina' white orange-red 12/12 upright-oval
'Anne E.' white red 10/10 weeping
'Autumn Glory' white orange-red 15/15 spreading
baccata 'Walters' white yellow-orange 15/15 round
'Bob White' white yellow 20/25 horizontal
'Candied Apple' pink dark red 15/15 weeping
'Centurion' red red 20/15 upright-spreading
'David' white red 15/15 round
'Donald Wyman' white red 20/20 round
'Doubloons' white yellow 12/10 upright-spreading
floribunda pink white yellow 20/25 horizontal
'Golden Raindrops' white yellow 20/15 upright-spreading
'Harvest Gold' white yellow 20/15 upright-spreading
'Indian Magic'* pink orange-red 15/15 round
'Indian Summer' red red 20/20 upright-spreading
'Jewelberry' white red 12/15 spreading
'Louisa' pink yellow 15/15 weeping
'Madonna' white red 20/15 upright-spreading
'Molten Lava' white orange-red 15/15 horizontal
'Pink Satin' pink dark red 15/15 rounded
'Prairifire' red dark red 20/20 upright-spreading
'Professor Sprenger' white orange-red 25/25 round
'Profusion' red dark red 20/20 upright-spreading
'Red Baron' red red 18/10 columnar
'Red Jade' white red 15/15 weeping
'Red Jewel' white red 18/12 upright-oval
'Red Swan' white red 15/15 weeping
sargentii white red 6/12 horizontal
'Sentinel' white red 15/10 upright
'Serenade' white orange 12/12 semi-weeping
'Silver Moon' white dark red 25/15 upright-oval
'Sinai Fire' white orange-red 15/15 weeping
'Snowdrift'* white orange 20/20 round
'Sugar Tyme' white red 20/20 round
'Winter Gold' white yellow 25/20 vase-shaped
x zumi 'Calocarpa' white red 15/20 horizontal
x zumi 'Winter Gem' white red 15/12 upright-spreading
x zumi 'Wooster' white orange-red 12/15 horizontal

* 'Indian Magic' and 'Snowdrift' possess good resistance to apple scab. However, they will lose considerable foliage whenweather conditions are ideal for scab.

Gardeners should avoid 'Almey,' 'Dorothea,' 'Hopa,' 'PinkPerfection,' 'Radiant,' 'Royalty,' and 'Vanguard.' All thesevarieties are highly susceptible to apple scab. 'Spring Snow' isone of the few crabapple varieties that produces little or nofruit. Unfortunately, it is also severely susceptible to applescab.

If a crabapple tree is in your future landscape plans,select a scab resistant variety at your local garden center ornursery.

This article originally appeared in the June 23, 1995 issue, pp. 1995 issue, pp. 92-93.

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